We have a building with 20 year old western redcedar clapboard siding that has never been stained or painted. The softer parts of the annual rings have been weathered away so the wood is very rough. The intent is to stain the siding with an oil-based semi-transparent stain.
Have been advised to pressure wash the siding before staining to remove mildew and dirt- and have been told not to pressure wash due to further eroding the clapboards’ surfaces, driving water behind the siding and so wetting the siding that it will cup or curl – not to mention the drying time.
What’s best?
Replies
orbital sander medium grit
unfortunately a lot of medium grit.
A hand grinder with a sand disc is easier if you can carry a light touch while handling it.
Edited 5/16/2002 12:02:52 PM ET by rez
don't pressure wash any wood imho...
Wet the whole side your going to start with. Hand wash with bleach and detergent. Start at the bottom and work your way up. Keep it wet as you work. If the siding starts to dry as you are washing, it will suck the dirt back in further. Rinse often and point the water down. Let it dry a few days and stain. Old Pro, not quite old, not quite pro, but closer every day on both...
The softer parts of the annual rings have been weathered away
The presure washer will triple the weathering in a day. eating the soft growth for a snack.
Whoever told you to pressure wash must have finished up their last pipe of crack too soon. Every cedar supplier and organization that I've ever seen (and every set of instructions from paint manufacturers to siding manufacturers), is very clear that you should NOT pressure wash cedar; it's just too delicate. We've had excellent experiences with basically using water and a medium or soft NON-wire brush (nylon or natural), and then washing and brushing the siding to remove loose paint. Follow this up with any sanding that needs to be done. Once dry, prime, caulk, then paint with two coats of a top quality paint (Ben Moore, SW, Pratt and Lambert, etc.), or one of those companies stains and a topcoat. Buy a $5 rock for whoever mentioned pressure washing to get them out of the way, roll up your sleeves, and do it right.
I agree about not pressure washing it.
But I wonder if he should use oxalic acid on it if he does not sand the whole surface.
It has weathered for 20 years without ANY finish and the surface would be fairly damaged and I wonder if it would take the stain.
in my not so humble opinion, NEVER pressure wash wood. This is true weather it is siding, fencing, a deck, or a birdhouse. Now, that being said, it is ok to USE a pressure washer to wet, soap or rinse with the machine, BUT you should not use any pressure. As pointed out, the pressure washer is hell on wood fiber.
The waterborne detergents and bleaches (oxalic acid is ok for some uses) will kill and loosen mold, moss and algae. Remove these by scrubbing with a brush during the rinsing. The key is to get the wood wet and keep it so before applying cleaners and all during the process. Don't tackle any thing but small patches that can be worked in twenty or thirty minutes. It takes at least ten minutes for the chems to work their magic, and it is important for them to do the work. Keep misting as you go (or work in the rain) being carefull not to let the wood dry or rinse off all your chemicals. Start at the bottom and work your way up to eliminate the running and staining of the released dirt.
The post said stain if I am correct (damn new boards) and wood to be stained does not nessatate (spelling) sanding. Old Pro, not quite old, not quite pro, but closer every day on both...
dad- I was wondering how far into the exposed unprotected 20 year cedar the oil stain would penetrate. I am concerned that the damaged surface fibers would take the bulk of the stain and minimize the protection to the siding itself. My thoughts on a light sanding were to remove the topmost worn surface to ease the oil into the good pores. However after the 20 years it sounds as if the cedar has a desirable well worn patina I myself would be hesitant to alter if the desired protection can be gained without the touch sanding.
Without seeing your siding I'd say; "I would not sand". But I haven't seen it so you'll have to be the judge and executioner. After twenty years that wood is dry and the stain should go deep. Test a small portion behind the bushes to see. I think sanding is only for surface smoothness and won't affect how deep the stain is sucked up. On a big house that is a ton of work I would not be willing to do unless very well compensated. My house would never see the sand paper. I think the rough siding has it's own appeal? You got to be the jury also. Do a couple of test spots before you decide. Am I right that the house is not stained or sealed know? Where is the house? Climate different than here in NC could make differences I am not aware of so somebody else might have insights I have not considered.
DADOld Pro, not quite old, not quite pro, but closer every day on both...
I've been waiting for the original poster with the house, schwartz12, to come back online with a post. Where'd he go?
Schwarz12- I saw your thanks message over in business. Glad to see your putting oil stain on there. Should look pretty fine. Best to ya