TYPE OF PAINT
Alkyd or vinyl base paints are preferred. Alkyds are oil-solvent synthetic paints. Vinyls are often called "latex" paints and are water soluble as emulsions. Both have excellent qualities for indoor use but must be specially formulated for outdoor work. The water base vinyls are not generally used on metal screen towers because of the possibility of rust formation. They also require that the old painted surfaces be in good condition. Alkyds, on the other hand, since they are oil based cannot cause rust on a metal surface and are not quite so "choosy" about the undercoating. If moisture can find its way through the screen tower -- from the top or through the rear -- and causes blisters with oil paints, then it is best to use vinyl or latex paints because these surfaces are somewhat porous and can actually breathe. Moisture actually will find its way out through the surface!

APPLICATION
On previously painted surfaces a very thorough sanding or scraping is necessary. Loose or blistered paint must be removed. When too many coats have built up through the years then it sometimes becomes necessary to remove all the old paint by sand blasting or chemical means.

PREPARATION
Plywood-- Even though of Marine grade and rated waterproof, plywood sheets, when new must be treated with a prime coat of a special outdoor plywood sealer. Two coats of screen paint are then required. If, after many coats of paint, there is trouble with pooling, alligatoring, or blistering then it is wise to sand well and apply outdoor plywood sealer before the finish coats of paint.

Galvanized Metal-- This is a zinc coating on iron or steel and is quite resistant to the weather if left uncoated, but it must be painted with a reflective surface. Since certain metallic pigments in paint react with zinc and will, in time, lose its bond, it is recommended that galvanized sheet be first "pickled" or surface-etched with vinegar or mild acetic acid. THIS ACID WASH MUST BE REMOVED WITH CLEAR WATER. Then the surface is primed with commercially available Zinc Chromate Primer, a yellow, fast drying prime which will be a barrier coat for the finish paint and prevent galvanic action from adversely affecting adhesion. This treatment is necessary only when the sheet is new and before it is painted for the first time. It is not used again -- except that if scraping in future years does expose the bare metal then the bare spots should be again primed with Zinc Chromate.

Iron or Steel Sheet-- For best results two coats of paint should be applied. One gallon of properly formulated drive-in screen paint will cover approximately 350 sq. ft. The spreading rate will vary somewhat depending on the condition of the old surface and the technique of application. To prevent running short of paint on the job it is recommended that 250 sq. ft. be allowed in figuring quantity.

High density paints are available which have a very heavy body and which are applied as received with a lamb's wool roller only. This gives a stipple or orange peel effect that prevents rain streaks from looking glossy -- but this finish also picks up more dust and dirt. It also builds up a heavier coat of paint which in the long run can be a problem.

With paints of normal density brush, roller or spray can be used. Alkyd paints can be thinned with turpentine or mineral spirits. Vinyl and latex paints are thinned with water only. Up to 10% thinners can be added but much depends upon the technique of the contractor's application.