Any idea how to remove "thick" films from a redwood deck?
They are dark (almost black) and I'm pretty sure they are aged films of the Thompson water seal. At manufacturer's suggestion, I tried a stripper which only discolored the parts of the deck that were nearly bare but did nothing to the film.
The film is thick enough in places that it mucks up sandpaper fairly quickly and adherent enough that scraping w/ putty knife & screwdriver is slow going. Oxalic acid removed the discoloration caused by the stripper but did nothing significant to the film.
How to remove Thompson water seal
Chemical stripper followed by powerwashing. 2500 PSI or a little more with a wide spray wand so you don't gouge the wood. Be aware you may not be able to remove it all if it is old. Wood, as an organic material, will absorb coatings and it is almost impossible to get them all off. The best thing to do is to get the deck cleaned as evenly as possible, and then use another product with a tint. You do not want to leave any untreated wood on your deck or it will deteriorate faster than your wallet will like.
I used to really like Benjamin Moore coatings, but the last few times with our large deck I've used the Behr deck product and have been very pleased with its durability and application.
HTH and good luck.
I used to really like Benjamin Moore coatings, but the last few times with our large deck I've used the Behr deck product and have been very pleased with its durability and application.
HTH and good luck.
My past experiences with Thompson's would suggest that just waiting for six or so months after application should be enough for the seal to degrade and go away on its own. I wonder if this is really Thompson's, or something better?
Regardless, I would look into pressure washing, perhaps in combination with a chemical stripper.
Regardless, I would look into pressure washing, perhaps in combination with a chemical stripper.
Powerwashing. However, it would probably take a couple of years to do it right. I have mine done by a pro who got my 15 year old deck looking brand new. It took about 4 years to get it to this point.
The guy who treats my deck hates Thompson products and uses something that is very expensive. The name escapes me right now. Whatever he is doing is working great.
I now only have it done once every other year.
The guy who treats my deck hates Thompson products and uses something that is very expensive. The name escapes me right now. Whatever he is doing is working great.
I now only have it done once every other year.
Let it weather
I second exigent's comments. I've found that fully exposed WaterSeal doesn't last any longer than the label promises. Your problem is something else.
Thanks, all, for the responses. I suspect my problem is a result of cumulative actions over the years. Initially we had some sort of stain as a protective coating. In one year, the stain blackened badly so I removed it and started using the Thompson's water seal instead. At some point (don't remember the exact sequence), a high pressure water washer was used (and abused) resulting in some uneven surfaces and also some deep grooving. I also started applying the water seal annually which may have resulted in thicker than desired coatings.
Although pressure washing removed much of the coating, the residue consists of a thick hard brittle film which can be removed with some difficulty w/ scraping w/ screwdriver tip or putty knife and a thicker rubbery film which is somewhat harder to remove. While it is possible that further pressure washing could remove these, I confess to be a bit "gun-shy" because of the previous event and the surface irregularities
present because of the previous damage.
I had a question about how strippers work.......do they depend
on having a thin film present and work by dissolving from the surface down? or do they work by undercutting from the edges of the film/deck bond? If it is the former, then a stripper might have trouble w/ a thick film?
Although pressure washing removed much of the coating, the residue consists of a thick hard brittle film which can be removed with some difficulty w/ scraping w/ screwdriver tip or putty knife and a thicker rubbery film which is somewhat harder to remove. While it is possible that further pressure washing could remove these, I confess to be a bit "gun-shy" because of the previous event and the surface irregularities
present because of the previous damage.
I had a question about how strippers work.......do they depend
on having a thin film present and work by dissolving from the surface down? or do they work by undercutting from the edges of the film/deck bond? If it is the former, then a stripper might have trouble w/ a thick film?