Pressure treated plywood bench?

[tommag]

When I moved in here there was a nice bench left behind that was topped with green-tinted plywood. I use it for my reloading bench. I have been having brass corrosion problems, even when the brass is in an open container sitting on the bench.
Does anyone know if this is from the treated plywood, or am I just being sloppy with bore cleaners, etc.? The cleaners are stored on a shelf above the bench, but cleaning is done at a seperate bench.
Thanks. Tom

[dubber123]

The plywood may be the problem, as I know in construction, they recommend stainless or coated fasteners when dealing with pressure treated wood to prevent fastener corrosion. Supposedly they are now using a different process to treat the wood, and I don't know if the same fastener specs apply. Try cleaning off the bench and lay a couple thick coats of polyurethane on it to seal it. It'll make cleanup easier too.

[BD]

There are currently three different pressure treatment types approved and on the market as well as the recently removed CCA. To my knowledge all will attack ferrous metals to some extent, some of them severely. I've seen sheets of PT plywood come loose from uncoated nails corroding through on beach front houses in as little as two months. We use stainless and/or copper fastenings and flashings in contact with the new treated wood with no problems with no problems so far, (other than the cost). I don't know about brass, but it could be an issue as the treatment is generally a copper compound. The old stuff, (CCA), was copper arsenate IIRC.
BD

[rugerdude]

A lot of the trated lumber now available uses a MUCH higher salt content. Companies were worried about the toxicity of treated lumber, so they changed the chemicals used for treating. What is funny is that now, treated lumber is only guaranteed for 3-6 months to be free from insect damage. The newer high salt chemicals leech out much faster than the older stuff. But, to answer your question, YES the wood may be causing your problems. Try Dubber's solution and you shouldn't have any more problems. :mrgreen:

[tommag]

Thanks for the advice, guys. I guess it's time to clean off the bench and urethane it.

[1hole]

Tom, you may be less than completely satisfied with painting treated wood. Some of it is badly hydroscobic (SP?) due to the salt content, meaning it attracts moisture. That inhibits paint's, of any kind, adhesion. And it has the potential of causing your steel tools - dies - to rust later if the poly coating should get scratched or flakes off.

I think I would scab on a clean, new top layer of 5/8" particle board, glued, and paint that with the poly. Particle board has a hard, smooth surface that really looks nice under a clear finish. It seems that MinWax Marine Poly is pretty tuff stuff and three coats will seal well enough to prevent damage from gun oils, etc.

[floodgate]

tommag:

There are also some toxicity concerns with treated wood, especially the old copper arsenate; it is at least as nasty as lead residues. I'd either scrap it, or overlay it with a slab of one of the other sheet products mentioned here.

BTW, I followed up on someone's suggestion (thanks, whoever it was!) about the "D-Lead" products offered via Brownells. I got an order of a packet of D-Lead wipes, a couple of de-leading cleaning solutions, and a two-component lead-residue test kit (also works on other toxic heavy metals like arsenic, etc.) for a modest $50.00 in yesterday; haven't had a chance (or maybe I'm too scared?) to check them out yet. Looks like a good set for those concerned with lead residue contamination; check it out on their website.

floodgate

[tommag]

The wife is in town at the fair, so I am on foot. (only one vehicle) I had only about a 1/2 pint of urethane left, so decided to try spar varnish. Boy did that plywood ever soak up the varnish! At the rate I'm using the varnish, it may be cheaper to buy new wood for the top.
After one coat, I'm thinking overlaying with the particle board might be a good idea. I'd hate to tear all my shelves off to pull up the plywood bench, but don't like to throw brass away. It sounds like some of you think an overlay would work. Guess I'll have her stop at the home depot and bring me a sheet of particle board.
Thanks again. Tom

[pumpguy]

tommag, I would probably just use some cheap mahogany underlayment and use that. Coat it with poly and when it gets too ugly or greasy or what ever, just take it off and put on a new one or just cover that one again. Treated lumber is just plain nasty. Try not to get a sliver from it. Guaranteed ***** nasty sore!

[joeb33050]

I'm not a Doctor nor a chemist, but I've worked with pressure treated wood for 32 years and I will never, that's NEVER, have any substantial sized piece of PT wood inside where I'm living. Never.
joe brennan

[tommag]

I went ahead and pulled everything apart and removed the PT wood. The better half brought me a sheet of 29/32" plywood and a sheet of 3/4" MDF particle board.
The nails were severely rusted where they went through the PT plywood. Looks like it was a good thing to get rid of! Hopefully my corrosion problems are a thing of the past.
Now I'm just waiting for the polyurethane to dry and put on another couple of coats.
Thanks for the advice, guys!
Tom