Teardrops n Tiny Travel Trailers

My floor is starting to come together and I'm wondering if I should apply "The Mixture" (poly and thinner) to the inner surfaces before gluing the foam in place. For that matter, should I seal the "back" (outside) of the inner wall skins before gluing them to the wall frame and foam?

Will the sealed surfaces take the spray adhesive and TB2 needed to make the structural bond, or should I not bother with the mixture and just let the spray adhesive and exterior treatments (canvas edge wrap and tar undercoat) protect the inside cavities of the floor?

Also, when using the mixture, what do you do if you want a stained wood finish? Stain first then seal with the mixture, or just stain and use full strength poly over?

I'm thinking that using the mixture first would interfere with the stain and/or wood glue application.

I've read the arguments for sealing the backs of everything, but it seems like a lot of work if it isn't really going to make that big of a difference, or if it will hurt on bond strength.

If I need to leave areas untreated where the glue goes, and I use masking tape to do that, will the mixture wick under the masking tape enough to adversely affect the glue bond?

Thoughts?

My inclination is to build out the floor with just the glue and adhesive, mask the areas where the walls and bulkhead will attach, then treat all of the remaining outer surfaces and edges with the mixture.

There was some speculation a while back that the heavy ratio of thinner could actually damage the plywood by breaking down the glue layers in the plys, but I can't remember if that applied to WBP ply glues, or just interior grades.

this is what i was told by gpw when doing my floors. where ever the foam to wood would be, leave it alone. you need the bonding area clean to make it stick. i know i just paraphrased it, but you could seal other areas, just leave the bonding areas alone.

but i will wait now for the experts to chime in.

Although not being an expert , I agree with Eagle ... The mix should be applied after the pieces are glued together ... The wood to wood or wood to foam bond should be done on the bare product ... You could mix stain in with the mixture , many poly stains are just that ..
As far as the solvent being non compatible with a plywood product ... I don’t know ... All my efforts were quite successful... Logically , you should try it out on a piece of scrap First...
Inner skins should be waterproofed by the glue used to secure it ... depending of course on the glue used ... T2 works on a wood to foam bond , even though it takes longer to dry as the wood absorbs the moisture allowing the glue to dry ... I’ve done many balsa to foam laminations with much success (T2) allowing a couple days drying time ...
Paints , fillers , all seem compatible over cured T2 ... No problems ... If I have a smooth surface in doubt , I give it a light sanding first to increase the “tooth” ... then paint .

The 30NF is a waterproof neoprene glue so it already gives you waterproofing on the inside.