Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/152

144 conditions. Judgment must be exercised in studying the surface and treating the same according to its needs.

The following suggestions as to repainting a cracked or peeled surface will meet the most common of both found in the general run of painting.

The preparation of a surface before painting is one of the most important matters to be considered. Properly preparing the surface will often go a great way in assisting to make a successful job of painting over a very badly cracked or peeled surface.

To properly clean a surface, it should be scraped and carefully gone over with a wire brush. The kit should consist of a good scraper and two wire brushes, one stiff and coarse, the other fine and soft. On a surface where the cracks are small and fine, a soft brush will assist in cleaning the dirt from the cracks and leaving the surface in better condition than will a coarse brush. On a surface with large cracks or a peeled surface, a coarse, stiff brush will assist in forcing off the scales, also breaking the peeled edges that have begun to turn out and are sometimes very hard to break loose.

The amount of turpentine recommended in the following reductions is based upon a gallon of hand mixed or prepared paint of a full linseed oil reduction.

Cracked Surfaces. When the paint is cracked in small hair lines, it is usually called crazing of the paint. Generally these hair lines run crosswise of the grain the entire width of the boards to which the paint is applied. The paint is invariably very hard and this crazing is often attributed to an excess of zinc. It is usually caused from an improper reduction or combination of pigments which do not dry uniformly, one being more easily affected by heat and cold than the others, thereby leaving a paint surface which is not uniform as to contraction and expansion. This trouble is especially noticeable on parts of work that have to withstand a great deal of vibration. If the paint has not