Polish / Compound Abrasive Abilities
01-29-2007, 11:43 AM
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Polish / Compound Abrasive Abilities
Polish / Compound Abrasive Abilities:
The abrasion or cutting ability of a polish on a 0-10 scale; least abrasive to most, a rating of 0 would constitute a functionally nonabrasive material (i.e. diatomaceous earth or Kaolin) a 10 rating would be 800 + grit abrasive.
The most common abrasive used is silica however; many formulators are also using aluminium oxide. Most good compounds and polishes contain diminishing abrasives and are a combination of both aluminium oxide crystals and silicon carbide crystals. Think of them as liquid sandpaper, they are formulated with a lubricant, solvents, water and an abrasive 0.3 –0.4 micron minerals that diminishes with friction, buffered or cushioned in a lubricating oil film, usually in a semi-liquid paste.
Compounds - most good compounds are a combination of both silica and aluminium oxide. Some very abrasive compound polishes don’t feel abrasive to the touch because the particles are formulated in a water-in-oil emulsion and are not released without friction-heat.
The way a diminishing abrasive works; the abrasives start out aggressively (relatively large micro particles) removing surface defects. As the diminishing abrasives are subjected to heat (surface friction) and pressure, the micro abrasive size is constantly reduced. In this way it removes surface defects and burnishes the surface to remove any fine surface marks without scratching or scouring the finish the way a traditional compound would.
The solvents most commonly used are mineral spirits, kerosene, and naphtha. Mineral spirits is usually a quick-drying solvent that will make the compound dry quickly, speeding up the job. However, it will also increase the possibility of burning the paint if used incorrectly. Kerosene is a slower-drying solvent that reduces the tendency to burn paint. It will, however, increase the work time with the compound.
The paint film surface also requires occasional polishing to maintain a pristine paint film surface and to ensure that any accumulated microscopic contamination in the paint surface crevices does not cause paint staining and that this dirt is not sealed into the paint by the application of wax or sealant. The use of abrasive type polish / cleaners should always be restricted to specific problems. Most original paint finishes are tougher on the outer surface than the layers underneath. The outer layer (which contains the paints UVR protection) should be preserved as far as possible.
Never mix polishes on a foam pad, and never use a foam pad that has been used to apply a compound for polishing unless it has been thoroughly cleaned first.
Compounding, Polishing and Finishing are different polishing methods (stages) that do not necessarily need to be applied consecutively. The appropriate combination of polishing steps depends upon colour and quality of the paint surface; as well as the required quality of finished surface.
Bear in mind that a clear coat has a thickness of 1.5 – 2.0 Mils, removing more that 0.3 mil of clear coat will cause premature paint film failure. As a point of reference two sheets of Saran wrap placed on top of each other measure 1.5Mil a surface scratch that will `catch' your fingernail is approximately 0.04 Mils deep will usually require wet sanding and refinishing. There comes a point when you must judge wither removing a scratch will compromise the clear cot and if so you’ll have to ‘live’ with the imperfection (these can be aesthetically masked by using a Glaze)
Compound Polishing Surface Temperature - the temperature of a paint surface should be monitored when using a high-speed polisher, friction heat can cause a rapid temperature rise in the order of 20 oF (i.e. initial surface temp 80oF, heat attained with a cutting foam pad at 1,100 RPM for approx. ten seconds is approx. 104oF) the localized paint temperature should be limited to 110 oF. In accordance with the Society of Automotive Engineers (SAE) a temperature of 115 oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat.
Polish I (compound) - (800 -1000 grit) levels and removes heavy defects; compound polish removes severe paint flaws and wet sanding marks with suspended abrasives in a mix of oils/solvents/water, which also provides the pad with a lubricant to work it across the paint surface. This will leave behind surface marring or haze. CAS = 8/10
Polish II – (1200 grit) levels moderate to heavy defects; polish is again a mixture of abrasives and oils/solvents/water which also provides the pad with a lubricant to work it across the paint surface. This will remove the surface marring, hazed or swirls in the paint surface and restore full depth of shine and surface clarity. CAS = 7/10
Polish III – (1500 grit) levels light to moderate defects CAS = 6/10
Polish IV – (2000 grit) levels light defects and removes hazing CAS = 5/10
Polish V – (3000 grit) finishing has very minor corrective ability and burnishes paint to high gloss CAS = 3/10
Glaze – very sleight abrasive (Kaolin) usually with oils and wax to fill and add warmth/depth CAS = 2/10
1. The abrasive ability is approximately distributed, 60% abrasive ability of the product (grit number) 30% foam composition and 10% pressure applied and/or speed of rotation or oscillation.
2. Increase the aggressiveness of the product rather than go to a very aggressive pad
3. Always finish with the next lower level of abrasive i.e. after using a compound polish #1(800 -1000 grit) continue with polish # II (1200 grit) and then polish # III (1500 grit) and finally a IV 2000 grit or
# V 2500 grit polish, whatever grade you start with always finish with a the least abrasive polish
4. "Going through the grits" what does this mean?” no it’s not a reference to eating breakfast in Georgia! It refers to the process of using different grit finishing papers of progressively finer grit to get a smooth finish. By going through the grits each progressive piece of grit finishing paper removes the scratches from the previous.
5. Changing the size (surface area) of the pad increases its abrasiveness by concentrating pressure
(See also Comparative Abrasive Scale (CAS), Diminishing Abrasives, Machine Polish / Foam Pad Combinations, Polish)
The abrasion or cutting ability of a polish on a 0-10 scale; least abrasive to most, a rating of 0 would constitute a functionally nonabrasive material (i.e. diatomaceous earth or Kaolin) a 10 rating would be 800 + grit abrasive.
The most common abrasive used is silica however; many formulators are also using aluminium oxide. Most good compounds and polishes contain diminishing abrasives and are a combination of both aluminium oxide crystals and silicon carbide crystals. Think of them as liquid sandpaper, they are formulated with a lubricant, solvents, water and an abrasive 0.3 –0.4 micron minerals that diminishes with friction, buffered or cushioned in a lubricating oil film, usually in a semi-liquid paste.
Compounds - most good compounds are a combination of both silica and aluminium oxide. Some very abrasive compound polishes don’t feel abrasive to the touch because the particles are formulated in a water-in-oil emulsion and are not released without friction-heat.
The way a diminishing abrasive works; the abrasives start out aggressively (relatively large micro particles) removing surface defects. As the diminishing abrasives are subjected to heat (surface friction) and pressure, the micro abrasive size is constantly reduced. In this way it removes surface defects and burnishes the surface to remove any fine surface marks without scratching or scouring the finish the way a traditional compound would.
The solvents most commonly used are mineral spirits, kerosene, and naphtha. Mineral spirits is usually a quick-drying solvent that will make the compound dry quickly, speeding up the job. However, it will also increase the possibility of burning the paint if used incorrectly. Kerosene is a slower-drying solvent that reduces the tendency to burn paint. It will, however, increase the work time with the compound.
The paint film surface also requires occasional polishing to maintain a pristine paint film surface and to ensure that any accumulated microscopic contamination in the paint surface crevices does not cause paint staining and that this dirt is not sealed into the paint by the application of wax or sealant. The use of abrasive type polish / cleaners should always be restricted to specific problems. Most original paint finishes are tougher on the outer surface than the layers underneath. The outer layer (which contains the paints UVR protection) should be preserved as far as possible.
Never mix polishes on a foam pad, and never use a foam pad that has been used to apply a compound for polishing unless it has been thoroughly cleaned first.
Compounding, Polishing and Finishing are different polishing methods (stages) that do not necessarily need to be applied consecutively. The appropriate combination of polishing steps depends upon colour and quality of the paint surface; as well as the required quality of finished surface.
Bear in mind that a clear coat has a thickness of 1.5 – 2.0 Mils, removing more that 0.3 mil of clear coat will cause premature paint film failure. As a point of reference two sheets of Saran wrap placed on top of each other measure 1.5Mil a surface scratch that will `catch' your fingernail is approximately 0.04 Mils deep will usually require wet sanding and refinishing. There comes a point when you must judge wither removing a scratch will compromise the clear cot and if so you’ll have to ‘live’ with the imperfection (these can be aesthetically masked by using a Glaze)
Compound Polishing Surface Temperature - the temperature of a paint surface should be monitored when using a high-speed polisher, friction heat can cause a rapid temperature rise in the order of 20 oF (i.e. initial surface temp 80oF, heat attained with a cutting foam pad at 1,100 RPM for approx. ten seconds is approx. 104oF) the localized paint temperature should be limited to 110 oF. In accordance with the Society of Automotive Engineers (SAE) a temperature of 115 oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat.
Polish I (compound) - (800 -1000 grit) levels and removes heavy defects; compound polish removes severe paint flaws and wet sanding marks with suspended abrasives in a mix of oils/solvents/water, which also provides the pad with a lubricant to work it across the paint surface. This will leave behind surface marring or haze. CAS = 8/10
Polish II – (1200 grit) levels moderate to heavy defects; polish is again a mixture of abrasives and oils/solvents/water which also provides the pad with a lubricant to work it across the paint surface. This will remove the surface marring, hazed or swirls in the paint surface and restore full depth of shine and surface clarity. CAS = 7/10
Polish III – (1500 grit) levels light to moderate defects CAS = 6/10
Polish IV – (2000 grit) levels light defects and removes hazing CAS = 5/10
Polish V – (3000 grit) finishing has very minor corrective ability and burnishes paint to high gloss CAS = 3/10
Glaze – very sleight abrasive (Kaolin) usually with oils and wax to fill and add warmth/depth CAS = 2/10
1. The abrasive ability is approximately distributed, 60% abrasive ability of the product (grit number) 30% foam composition and 10% pressure applied and/or speed of rotation or oscillation.
2. Increase the aggressiveness of the product rather than go to a very aggressive pad
3. Always finish with the next lower level of abrasive i.e. after using a compound polish #1(800 -1000 grit) continue with polish # II (1200 grit) and then polish # III (1500 grit) and finally a IV 2000 grit or
# V 2500 grit polish, whatever grade you start with always finish with a the least abrasive polish
4. "Going through the grits" what does this mean?” no it’s not a reference to eating breakfast in Georgia! It refers to the process of using different grit finishing papers of progressively finer grit to get a smooth finish. By going through the grits each progressive piece of grit finishing paper removes the scratches from the previous.
5. Changing the size (surface area) of the pad increases its abrasiveness by concentrating pressure
(See also Comparative Abrasive Scale (CAS), Diminishing Abrasives, Machine Polish / Foam Pad Combinations, Polish)
Last edited by TOGWT; 01-30-2007 at 07:27 AM.
