PAINTING OREGON PINE

Evening Star, Issue 21081, 19 April 1932, Page 2

PAINTING OREGON PINE

PRODUCING THE BEST EFFECTS [By Ciias. E. Olxvku.] The application of paint or varnish to. Oregon pino and other coarse-grained softwoods of similar nature oilers some new problems to the painter. The beautiful grain marking to be seen in this wood has led to its extensive use for medium-class dwellings, public buildings and so on. When simply stained the effect is good, and the beauty of the grain enhanced, but -when painted or varnished the result is generally disappointing. No matter how many coats are applied, the effect in a very short time is entirely spoiled by the rising of the grain, accompanied in many instances by a series of longitudinal splits between the grain strata'. So many painters have experienced this trouble that wo deemed it worthy of a little attention, and the result of our investigation will, we hope, be of some value to our readers, and especially to those who have written to us upon the subject. The first point that will occur to one making a close examination of Oregon pine is that it consists of alternate layers of hard and soft grain loosely knit together. In many instances, due probably to the manner in which the wood is cut, the layers are not attached to each other, but lie upon each other like the scales of a fish, and these scales move upon each other with the expansion and contraction of the whole according to the presence or absence of moisture. So great is this movement that it may lead to a splitting of the hard grain and cause the longitudinal cracks to which we have referred. The soft part of the grain .readily absorbs the moisture, but the hard part of the grain is often so fully charged with resinous sap that oil paints are slow to dry upon it. To paint Oregon pine successfully is a four-fold problem. The various strata of hard and soft grains must be securely anchored together, the soft grain must be fully satisfied so that it cannot absorb moisture, the resinous face of the hard grain must bo broken to allow the paint adhesion, and the Vwhole surface must be filled and firmly set so that it will no longer show and can no longer move. The method by which this may be accomplish: 1 is a fairly simple one, and the materials necessary are readily available.

It will be obvious that a coat of -priming paint applied in the usual manner cannot accomplish all that is desired. It merely skims over the surface, leaving the soft- grain still not deeply satisfied, and docs little or nothing towards knitting the grains together or removing the resinous sap from the hard grain. Something more penetrating, more drastic in its application, is required. The basis of priming liquid will be three parts of boiled linseed oil, one part of goldsize, and one part of turpentine. This must be brushed freely on to the Oregon pine until the wood is saturated, then take a medium grade abrasive paper or some fine No. 2 sandpaper wrapped around a cork block and scrub the surface until the oil is absorbed or the grain can absorb no more. This scrubbing must be thorough, because upon it depends the working in of the oil mixture right into the fibre of the pine, and the removal of the resinous sap on the surface on the hard grain. When there are resinous pores showing on the pine the addition of a little benzol mixture to the oil is an advantage. After the oiling and scrubbing is completed wipo the surface with an old linen rag and leave it to dry. If these operations Jiavp been properly carried out the surface will bo level, and the absorption of the grains will now be even. The soft grain being fully satisfied with a drying oil will no longer absorb moisture.

When the oiling-in is quite dry apply a coat tjf white load priming paint, tinted with red lead and made up in equal parts of- linseed oil and turpentine, kept fairly stout and brushed out well to obtain a good sturdy coat free from any tendency to skin dry. Upon this coat the stopping and filling up will be done. For the stopping use paste wliit9 load stiffened, with dry sifted whiting. For the filling or facing up use paste white lead, dry sifted whiting, and sufficient golclsizo to make an easy knifing paste for application with the broad knife. Do not plaster on the filling, but keep the knife pressed close to the surface, leaving the filling only where it is required to level up the hollows. Allow the filling plenty of time to harden, then rub down the whole surface ready for the final coats of paint. Under the new White Lead Act you are not allowed to do dry sandpapering on white, lead paint, and the advice to use waterproof sandpaper and water upon woodwork that is only pyotected by one or two coats of paint is altogether misleading, and likely to cause more damage than it can do good. You know bow readily the edges and ledges will rub through to the wood, and although in this case we are well protected from tho water by the oiling of the wood, still wo think the water rubhind is a practice that should not he adopted except for rubbing down old paint surfaces, or for gently flatting clown the last coat but one. when there is ample protection and little fear of rubbing through. For tho water, then, we will substitute turpentine, with a little raw linseed oil added to lubricate the surface and prevent too rapid evaporation of the turps. This may he applied by moans of a wad of old linen, doing a small section, at a time, sandpapering immediately and wiping off as you go, thus avoiding leaving tho rubbing.liquid on 100 long or going over the same plaeo too often with the danger of softening the filling and priming coat. Wo can recommend this method in the place of water rubbing on primings and after burning off old paint, nr wherever there is danger of the water reaching tho wood.