Posted by Sherman in Idaho [24.32.202.166] on Tuesday, October 01, 2013 at 19:44:35 :
In Reply to: O/T- steam cleaning a log house posted by junkyardog [72.64.5.243] on Tuesday, October 01, 2013 at 18:40:41 :
I've never heard of steam-cleaning wood. There's probably a reason. Pressure washers work okay if the wood is sound, the paint is loose, and you use a fan-type nozzle and hold it at a low angle to the wood. If you're not careful, you'll blow a hole right through cedar shingles and lap siding before you even knew what happened. A lot of people do a cheap job of painting a house by using nothing but a pressure washer for the prep, and the results show it. Even if you're careful and you don't damage the wood too much, you'll have to let it dry for a week of good hot weather before you can prime it with oil primer or stain and expect it to penetrate and last.
Chemicals are tedious and expensive. The "safe" kinds (alcohol and lye, basically) won't take off anything except latex paint, and the good stuff (methylene chloride and lye) costs a lot, makes a mess. will burn your skin, will knock you out if you breath much of the fumes, and will probably kill your bushes if it gets on them.
Sandpaper gets clogged too fast, and any sort of grider/flap disks are expensive, tear up the wood, and get clogged too fast.
I've tried all the shortcuts, and the best method is still scraping by hand with a paint scraper. To remove well-stuck old oil paint, an electric heat gun (or blowtorch if you're careful) combined with s scraper is your best bet. At least you're outdoors where the fumes and smoke aren't a problem.
Ideally, for the best job with the least work, you'll pressure wash first, carefully, to get the loose stuff, moss, bugs, etc off, being careful not to chew up the wood. Then you'll scrap whatever still needs to come off with a hand scraper, perhaps assisted with heat. Then if there's much dusty residue left, you'll pressure-wash it again lightly to get all that off. Then let it dry for a week of hot weather, and then prime or stain with something oil-based.
Just like with painting a car, most of the time involved in a good house painting job is prep.
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