|SOME SURFACES NEED SPECIAL
Gold leaf of good grade is one of the very few sign materials, which, by ifs very nature, cannot contribute to the premature breakdown Of sign or lettering work. When breakdown occurs, with its consequent dissatisfaction, the trouble is always found in one, or both of two causes:
(1) improper or insufficient preparation of the surface, or (2) faulty methods of laying. Of the two, particularly in outside work, improper preparation is by far the more common and serious. Adequate preparation of the proper kind is absolutely essential to good gold work. It is the basis of everything. Without it, signs cannot hope to stand up or look well.
The following suggestions will help you to start your signs right.
Galvanized Iron or Zinc
Put one-half ounce, each, of copper chloride, copper nitrate and sal ammoniac in a glass jar. Add one quart soft water. Stir with wooden paddle until dissolved. Then add, slowly, one-half ounce of muriatic acid. Apply to metal surface with a broad flat brush. When the first tone, black, has changed to gray, the metal is ready for the priming coats. This treatment will kill corrosion and keep it from working through the paint and gold leaf. It will also remove any traces of grease on the metal. Apply one coat of red lead, brushing out well. . Then apply one or, better still, two coats of white or yellow lead. Allow each coat of lead to dry thoroughly before sizing and laying. There are many new synthetic lacquers and primers suitable for the above work, but in any case these surfaces should be prepared in exactly the same manner as you would for a permanent paint job.
NOTE: Some sheet metals require special treatment as a preparation for painting. When working with any "trade name" sheet metal, therefore, you should get the advice of the manufacturer or dealer as to what treatment is necessary to insure good results.
All lead surfaces should be washed with a very weak solution of muriatic acid or sand blasted to give it "tooth." Apply slow oil size directly to the lead. Gild when proper tack is reached.
Cast aluminum letters and plaques should be coated both front and back. Satisfactory results may be obtained with any good commercial metal primer as a first coat and one or two coats of white lead and oil paint. Slow-drying oil size is to be applied to the well dried final coat. Utmost precaution must be taken during sanding to preserve primer and finish coat on sharp edges and points.
Wooden Surfaces and Wooden Letters
The essential object here is to seal the wood thoroughly so that moisture cannot get in from any direction. If moisture gets into the wood, it will not only shorten the life of the wood itself but will work under the paint and gold and literally "push them off." To prepare a wooden surface, prime it with 1-3 coats of burnish sealer. Avoid shellac, except to seal bleeding knots. Allowing plenty of time for drying between coats and sand papering between coats, apply one coat of good spar varnish and, when thoroughly dry, gild with slow size.
It is vitally important that all surfaces be painted this way. It is just as important to paint the back of wooden letters as it is the front.
Stone or Marble
It is necessary to stop the suction before sizing this type of material. Do this with one or two coats of shellac or varnish. Then. put on one coat of quick, hard-drying color. Size with "slow" oil size and gild the same as you would any other surface work.