Abrasive Materials for Painting Preparation
Abrasive materials are used for preparing surfaces before redecorating them. For most purposes glass-paper is the most common abrasive material, and it is best used over a cork or wooden block as described in Interior Decoration: Preparation for Painting. Glass-paper is obtainable in many grades of coarseness and for most purposes the amateur will find grade middle-two most suitable for rubbing down. Worn pieces of grade middle-two glass-paper may be used instead of new pieces for rubbing down before applying finishing coats.
In addition to the ordinary type of glass-paper, a waterproof grade is obtainable. This may be used when cleaning the paintwork surfaces down with sugar soap as described in Interior Decoration: Preparation for Painting. The waterproof glass-paper does, in most cases, provide a smoother finish than the unwaterproofed grades. Of course, this type of preparation does require more time, but it is recommended for a superior quality finish.
As an alternative to glass-paper, garnet paper may be used. Garnet paper has tougher, sharper particles than glass-paper and will, of course, last longer. It is mostly used in preparing surfaces in the form of sanding discs which are fitted to electrical drills. Another abrasive for preparing interior surfaces for decorating is pumice-stone or pumice powder. Both are used with water as a lubricant and these abrasives may be used when an especially fine surface finish is required.
With all water-lubricated abrasives the treated surfaces should be well washed down to free them from grit and dust, and after rinsing, all surfaces for painting should be allowed to dry thoroughly before application of following coats of paint. This thorough-drying process is essential to good workmanship. If paint is applied on a damp or greasy surface it will deteriorate rapidly. The abrasive used for cleaning metal surfaces is emery cloth, which is also obtainable in a good range of coarseness.