Wood Preservative and Water Sealer: Same Thing?

[chorizon]

I'm getting ready to buy the materials on my BOM for the floor. On the list is Wood Preservative. Will this stuff work as well?:

http://www.lowes.com/lowes/lkn?action=productDetail&productId=194507-86-79030A/01&lpage=none

I'm using exterior grade plywood for the floor and sides. The tag says it is good for outdoor use if "sealed properly". I'm also a little concerned about formaldehyde used in some preservatives, as some of the posters here have pointed out that its "bad for you".

What to do? Hmm...

[Trackstriper]

Looked at your album. Nice start. I can't address the issues of the exterior exposure and sealing the outside of the tear.

Formaldehyde out-gassing is not good for anyone, but people have different tolerances. I'm one of those who are especially sensitive. My trailer build will be substantially complicated because of that. It will probably be primarily aluminum.

It looks like you used a five-ply panel which is probably good. The exterior plywood typically off-gases much less than interior ply, maybe by a factor of 10-15 to one. I would think that the number of plies also factors in as you have many less glue lines than if the wood had many more plies, as some interior grade cabinet wood. I don't know if the cabinet grade plywood (or best of what you can find at Home Depot, like their birch or oak veneer) is available with exterior glue. I would assume that it's interior grade glue, and an import at that, where quality control and emission issues are more lax. I think you did well with the plywood you got.

I don't think that a coating containing formaldehyde as a paint product preservative would give you much of any kind of problem on the exterior of the body. It's not likely to have much in there anyway and its on the outside of the plywood where it can vent to the great outdoors. The problem is excess formaldehyde used in the urea-formaldehyde glue that doesn't react when the glue sets. This excess reacts with moisture and causes the out-gassing. Exterior plywoods typically use phenol-formaldehyde glues which don't exhibit as much of a problem.

There is a paint/coatings company that specializes in products for sensitive people. They make low VOC coatings that are also designed to block formaldehyde transmission through the coating, by a factor of 90-95%. You can't stop it all, but you can slow it down to where there is not much of a problem with reasonable ventilation. I spoke with one of their reps last week and he recommended their Polyureseal product as the best for wear and tear and as a gas sealer. Basically a waterborne poly that's designed for a special purpose. Maybe a similar coating would work just as well, but this stuff is not that expensive if you think you could be sensitive.

http://www.afmsafecoat.com/

My wife and I get the same symptoms, which are rather typical, when we get a dose of formaldehyde: watery eyes, shortness of breath (like asthma), brain gets a little foggy, possible headache. Just going to our Sunday school class can wipe Suzan out for a day just because of the formaldehyde in the women's "perfume", and the ingredient toluene doesn't help either. No energy, linked to fibromyalgia and chemical sensitivity syndrome. We're a mess. Most folks don't have to experience this and standard teardrop construction isn't a problem. But that said, if it took me an extra ten-fifteen bucks to coat the inside walls of a very small enclosure to reduce this off-gassing, I think it would be worth every penny.

Just my two cents worth.

If you don't mind me asking, what kind of $$ did it take to get the sides cut by laser?

J.B.

[chorizon]

Thanks a lot! Fortunately, I work at a precision sheetmetal and machining company, and didn't have to pay anything. But, the laser blew threw these parts in about 5 minutes. The operator took about an hour total to set the machine up and run the parts. That being said, these pieces should fall under any sheetmetal shop's "shop minimum". Ours is $150, and I think thats pretty standard.
For me, with marginal woodworking abilities, I think thats a bargain. Not only did it save me a lot of time, but all the pieces are identical. I was able to draw the parts in CAD myself, so I knew exactly what I was getting. I'll post my .dxfs on the CAD forum once I've proved the parts out, to make sure they fit like I thought they would! That way, anybody who wants to can take the .dxfs to a sheetmetal fabricator, and they'll be able to create a laser program from them to cut the parts out.