THE OWNER BUILT HOME & HOMESTEAD
(Page 9 of 13)
September/October 1972
By Ken Kern
Nothing much has really changed today in the painting industry from the formation of the first medieval closed shop. Modern house painters have their own particular brand of price-fixing exclusiveness; and their union, too, is careful to enforce maximum-size brush widths and to outlaw fast-working renegade spray or roller equipment. Thank God, a man may still work on his own home. And thanks to a tremendous chemical advance in recent years with unbiased reports from countless agencies, the "secrets of the mistery" are no longer the private property of an inner circle!
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The chemical advance has been very rapid. It has not been long since a painter himself mixed and ground his paints. His pigment was first zinc, then the improved titanium dioxide—first used in 1920. From earliest days he had used linseed oil as binder or vehicle.
Then in 1930 we had what is known in the industry as the alkyd revolution. Alkyd resin has all but replaced linseed oil in commercially prepared paints. More recently the synthetic paint industry has developed other remarkable vehicles such as phenolics, vinyls, urethanes, silicones, epoxies, acrylics and latex.
Exterior wood siding should not have to be painted less than six years after the first application. Planed lumber requires more frequent treatment than rough-sawn or rough-planed wood. As a matter of fact, rough-sawn redwood and cedar weather beautifully without any preservation whatever. Experimentally-minded home builders have found that any number of natural finishes can be concocted from readily available inexpensive materials. To create an aged-appearing flat finish, a mixture of discarded crankcase oil and gasoline has been used with success on roughsawn siding. A mixture of creosote and pigment-stain is another often-used natural finish. After several years a second coat of clear creosote and oil mixture is applied to restore protective qualities.
Conventional exterior paint uses titanium dioxide as the white paint-solid, and linseed oil and mineral spirits as the nonvolatile and volatile ingredients of the vehicle. But alkyds are more stain-and-blister-and-mildew-resistant than linseed oil paints. The finish coat should have zinc oxide pigments in it to control the rate of chalking. As a paint ages it collects dirt, changes color, and chalks. If the paint is correctly controlled, rain will wash off the dirt along with the chalking. The chalking effect is thus utilized to keep the paint cleaner and brighter, and so to prolong its usefulness. Applying a prime coat of shellac or aluminum paint over knotholes and flat-grained siding is an especially good practice.
Lacquer and varnish films break down sooner on outside exposure than do regular paints having protective pigments. The use of three coats of a high grade spar varnish is a minimum requirement for an outside transparent finish. Butyl phenol resin-based varnishes are definitely superior to the old type in hardness, durability and water resistance.
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