Buffing compound is a material used in polishing operations which must be removed once polishing is complete. Buffing compound consists of a finely divided abrasive mixed with a “vehicle” which is often a paraffin or, in some cases, animal fat and other “fats” depending on their price and availability in a particular region of the world. The “vehicle” performs many functions –
- It holds the abrasive (which would otherwise be a powder) together so that it can be easily handled.
- It acts as a lubricant to help minimize heating of parts due to friction during the buffing operation (more on that later).
- Most “vehicles” (especially paraffin) have a relatively high heat capacity and a high heat of fusion. This, too, contributes to heat moderation during the buffing process.
In use, buffing compound is applied to a spinning wheel made of fabric or some other soft, plyable material. This is accomplished either by rubbing the wheel with a “stick” of the solid material or by spraying the wheel with a liquid formulation which may be an emulsion. The wheel is porous so that it will absorb or capture the buffing compound as it is applied. Parts to be polished are brought into contact with the spinning wheel covered with the abrasive compound. Polishing is achieved through a combination of cutting and smearing as the part is brought into contact with the buffing wheel.
Once the polishing operation is complete, excess buffing compound must be removed. Its removal is made difficult by the fact that during the buffing operation, considerable heat is produced by friction as the wheel spins against the part. Although helpful, the lubrication provided by the buffing compound vehicle (as stated above) is not sufficient to eliminate heating which is an unavoidable consequence of the buffing operation. No matter what the original buffing compound formulation was, the result of degradation due to heat during buffing is more than likely a hydrocarbon with a high melting temperature.
There are many cleaning formulations designed to remove buffing compound residues. The majority are soaps which attack the hydrocarbon residue. In some cases, the effectiveness of these formulations are limited by the concentration of solids consisting of the original abrasive and whatever material has been removed from the part by buffing.
But the real keys to successfully removing buffing compound residues are temperature and timeliness. Even the most aggressive soap, is not likely to saponify or emulsify a hydrocarbon in its solid state. Operating at a temperature sufficient to melt the hydrocarbon, then, is an absolute necessity. In most cases, the minimum temperature for successful buffing compound removal is the neighborhood of 160 to 180°F. This is despite the fact that the original formulation may melt at a much lower temperature before use. As for timeliness, it is difficult to overstate the importance of cleaning buffed parts as soon after buffing as possible – even before they have cooled if it is possible. As it ages, the volatile components of the buffing compound evaporate. The remaining solids bond to each other to form a rock-like material that makes them all but impossible to remove. Even in a continuous process, provision should be made to prevent the accumulation of uncleaned buffed parts over a holiday or a weekend for example.
Finally, and this may lead to some controversy, in my experience, precleaning of buffed parts, especially by soaking, is not a good idea. This is especially true in the case of vehicles which contain animal fats that tend to turn gelatinous with heat and time. I’m not sure if this happens because the animal fats “cook” or what, but I have on many occasions seen the effect. For best results, cleaning, once initiated, should be brought to a timely conclusion with the application of aggressive mechanical means (spraying, turbulation or ultrasonics) in a single step and without presoaking.
– FJF –
2 comments on “Buffing Compound Removal – A Unique Challenge”
Thanks Bill! You comment is appreciated – FJF
Hello John, There is a bi-chemical immersion process we’ve had success promoting. And in many cases, it will overcome the timeliness concern addressed in your post. Stage #1 consists of a bio-based solvent designed to dissolve paraffins common in the binder system. Stage #2 uses an inhibited alkaline cleaning solution that saponifies any fatty acids also seen in binder system. Stage #3 (and optionally #4) are hot water rinse steps. The chemistry in Stage #1 is truly the difference maker. Together with the appropriate agitaiton (preferrably u/s) and tempertures throughout, buffing compound removal – in any condition – is possible. Bill Breault, Petroferm.