Do you seal before you skin?

[NathanL]

Nothing will rot away wood faster than having a tarp, especially a plastic tarp laying right down on top of it. If you must cover with a tarp make sure to put some stickers under it to allow for ventilation at a minimum.

Even on this board there has been several people who covered their in progress project with a tarp only to discover later it was worse than leaving it uncovered because it trapped the moisture against the wood.

[jdarkoregon]

I sealed mine before skinning it, I figured it would be cheap and surly wouldn't hurt anything. If you are planning to keep it outside, I would strongly suggest you seal it.

John

[S. Heisley]

I've never used a skin. (Mine is coated with CPES/Epoxy primer/Polyurethane boat paint.) But, if I were to skin mine, I would probably put some sort of seal on the wood first. Think about what would happen if, for some reason, the skin leaked; or, if water got on it before you got it skinned.

You don't tell what kind of plywood you are using. I'm guessing it is the standard stuff that most of us purchase and not marine grade. Please be aware that on bare plywood, delamination can begin to happen in less than 10 minutes. Got a scrap of bare plywood that you don't need? Lay a damp paper towel on it for 10 minutes or over night and then take it off. Watch what happens.

[S. Heisley]

I'm using exterior grade ply, same as marine grade. It takes a beating, I've used lots in construction but never on any angles like this.

I would still test a scrap, to be on the safe side. Wet a towel, wring it out, and lay it on it over night. Take it off the next morning and wait a day to see what it does. Your teardrop is looking beautiful; and, if I were you, I wouldn't want to take any chance of messing up all your hard work.

Also, about that tarp, I've seen pictures of mildew in the pattern of the tarp's weave, on teardrops, wherever the tarp touched the roof. Please be careful. If you are going to leave that tarp on, ensure you have excellent air flow underneath.

Only you can decide what you think is best to do.

[aggie79]

I sealed my plywood with epoxy before I applied the aluminum. My aluminum, though, is floated rather than glued.

I've heard of others that have used a thinned varnish as a seal coat. If you did this, you could do a light sanding before applying the contact cement for the skins.

[Woodbutcher]

I used latex enamel that I had left from another project. I spent to much time and money on my trailer to take what I believed was a short cut by not sealing it. I too floated my aluminum. Also I used a window seal tape on all joints before covering with the aluminum. Good luck finishing your trailer.

[webbaldo]

Here in the UK there is a product called G4 Damp Seal, its what they also use to paint on concrete for ponds (pond sealer). I was gonna use epoxy but this stuff was miles cheaper and several UK TD builders swear by it.

[Oldragbaggers]

The vinyl may be waterproof, although I wouldn't bet the farm that it is "totally" waterproof. But at any rate, all it would take is the smallest pinhole size puncture or tear from road debris or a tree limb or whatever and you would have an ingress point for water. If your plywood is unsealed at that point it becomes totally vulnerable and any moisture that makes its way under the vinyl will remain under the vinyl and work on delaminating your wood. In short, I wouldn't even dream of not sealing it.

[Oldragbaggers]

Interesting. I stand corrected. I was thinking more of a marine or automotive vinyl. You're talking about a horse of a different color.

Although epoxy doesn't "react" with contact cement. Once epoxy has cured it pretty much doesn't react with anything. Talk about bullet proof!! I have used contact cement (the spray on type) to adhere carpeting and vinyl to the interior walls of fiberglass boats (standard practice in the industry), have never had a problem and have never had an issue with them remaining stuck, even in that moist environment. I can't foresee any problem with sealing with epoxy under contact cement.