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For Sanding the most important tool is the Sandpaper.

Sandpaper or glasspaper is a form of paper where an abrasive material has been fixed to its surface.

Sandpaper is part of the "coated abrasives" family of abrasive products. It is used to remove small amounts of material from surfaces, either to make them smoother (painting and wood finishing), to remove a layer of material (e.g. old paint), or sometimes to make the surface rougher (e.g. as a preparation to gluing).

History

The first recorded instance of sandpaper was in 13th century China when crushed shells, seeds, and sand were bonded to parchment using natural gum.

Shark skin was also used as a sandpaper. The rough scales of the living fossil Coelacanth are used by the natives of Comoros as sandpaper.[citation needed]

Sandpaper was originally known as glass paper, as it used particles of glass. Glass frit has sharp-edged particles and cuts well, sand grains are smoothed down and did not work as well as glass. Cheap counterfeit sandpaper has long been passed off as true glass paper; Stalker and Parker cautioned against it as far back as the 17th century.

Glass paper was manufactured by John Oakey's company in London by 1833, who had developed new adhesive techniques and processes that could be mass-produced. A process for making sandpaper was patented in the United States on June 14, 1834 by Isaac Fischer, Jr., of Springfield, Vermont.

In 1916, 3M invented a type of sandpaper with a waterproof backing, known as Wetordry. This allowed use with water as a lubricant, and to carry about particles that would otherwise clog the finest grades. Its first application was for automotive paint refinishing.

Sandpaper has occasionally been used as a surface for painting, as by Joan Miró. Sandpaper was even used as a musical instrument, in Leroy Anderson's Sandpaper Ballet.

Boiled and dried, the rough horsetail is used in Japan as a traditional polishing material, finer than sandpaper.

Types of sandpaper

There are countless varieties of sandpaper, with variations in the paper or backing, the material used for the grit, grit size, and the bond.

Backing

In addition to paper, backing for sandpaper includes cloth (cotton, polyester, rayon), PET film, and "fibre" ,or rubber. Cloth backing is used for sandpaper discs and belts, while mylar is used as backing with extremely fine grits. Fibre or vulcanized fibre is a strong backing material consisting of many layers of polymer impregnated paper. The weight of the backing is usually designated by a letter. For paper backings, the weight ratings range from "A" to "F," with A designating the lightest and F the heaviest. Letter nomenclature follows a different system for cloth backings, with the weight of the backing rated J, X, Y , T, and M, from lightest to heaviest. A flexible backing allows sandpaper to follow irregular rounded contours of a given workpiece; relatively inflexible backing is optimal for regular rounded or plane surfaces. Sandpaper backings may be glued to the paper or form a separate support structure for moving sandpaper, such as used in sanding belts and discs. Stronger paper or backing increases the ease of sanding wood, so decent quality sand paper is much better than low cost and low quality sandpaper. The harder the backing material is behind the sandpaper, the faster the sanding, the faster the wear of the paper and the rougher the sanded surface.

Material

Materials used for the abrading particles are:

• flint: no longer commonly used
• garnet: commonly used in woodworking
• emery: commonly used to abrade or polish metal
• aluminium oxide: perhaps most common in widest variety of grits; can be used on metal (i.e. body shops) or wood
• silicon carbide: available in very coarse grits all the way through to microgrits, common in wet applications
• alumina-zirconia: (an aluminium oxide–zirconium oxide alloy), used for machine grinding applications
• chromium oxide: used in extremely fine micron grit (micrometre level) papers
• ceramic aluminum oxide: used in high pressure applications, used in both coated abrasives, as well as in bonded abrasives.

As well, sandpaper may be "stearated" where a dry lubricant is loaded to the abrasive. Stearated papers are useful in sanding coats of finish and paint as the stearate "soap" prevents clogging and increases the useful life of the sandpaper. Aluminium Oxide with stearate is also known as PS33, a Klingspor Abrasives product. The harder the grit material, the easier the sanding of surfaces like wood. The grit material for polishing granite slab has to be harder than granite.

Innovative abrading surfaces now include long-life stainless steel sanding discs.

Bonds

Different adhesives are used to bond the abrasive to the paper. Hide glue is still used, but this paper often cannot withstand the heat generated when machine sanding and is not waterproof. Waterproof or wet/dry sandpapers use a resin bond and a waterproof backing.

Sandpapers can also be open coat, where the particles are separated from each other and the sandpaper is more flexible. This helps prevent clogging of the sandpaper. The wet and dry sandpaper is best used when wet and when using material like acrylic where it leaves a nice smooth feel afterwards.

Shapes

Sandpaper comes in a number of different shapes and sizes.

• sheet: usually 9 by 11 inches, but other sizes may be available
• belt: usually cloth backed, comes in different sizes to fit different belt sanders.
• disk: made to fit different models of disc and random orbit sanders. May be perforated for some models of sanders. Attachment includes Pressure sensitive adhesive (PSA) and "hook-and-loop" (similar to velcro).
• rolls: known as "Shag Rolls" by many contractors

Grit sizes

Grit size refers to the size of the particles of abrading materials embedded in the sandpaper. A number of different standards have been established for grit size. These standards establish not only the average grit size, but also the allowable variation from the average. The two most common are the United States CAMI (Coated Abrasive Manufacturers Institute, now part of the Unified Abrasives Manufacturers' Association) and the European FEPA (Federation of European Producers of Abrasives) "P" grade. The FEPA system is the same as the ISO 6344 standard. Other systems used in sandpaper include the Japan Industrial Standards Committee (JIS), the micron grade (generally used for very fine grits). The "ought" system was used in the past in the United States. Also, cheaper sandpapers sometimes are sold with nomenclature such as "Coarse", "Medium" and "Fine", but it is not clear to what standards these names refer.

Grinding is an abrasive machining process that uses a grinding wheel as the cutting tool.

A wide variety of machines are used for grinding:

• Hand-cranked knife-sharpening stones (grindstones)
• Handheld power tools such as angle grinders and die grinders
• Various kinds of expensive industrial machine tools called grinding machines
• Bench grinders often found in residential garages and basements

Grinding practice is a large and diverse area of manufacturing and toolmaking. It can produce very fine finishes and very accurate dimensions; yet in mass production contexts it can also rough out large volumes of metal quite rapidly. It is usually better suited to the machining of very hard materials than is "regular" machining (that is, cutting larger chips with cutting tools such as tool bits or milling cutters), and until recent decades it was the only practical way to machine such materials as hardened steels. Compared to "regular" machining, it is usually better suited to taking very shallow cuts, such as reducing a shaft's diameter by half a thousand of an inch (thou).(1 thou == 25 um)

Technically, grinding is a subset of cutting, as grinding is a true metalcutting process. Each grain of abrasive functions as a microscopic single-point cutting edge (although of high negative rake angle), and shears a tiny chip that is analogous to what would conventionally be called a "cut" chip (turning, milling, drilling, tapping, etc.). However, among people who work in the machining fields, the term cutting is often understood to refer to the macroscopic cutting operations, and grinding is often mentally categorized as a "separate" process. This is why the terms are usually used in contradistinction in shop-floor practice, even though technically grinding is a subset of cutting.

Similar abrasive cutting processes are lapping and sanding.

Processes

Selecting which of the following grinding operations to be used is determined by the size, shape, features and the desired production rate.

Surface grinding

Surface grinding uses a rotating abrasive wheel to smooth the flat surface of metallic or nonmetallic materials to give them a more refined look or to attain a desired surface for a functional purpose. The tolerances that are normally achieved with grinding are ± 2 × 10−4inches for a grinding a flat material, and ± 3 × 10−4inches for a parallel surface. (in metric units : 5 um for flat material and 8 um for parallel surface).

The surface grinder is composed of an abrasive wheel, a workholding device known as a chuck, either electromagnetic or vacuum, and a reciprocating table.

Typical workpiece materials include cast iron and minor steel. These two materials don't tend to clog the grinding wheel while being processed. Other materials are aluminum, stainless steel, brass and some plastics.

Cylindrical grinding

Cylindrical grinding (also called center-type grinding) is used in the removing the cylindrical surfaces and shoulders of the workpiece. The workpiece is mounted and rotated by a workpiece holder, also known as a grinding dog or center driver. Both the tool and the workpiece are rotated by separate motors and at different speeds. The axes of rotation tool can be adjusted to produce a variety of shapes.

The five types of cylindrical grinding are: outside diameter (OD) grinding, inside diameter (ID) grinding, plunge grinding, creep feed grinding, and centerless grinding.

A cylindrical grinder has a grinding (abrasive) wheel, two centers that hold the workpiece, and a chuck, grinding dog, or other mechanism to drive the machine. Most cylindrical grinding machines include a swivel to allow for the forming of tapered pieces. The wheel and workpiece move parallel to one another in both the radial and longitudinal directions. The abrasive wheel can have many shapes. Standard disk shaped wheels can be used to create a tapered or straight workpiece geometry while formed wheels are used to create a shaped workpiece. The process using a formed wheel creates less vibration than using a regular disk shaped wheel.

Tolerances for cylindrical grinding are held within five ten-thousandths of an inch (+/- 0.0005) (metrical: +/- 13 um) for diameter and one ten-thousandth of an inch(+/- 0.0001) (metrical: 2.5 um) for roundness. Precision work can reach tolerances as high as five hundred-thousandths of an inch (+/- 0.00005) (metrical: 1.3 um) for diameter and one hundred-thousandth of an inch (+/- 0.00001) (metrical: 0.25 um) for roundness. Surface finishes can range from 2 to 125 microinches (metrical: 50 nm to 3 um), with typical finishes ranging from 8-32 microinches. (metrical: 0.2 um to 0.8 um)

Creep-feed grinding

Creep-feed grinding (CFG) was invented in Germany in the late 1950s by Edmund and Gerhard Lang. Unlike normal grinding, which is used primarily to finish surfaces, CFG is used for high rates of material removal, competing with milling and turning as a manufacturing process choice. Depths of cut of up to 6 mm (0.25 inches) are used along with low workpiece speed. Surfaces with a softer-grade resin bond are used to keep workpiece temperature low and an improved surface finish up to 1.6 micrometres Rmax

With CFG it takes 117 sec to remove 1 in.3 of material, whereas precision grinding would take more than 200 sec to do the same. CFG has the disadvantage of a wheel that is constantly degrading, and requires high spindle power, 51 hp (38 kW), and is limited in the length of part it can machine.

To address the problem of wheel sharpness, continuous-dress creep-feed grinding (CDCF) was developed in the 1970s. It dresses the wheel constantly during machining, keeping it in a state of specified sharpness. It takes only 17 sec. to remove 1 in3 of material, a huge gain in productivity. 38 hp (28 kW) spindle power is required, and runs at low to conventional spindle speeds. The limit on part length was erased.

High-efficiency deep grinding (HEDG) uses plated superabrasive wheels, which never need dressing and last longer than other wheels. This reduces capital equipment investment costs. HEDG can be used on long part lengths, and removes material at a rate of 1 in3 in 83 sec. It requires high spindle power and high spindle speeds.

Peel grinding, patented under the name of Quickpoint in 1985 by Erwin Junker Maschinenfabrik, GmbH in Nordrach, Germany, uses a tool with a with superabrasive nose and can machine cylindrical parts.

VIPER (Very Impressive Performance Extreme Removal), 1999, is a process patented by Rolls-Royce and is used in aerospace manufacturing to produce turbine blades. It uses a continuously dressed aluminum oxide grinding wheel running at high speed. CNC-controlled nozzles apply refrigerated grinding fluid during the cut. VIPER is performed on equipment similar to a CNC machining center, and uses special wheels.

Ultra-high speed grinding (UHSG) can run at speeds higher than 40,000 fpm (200 m/sec), taking 41 sec to remove 1 in.3 of material, but is still in the R&D stage. It also requires high spindle power and high spindle speeds.

Others

Form grinding is a specialized type of cylindrical grinding where the grinding wheel has the exact shape of the final product. The grinding wheel does not traverse the workpiece.

Internal grinding is used to grind the internal diameter of the workpiece. Tapered holes can be ground with the use of internal grinders that can swivel on the horizontal.

Centerless grinding is when the workpiece is supported by a blade instead of by centers or chucks. Two wheels are used. The larger one is used to grind the surface of the workpiece and the smaller wheel is used to regulate the axial movement of the workpiece. Types of centerless grinding include through-feed grinding, in-feed/plunge grinding, and internal centerless grinding.

Pre-grinding When a new tool has been built and has been heat-treated, it is pre-ground before welding or hardfacing commences. This usually involves grinding the OD slightly higher than the finish grind OD to ensure the correct finish size.

Electrochemical grinding is a type of grinding in which a positively charged workpiece in a conductive fluid is eroded by a negatively charged grinding wheel. The pieces from the workpiece are dissolved into the conductive fluid.

Grinding wheel

A grinding wheel is an expendable wheel used for various grinding and abrasive machining operations. It is generally made from a matrix of coarse abrasive particles pressed and bonded together to form a solid, circular shape, various profiles and cross sections are available depending on the intended usage for the wheel. Grinding wheels may also be made from a solid steel or aluminium disc with particles bonded to the surface.

Lubrication

The use of fluids in a grinding process is necessary to cool and lubricate the wheel and workpiece as well as remove the chips produced in the grinding process. The most common grinding fluids are water-soluble chemical fluids, water-soluble oils, synthetic oils, and petroleum-based oils. It is imperative that the fluid be applied directly to the cutting area to prevent the fluid being blown away from the piece due to rapid rotation of the wheel.

Work Material	Cutting Fluid	Application
Aluminum	Light duty oil	Flood
Brass	Light duty oil	Flood
Cast Iron	Heavy duty emulsifiable oil, light duty chemical oil, synthetic oil	Flood
Mild Steel	Heavy duty water soluble oil	Flood
Stainless Steel	Heavy duty emulsifiable oil, heavy duty chemical oil, synthetic oil	Flood
Plastics	Water soluble oil, dry, heavy duty emulsifiable oil, dry, light duty chemical oil, synthetic oil	Flood

The workpiece

Workholding methods

The workpiece is manually clamped to a lathe dog, powered by the faceplate, that holds the piece in between two centers and rotates the piece. The piece and the grinding wheel rotate in opposite directions and small bits of the piece are removed as it passes along the grinding wheel. In some instances special drive centers may be used to allow the edges to be ground. The workholding method affects the production time as it changes set up times.

Workpiece materials

Typical workpiece materials include aluminum, brass, plastics, cast iron, mild steel, and stainless steel. Aluminum, brass and plastics can have poor to fair machinability characteristics for cylindrical grinding. Cast Iron and mild steel have very good characteristics for cylindrical grinding. Stainless steel is very difficult to grind due to its toughness and ability to work harden, but can be worked with the right grade of grinding wheels.

Workpiece geometry

The final shape of a workpiece is the mirror image of the grinding wheel, with cylindrical wheels creating cylindrical pieces and formed wheels creating formed pieces. Typical sizes on workpieces range from .75 in. to 20 in. (metric: 18mm to 1 m) and .80 in. to 75 in. in length (metric: 2 cm to 4 m), although pieces between .25 in. and 60 in. in diameter (metric: 6 mm to 1.5 m) and .30 in. and 100 in. in length (metric: 8 mm to 2.5 m) can be ground. Resulting shapes can range from straight cylinders, straight edged conical shapes, or even crankshafts for engines that experience relatively low torque.

Effects on Workpiece Materials

Mechanical properties will change due to stresses put on the part during finishing. High grinding temperatures may cause a thin martensitic layer to form on the part, which will lead to reduced material strength from microcracks.

Physical property changes include the possible loss of magnetic properties on ferromagnetic materials.

Chemical property changes include an increased susceptibility to corrosion because of high surface stress.

For Sanding the most important tool is the Sandpaper.

Sandpaper or glasspaper is a form of paper where an abrasive material has been fixed to its surface.

Sandpaper is part of the "coated abrasives" family of abrasive products. It is used to remove small amounts of material from surfaces, either to make them smoother (painting and wood finishing), to remove a layer of material (e.g. old paint), or sometimes to make the surface rougher (e.g. as a preparation to gluing).

Filling is the process of covering new constructed area with the floor type that is required to maintain the consistency of the whole building. We provide the best materials and have the appropriate tools to complete the job on hand as quickly and accurate as possible.

Wood finishing refers to the process of embellishing and/or protecting the surface of a wooden material. The process starts with surface preparation, either by sanding by hand (typically using a sanding block or power sander), scraping, or planning. Imperfections or nail holes on the surface may be filled using wood putty or pores may be filled using wood filler. Often, the wood's color is changed by staining, bleaching, ammonia fuming and a number of other techniques. Some woods such as pine or cherry do not take stain evenly, resulting in "blotching". To avoid blotching, a barrier coat such as shellac or "wood conditioner" is applied before the stain. Gel stains are also used to avoid blotching.

Once the wood surface is prepared and stained, a number of coats of finish may be applied, often sanding between coats. Commonly used wood finishes include wax, shellac, drying oils (such as linseed oil or tung oil), lacquer, varnish, or paint. Other finishes called "oil finish" or "Danish oil" are actually thin varnishes with a relatively large amount of oil and solvent. Water-based finishes can cause what is called "raising the grain" where surface fuzz emerges and requires sanding down.

Finally the surface may be polished or buffed using steel wool, pumice, rotten stone and other polishing or rubbing compounds depending on the shine desired. Often, a final coat of wax can be applied over the finish to add a slight amount of protection.

French polishing is not polishing as such, but a method of applying many thin coats of shellac using a rubbing pad, yielding a very fine glossy finish.

Special tools used to apply wood finishes include rags, rubbing pads, brushes, and spray guns. The processes involved and the terminology for the materials used are quite different in Britain than the processes and terms used in the USA. For instance, the process of replicating the look and feel of traditional French polished wood is more commonly done in the UK by "pulling over" precatalysed lacquer, within 24 hours of spraying, whereas in the U.S. a "rubbed" finish is more common.

Comparison of different clear finishes

Clear finishes are intended to make wood look good and meet the demands to be placed on the finish. Choosing a clear finish for wood involves trade-offs between appearance, protection, durability, safety, requirements for cleaning, and ease of application. The following table compares the characteristics of different clear finishes. 'Rubbing qualities' indicates the ease with which a finish can be manipulated to deliver the finish desired. Shellac should be considered in two different ways. It is used as a finish and as a way to manipulate the wood's ability to absorb other finishes by thinning it with denatured alcohol. The alcohol evaporates almost immediately to yield a finish that is completely safe but shellac will attach itself to virtually any surface, even glass, and virtually any other finish can be used over it.

	Appearance	Protection	Durability	Safety	Ease of Application	Reversibility	Rubbing Qualities
Wax	Creates shine	Short Term	Needs frequent reapplication	Safe when solvents in paste wax evaporate	easy, needs sanding	Can easily be removed with solvents	Needs to be buffed
Shellac	Some yellow or orange tint, depending on grade used	Fair against water, good on solvents except alcohol	Durable	Safe when solvent evaporates, used as food and pill coating	French polishing difficult technique to master.	Completely reversible using alcohol	Excellent
Nitrocellulose lacquer	Transparent, good gloss	Decent protection	Soft and somewhat durable	Used toxic solvents Good protection is needed, especially if painted	Requires nice equipment. Kick-on products also available	Completely irreversible	Excellent soft finish
Conversion varnish	Transparent, good gloss	Excellent protection against many substances	Hard and durable	Uses toxic solvents, including toluene. Breathing protection is needed	Requires spray equipment. Used in professional shops only	Difficult to reverse	Excellent hard finish
Linseed oil	Yellow warm glow, pops grain1, darkens with age	Very little	Fairly durable, depending on number of coats	Relatively safe, metallic driers are poisonous	Easy, apply with rags and wipe off. Takes relatively long time to dry	Needs sanding out as oil is absorbed	None
Tung oil	Warm glow, pops grain1, lighter than linseed	Very little	Fairly durable, depending on number of coats	Relatively safe, metallic driers are poisonous	Easy, apply with rags and wipe off. Faster to dry than linseed oil	Needs sanding out as oil is absorbed	None
Alkyd varnish	Not as transparent as lacquer, yellowish/orange tint	Good protection	Durable	Relatively safe, uses petroleum based solvents	Brush or spray. Brushing needs good technique to avoid bubbles & streaks	Can be stripped using paint removers	Fair
Polyurethane varnish	Transparent, many coats can look like plastic	Excellent protection against many substances, tough finish	Durable after approx. 30 day curing period	Relatively safe, uses petroleum based solvents	Application requires some level of skill	Can be stripped using paint removers	Bad, coats do not meld leading to white rings if rubbing out cuts through coat
Water-based polyurethane	Transparent	Good protection..newer products (2009) also UV stable	Durable after approx. 10 day curing period	Safer than oil-based, fewer volatile organic compounds (VOCs)	Brush or spray. Fast drying demands care in application techniques	Can be stripped using paint removers	Bad, coats do not meld leading to white rings if rubbing out cuts through coat
Oil-varnish mixes	Similar to oils unless many coats applied, then takes on characteristics of varnishes	Low, but more than pure oil finishes	Fairly durable, depending on number of coats (archaic product, little used with the availability of modern finishes)	Relatively safe, uses petroleum based solvents	Easy, apply with rags and wipe off. Faster to dry than linseed oil	Needs sanding out as oil is absorbed	None unless many coats applied

1 - accentuates visual properties due to differences in wood grain.'

Automated Wood Finishing Applications

Manufacturers who mass produce products implement automated flatline finish systems that run a on a conveyor belt that first begin by being sanded, then dust is removed, and the wood finish is applied via automated spray guns in an enclosed environment or spray cabin. The material then can enter an oven or be sanded again depending on the manufacturer’s setup. The material can also be re-entered into the assembly line to apply another coat of finish or continue in a system that adds successive coats depending on the layout of the production line.

Additionally two very common methods of automating the wood finishing process are: the Hangline approach and the Towline approach.

With the Hangline approach, wood items being painted or finished are hung by carriers or hangers that are attached to a conveyor system that moves the items overhead or above the floor space. The conveyor itself can be ceiling mounted, wall mounted or supported by floor mounts. A simple overhead conveyor system can be designed to move wood products through several wood finishing processes in a continuous loop. Typical wood finishing processes would include sanding, staining, lacquer and sealing. The Hangline approach to automated wood finishing also allows you the option of moving items up to the warmer air space at the ceiling level to speed up drying process.

The Towline approach to automating wood finishing uses mobile carts that are propelled by conveyors that are mounted in or on the floor. This approach is very useful for moving large, awkward shaped wood products that are difficult or impossible to lift or hang overhead, items such as four-legged wood furniture.

The mobile carts used in the Towline approach can be designed with top platens that rotate either manually or automatically. The rotating top platens allow the operator to have easy access to all sides of the wood item throughout the various wood finishing processes such as sanding, painting and sealing.

Crystallization is the (natural or artificial) process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. Crystallization is also a chemical solid-liquid separation technique, in which mass transfer of a solute from the liquid solution to a pure solid crystalline phase occurs.

Process

The crystallization process consists of two major events, nucleation and crystal growth. Nucleation is the step where the solute molecules dispersed in the solvent start to gather into clusters, on the nanometer scale (elevating solute concentration in a small region), that becomes stable under the current operating conditions. These stable clusters constitute the nuclei. However when the clusters are not stable, they redissolve. Therefore, the clusters need to reach a critical size in order to become stable nuclei. Such critical size is dictated by the operating conditions (temperature, supersaturation, etc.). It is at the stage of nucleation that the atoms arrange in a defined and periodic manner that defines the crystal structure — note that "crystal structure" is a special term that refers to the relative arrangement of the atoms, not the macroscopic properties of the crystal (size and shape), although those are a result of the internal crystal structure.

The crystal growth is the subsequent growth of the nuclei that succeed in achieving the critical cluster size. Nucleation and growth continue to occur simultaneously while the supersaturation exists. Supersaturation is the driving force of the crystallization, hence the rate of nucleation and growth is driven by the existing supersaturation in the solution. Depending upon the conditions, either nucleation or growth may be predominant over the other, and as a result, crystals with different sizes and shapes are obtained (control of crystal size and shape constitutes one of the main challenges in industrial manufacturing, such as for pharmaceuticals). Once the supersaturation is exhausted, the solid-liquid system reaches equilibrium and the crystallization is complete, unless the operating conditions are modified from equilibrium so as to supersaturate the solution again.

Many compounds have the ability to crystallize with different crystal structures, a phenomenon called polymorphism. Each polymorph is in fact a different thermodynamic solid state and crystal polymorphs of the same compound exhibit different physical properties, such as dissolution rate, shape (angles between facets and facet growth rates), melting point, etc. For this reason, polymorphism is of major importance in industrial manufacture of crystalline products.

Crystallization in nature

There are many examples of natural process that involve crystallization.

Geological time scale process examples include:

• Natural (mineral) crystal formation (see also gemstone);
• Stalactite/stalagmite, rings formation.

Usual time scale process examples include:

• Snow flakes formation (see also Koch snowflake);
• Honey crystallization (nearly all types of honey crystallize).

Artificial methods

For crystallization (see also recrystallization) to occur from a solution it must be supersaturated. This means that the solution has to contain more solute entities (molecules or ions) dissolved than it would contain under the equilibrium (saturated solution). This can be achieved by various methods, with 1) solution cooling, 2) addition of a second solvent to reduce the solubility of the solute (technique known as antisolvent or drown-out), 3) chemical reaction and 4) change in pH being the most common methods used in industrial practice. Other methods, such as solvent evaporation, can also be used. The spherical crystallization has some advantages (flowability, bioavailability, ...) for the formulation of pharmaceutical drugs (see ref Nocent & al., 2001)

Applications

There are two major groups of applications for the artificial crystallization process: crystal production and purification.

Crystal production

From a material industry perspective:

• Macroscopic crystal production: for supply the demand of natural-like crystals with methods that "accelerate time-scale" for massive production and/or perfection.
  • Ionic crystal production;
  • Covalent crystal production.
• Tiny size crystals:
  • Powder, sand and smaller sizes: using methods for powder and controlled (nanotechnology fruits) forms.
    • Mass-production: on chemical industry, like salt-powder production.
    • Sample production: small production of tiny crystals for material characterization. Controlled recrystallization is an important method to supply unusual crystals, that are needed to reveal the molecular structure and nuclear forces inside a typical molecule of a crystal. Many techniques, like X-ray crystallography and NMR spectroscopy, are widely used in chemistry and biochemistry to determine the structures of an immense variety of molecules, including inorganic compounds and bio-macromolecules.
  • Thin film production.

Massive production examples:

• "Powder salt for food" industry;
• Silicon crystal wafer production.
• Production of sucrose from sugar beet, where the sucrose is crystallized out from an aqueous solution.

Purification

Used to improve (obtaining very pure substance) and/or verify their purity.

Crystallization separates a product from a liquid feedstream, often in extremely pure form, by cooling the feedstream or adding precipitants which lower the solubility of the desired product so that it forms crystals.

Well formed crystals are expected to be pure because each molecule or ion must fit perfectly into the lattice as it leaves the solution. Impurities would normally not fit as well in the lattice, and thus remain in solution preferentially. Hence, molecular recognition is the principle of purification in crystallization. However, there are instances when impurities incorporate into the lattice, hence, decreasing the level of purity of the final crystal product. Also, in some cases, the solvent may incorporate into the lattice forming a solvate. In addition, the solvent may be 'trapped' (in liquid state) within the crystal formed, and this phenomenon is known as inclusion.

Thermodynamic view

The nature of a crystallization process is governed by both thermodynamic and kinetic factors, which can make it highly variable and difficult to control. Factors such as impurity level, mixing regime, vessel design, and cooling profile can have a major impact on the size, number, and shape of crystals produced.

Now put yourself in the place of a molecule within a pure and perfect crystal, being heated by an external source. At some sharply defined temperature, a bell rings, you must leave your neighbours, and the complicated architecture of the crystal collapses to that of a liquid. Textbook thermodynamics says that melting occurs because the entropy, S, gain in your system by spatial randomization of the molecules has overcome the enthalpy, H, loss due to breaking the crystal packing forces:

T(Sliquid − Ssolid) > Hliquid − Hsolid

Gliquid < Gsolid

This rule suffers no exceptions when the temperature is rising. By the same token, on cooling the melt, at the very same temperature the bell should ring again, and molecules should click back into the very same crystalline form. The entropy decrease due to the ordering of molecules within the system is overcompensated by the thermal randomization of the surroundings, due to the release of the heat of fusion; the entropy of the universe increases.

But liquids that behave in this way on cooling are the exception rather than the rule; in spite of the second principle of thermodynamics, crystallization usually occurs at lower temperatures (supercooling). This can only mean that a crystal is more easily destroyed than it is formed. Similarly, it is usually much easier to dissolve a perfect crystal in a solvent than to grow again a good crystal from the resulting solution. The nucleation and growth of a crystal are under kinetic, rather than thermodynamic, control.

Equipment for crystallization

1. Tank crystallizers. Tank crystallization is an old method still used in some specialized cases. Saturated solutions, in tank crystallization, are allowed to cool in open tanks. After a period of time the mother liquid is drained and the crystals removed. Nucleation and size of crystals are difficult to control. Typically, labor costs are very high.

2. Scraped surface crystallizers. One type of scraped surface crystallizer is the Swenson-Walker crystallizer, which consists of an open trough 0.6 m wide with a semicircular bottom having a cooling jacket outside. A slow-speed spiral agitator rotates and suspends the growing crystals on turning. The blades pass close to the wall and break off any deposits of crystals on the cooled wall. The product generally has a somewhat wide crystal-size distribution.

3. Double-pipe scraped surface crystallizer. Also called a votator, this type of crystallizer is used in crystallizing ice cream and plasticizing margarine. Cooling water passes in the annular space. An internal agitator is fitted with spring-loaded scrapers that wipe the wall and provide good heat-transfer coefficients.

4. Circulating-liquid evaporator-crystallizer. Also called Oslo crystallizer. Here supersaturation is reached by evaporation. The circulating liquid is drawn by the screw pump down inside the tube side of the condensing stream heater. The heated liquid then flows into the vapor space, where flash evaporation occurs, giving some supersaturation.The vapor leaving is condensed. The supersaturated liquid flows down the downflow tube and then up through the bed of fluidized and agitated crystals, which are growing in size. The leaving saturated liquid then goes back as a recycle stream to the heater, where it is joined by the entering fluid. The larger crystals settle out and slurry of crystals and mother liquid is withdrawn as a product.

5. Circulating-magma vacuum crystallizer. The magma or suspension of crystals is circulated out of the main body through a circulating pipe by a screw pump. The magma flows though a heater, where its temperature is raised 2-6 K. The heated liquor then mixes with body slurry and boiling occurs at the liquid surface. This causes supersaturation in the swirling liquid near the surface, which deposits in the swirling suspended crystals until they leave again via the circulating pipe. The vapors leave through the top. A steam-jet ejector provides vacuum.

6. Continuous oscillatory baffled crystallizer (COBC). The COBC is a tubular baffled crystallizer that offers plug flow under laminar flow conditions (low flow rates) with superior heat transfer coefficient, allowing controlled cooling profiles, e.g. linear, parabolic, discontinued, step-wise or any type, to be achieved. This gives much better control over crystal size, morphology and consistent crystal products. For further information see oscillatory baffled reactor.

Sealing is the process to cover the floor in a way that is even with no scratches and permable . Generaly this process involves the use of chemicals like Polyurethane or commonly known as "Wood Sealer"

After all the dust has been cleaned there is when several coats of sealer needs to be applied. Usually is better not to have any traffic on the floor for a couple of days so that the sealing can dry naturally.

Grout is a construction material used to embed rebars in masonry walls, connect sections of pre-cast concrete, fill voids, and seal joints (like those between tiles). Grout is generally composed of a mixture of water, cement, sand and sometimes fine gravel (if it is being used to fill the cores of cement blocks). Sometimes color tint is applied as a thick liquid and hardens over time, much like mortar.

It is also a component of mosaics. Although ungrouted mosaics do exist, most have grout between the tesserae.

Main varieties include: tiling grout (either urethane, cement-based or epoxy), flooring grout, resin grout, non-shrink grout and thixotropic grout.

There are a few tools associated with applying and removal of grout such as:

• grout saw or grout scraper; a manual tool for removal of old and discolored grout. The blade is usually composed of tungsten carbide.
• grout float; A trowel-like tool for smoothing the surface of a grout line, typically made of rubber or soft plastic.
• grout sealer is a water-based sealant applied over dried grout that resists water, oil and acid-based contaminants.
• Dremel grout attachment; an attachment guide placed over a Dremel rotary tool for faster removal of old grout than a standard grout saw.

Hydrocleaning, high pressure cleaning or waterblasting is the use of water propelled at high speeds to clean surfaces and materials. By focusing and pressurizing the water stream, the force generated can remove, for example:

• Paint from walls, metal, and highways
• Rubber from runways (airfield rubber removal)
• Sealants and membranes from concrete
• Gum from side walks

Pressures

In order to standardize cleaning operations and surface preparation specifications the Steel Structures Painting Council (SSPC) has adopted the following four definitions for cleaning operations using water jetting technology:

• Low-pressure water cleaning (LP WC) is the use of water pressure less than 5,000 psi (34 MPa) for cleaning.
• High-pressure water cleaning (HP WC) is the use of water pressure between 5,000 to 10,000 psi (34 to 70 MPa) for cleaning.
• High-pressure water jetting (HP WJ) is the use of water pressure between 10,000 to 25,000 psi (70 to 170 MPa) for cleaning.
• Ultrahigh-pressure water jetting is the use of pressures above 25,000 (170 MPa) for cleaning.

Applications

Surface preparation

Any time a hard surface, such as asphalt, concrete or metal, needs to have a coating applied, the surface must first be prepared. The use of high pressure and ultra high pressure water has been used to prepare various surfaces for the purpose of repair and reapplication of such coatings. Coatings are used to protect concrete from the elements, rain, salt, and to create a friendlier surface for human use. Concrete can also be covered with carpet or tiles using a heavy duty glue or mastic. Asphalt and concrete can be painted to communicate acceptable travel patterns, potential hazards, or for aesthetics. High pressure water can be used to clean these materials off when new ones are desired.

High pressure water has been used to remove:

• Membranes:
  • Elastomeric
  • Rubber
  • Urethane
  • Hot applied
• Paint from:
  • Highways
  • Runways
  • Parking structures
  • Metal surfaces

Airfield rubber removal

Commercial and military airports are required to keep certain levels of friction on the landing strips in order to prevent planes from skidding off. Runway design, weather and amount of rubber on the runway all play a role in the level of friction of a landing strip. If too much rubber is present, especially in rainy weather, the friction of the landing strip will be lower requiring more distance for the plane to land. High pressure water can be used to remove rubber left from airplane tires and restore required friction levels. The level of use, number of landings, determines how often each runway needs to be cleaned. This process of removal is sometimes known as Airfield rubber removal.

General surface cleaning

High pressure water can be used to clean a multitude of surfaces dirtied by gum, pollution or graffiti.

We offer every type of Floor repairing, from the smallest dent to total reconstruction so that your floor can maintain the quality an beauty during its years of use.

Carpet cleaning, for beautification, and the removal of stains, dirt, grit, sand, and allergens can be achieved by several methods, both traditional and modern. Clean carpets are recognized by manufacturers as being more visually pleasing, potentially longer-lasting and probably healthier than poorly maintained carpets.

Currently, steam-cleaning is the most popular and widely accepted process, the other methods also have their merits. Carpet cleaning chemical manufacturers have been creating new carpet care technologies for over 20 years. Encapsulation dry-cleaning and green-based chemicals are some of the more recent developments from the carpet cleaning industry.

The professional carpet cleaning industry is primarily educated and unofficially governed by The Institute of Inspection, Cleaning, and Restoration Certification (IICRC). It is a nonprofit certifying body for the specialized fabric cleaning industry that sets modern carpet cleaning standards. It accepts five basic professional cleaning methodologies.

Steam-cleaning

Steam-cleaning or hot water extraction initially involves the application of a detergent based solution. After appropriate dwell time, a pressurized manual or automatic cleaning tool (such as a wand) passes over the surface several times to thoroughly rinse out all residue and particulates.

Heavily soiled areas require the application of pretreatments, preconditioners, or "traffic-lane cleaners", which are detergents or emulsifiers that break the binding of soils to carpet fibers over a short period of time, are commonly sprayed onto carpet prior to the primary use of the dry-cleaning system. One chemical dissolves the greasy films that bind soils and prevent effective soil removal by vacuuming. The solution may add a solvent like d-limonene, petroleum byproducts, glycol ethers, or butyl agents. The amount of time the pretreatment "dwells" in the carpet should be less than 15 minutes, due to the thorough carpet brushing common to these "very low moisture" systems, which provides added agitation to ensure the pretreatment works fully through the carpet.

Post-extraction is by far the most important step in the hot water extraction process. Since the hot water extraction method uses much more water than other methods like bonnet or shampoo cleaning, proper post-extraction is critical to avoid over saturation. When carpet is saturated there is a risk that soils and residue from deep in the carpet fiber and backing will wick up to the surface resulting in browning.

Dry-cleaning

Many dry carpet cleaning systems rely on specialized machines; Dry carpet cleaning machines include those manufactured by Brush and Clean, Host Dry, and Whittaker System. Dry carpet cleaning systems are mostly technically "very low moisture" (VLM) systems, relying on dry compounds complemented by application cleaning solutions, and are growing significantly in market share due in part to their very rapid drying time, a significant factor for 24-hour commercial installations. Dry-cleaning and "very low moisture" systems are also often faster and less labor-intensive than wet-extraction systems.

Dry compound

An absorbent, biodegradable powder and cleaning compound may be spread evenly over carpet and brushed or scrubbed in. For small areas, a household hand brush can work such a compound into carpet pile; dirt and grime is attracted to the compound, which is then vacuumed off, leaving carpet immediately clean and dry. For commercial applications, a specially designed cylindrical counter-rotating brushing system is used, without a vacuum cleaner. Machine scrubbing is more typical, in that hand scrubbing generally cleans only the top third of carpet.

Encapsulation

In the 1990s, new polymers began literally encapsulating (crystallizing) soil particles into dry residues on contact, in a process now regarded by the industry as a growing, up-and-coming technology; working like "tiny sponges", the deep-cleaning compound crystals dissolve and absorb dirt prior to its removal from the carpet. Cleaning solution is applied by rotary machine, brush applicator, or compression sprayer. Dry residue is vacuumable immediately, either separately or from a built-in unit of the cleaning system machine. According to ICS Cleaning Specialist, evidence suggests encapsulation improves carpet appearance, compared to other systems; and it is favorable in terms of high-traffic needs, operator training, equipment expense, and lack of wet residue. Encapsulation also avoids the drying time of carpet shampoos, making the carpet immediately available for use.

The use of encapsulation to create a crystalline residue that can be immediately vacuumed (as opposed to the dry powder residue of wet-cleaning systems, which generally requires an additional day before vacuuming) has recently become an accepted method for commercial and residential carpet maintenance.

Bonnet

After club soda mixed with cleaning product is deposited onto the surface as mist, a round buffer or "bonnet" scrubs the mixture with rotating motion. This industry machine resembles a floor buffer, with an absorbent spin pad that attracts soil and is rinsed or replaced repeatedly. The bonnet method is not strictly dry-cleaning and involves significant drying time, and usually only addresses the top third of carpet, making it a quick solution rather than a deep cleaning of dirt or odor as considered suitable for valuable carpet. To reduce pile distortion, the absorbent pad should be kept well-lubricated with cleaning solution.

Shampoo

Wet shampoo cleaning with rotary machines, followed by thorough wet vacuuming, was widespread until about the 1970s, but industry perception of shampoo cleaning changed with the advent of encapsulation. Hot water extraction, also regarded as preferable, had not been introduced either. Wet shampoos were once formulated from coconut oil soaps; wet shampoo residues can be foamy or sticky, and steam cleaning often reveals dirt unextracted by shampoos. Since no rinse is performed, the powerful residue can continue to collect dirt after cleaning, leading to the misconception that carpet cleaning can lead to the carpet getting "dirtier faster" after the cleaning.

When wet shampoo chemistry standards converted from coconut oil soaps to synthetic detergents as a base, the shampoos dried to a powder, and loosened dirt would attach to the powder components, requiring vacuuming by the consumer the day after cleaning.

Household processes

Other household carpet cleaning processes are much older than industry standardization, and have varying degrees of effectiveness as supplements to the more thorough cleaning methods accepted in the industry.

Vacuum

Vacuum cleaners use air pumps to create partial vacuums to suck up dust and dirt, usually from floors and carpets. Filtering systems or cyclones collect dirt for later disposal. Models include upright (dirty-air and clean-air), canister and backpack, wet-dry and pneumatic, and other varieties. Robotic vacuum cleaners have recently become viable as well.

Vacuum cleaner manufacturers are widespread and include Aerus LLC, Bissell Carpet Sweepers, Black & Decker DustBuster, Dirt Devil, Dyson, Electrolux, Eureka, Goblin Vacuum Cleaners, the Hoover Company, the Kirby Company, Nilfisk-Advance, Numatic International Limited, the Oreck Corporation, Regina Vacuum Cleaners, Rexair LLC, Samsung Electronics, Sebo Vacuum Cleaners, Tacony Corporation, Vax Vacuum Cleaner Ranges, Vorwerk, Wertheim Vacuum Cleaners,

Stain removal

Tea leaves and cut grass were formerly common for floor cleaning, to collect dust from carpets, albeit with risks of stains. Ink was removed with lemon or with oxalic acid and hartshorn; oil with white bread or with pipe clay; grease fats with turpentine; ox gall and naphtha were also general cleaners. Ammonia and chloroform were recommended for acid discoloration. Benzine and alum were suggested for removing insects; diatomaceous earth and material similar to cat litter are still common for removing infestations.

It can to be said that some traditional methods of stain removal can remain successful in removing stains. In a society where we are 'mostly' aware that reducing our carbon footprint can have eco friendly beneficial consequences to the environment. Fortunately there are eco friendly products accessible to the professional carpet and upholstery cleaner that provide solutions other than harsh chemical methods alone. Such products work well with anti-allergen treatments that will kill house dust mites (sometimes referred to by allergists as HDM). Dust mites cause respiratory conditions and ill health. Whatever method of stain removal or anti-allergen treatment is decided the decision should be left with the individual. Quite rightly stains that are treated quickly will have a greater chance of removal. However a badly treated stain can become a permanent stain and caution should be addressed when treating natural fibres such as wool that may react differently to different treatments.

When dealing with stains time is a factor. The longer the stain material remains in the carpet the higher the chance of a permanent color change, even if all the original stain material is removed. Immediately blotting (not rubbing) the stain material as soon as possible will help reduce the chances of a permanent color change.

There are many stains that permanent stains, for example, any type of artificial food coloring stain is a permanent stain. Examples include: red kool aid, blue gatorade, green listerine, orange soda, purple soda, yellow soda, etc. However, these stains can be removed with a Heat Transfer Stain reducing method that incorporates a stain reducing chemical such as Pro's Choice Red 1. Do Not Attempt this process on your own! Only a carpet cleaning professional can produce professional results! You may end up burning your carpet if you attempt this method without any training or instruction.

Other

Carpet rods, rattan rugbeaters, and carpet-beating machines for beating out dust, and also brooms, brushes, dustpans, and shaking and hanging were all carpet-cleaning methods of the 19th century; brooms particularly carry risks of wear.

Misconceptions

The concept that walking barefoot on a carpet may lead to damage from body oils has not been supported or disproven by standardized reports or testing or by industry evidence