primer and red iron-oxide, zinc-oxide, linseed-oil primer. These primers do not contain toxic lead or
chromate pigments, but some corrosion protection has been sacrificed.
(a) Zinc-molybdate primer. Zinc-molybdate primer (alkyd type) is designed for use on
steel (cleaned to a commercial-blast grade or better) and aluminum. This primer has low VOC content.
(b) Red iron-oxide, zinc-oxide, linseed-oil primer. This primer replaces red lead-based
primer. It is designed for use on steel that has been cleaned with hand tools.
d. Size. Size is used to fill the pores of plaster or wallboard so that paint will stay on the
surface. There are several types of size available, but the main types are glue-water and thinned varnish.
Prepare varnish size by thinning 1 gallon of varnish with 1 quart of turpentine. Prepare glue-water size
by mixing glue and water until the mixture will spread easily. Primers and sealers have been improved
to the extent that size is seldom needed for paint preparation today.
e. Wood Filler. Wood filler provides a smooth, even finish on wood that has open grain, such
as walnut, mahogany, and oak. Paste wood fillers are usually made of silex or silica ground in linseed
oil and lacquer drier with various pigments added for color. Fillers come in standard colors, such as
mahogany, light oak, dark oak, maple, walnut, black, white, and natural.
Most fillers come in paste form and are too thick to be used without thinning. Thin filler by adding
turpentine, naphtha, or a special thinner according to the instructions on the container. About 12 pint of
thinner to 1 pound of filler is required for coarse, open-grained woods. Closer grained woods, such as
walnut, rosewood, mahogany, and zebrawood, require a mixture of about 10 ounces of thinner to 1
pound of filler. When you are mixing filler, add a little thinner at a time until you can get the desired
f. Plastic Wood. Plastic wood is used to fill holes in wood, especially if the finish is to be clear.
It is available commercially and can be purchased in various quantities. This filler dries very rapidly
and must be kept in airtight containers.
g. Caulking Compound. Caulking compound is used to seal joints around doors and windows
and between baseboards and wallboards. It usually contains asbestos fiber, a pigment for opacity, fish
or soybean oil, and a drier. Caulking compound will remain elastic for some time; this allows it to
expand and contract with the movement of the building. There are two main types of caulking
compound: the gun type, which is forced into cracks and crevices in ribbonlike form, and the knife type,
which is applied with a putty knife. Caulking compound can also be used as a window-sash putty, and it
is available in rolls or strips that are applied by pressing them into joints.
h. Putty. Putty is used to fill holes in surfaces and to replace checked or broken putty around
windows. Commercial putty is made of white alkyd and whiting combined with linseed oil and a neutral
oil to prevent it from drying too rapidly. Occasionally, you may substitute plastic wood for putty when
filling holes in wood.