poormans fiberglass overfoam prime or no

[ghcoe]

most primers work for my needs, which is not gluing canvas to foam, but priming foam for TBII and canvas for paint.

Does that mean primer goes between the foam and TB2?

I have built my trailers both ways. #1 I primed the whole body first and then covered with canvas. #2 I decided I would try to save time and money and opted to apply canvas over bare foam. I have not found any delamination on #1, but have had to repair some delamination on #2. To be fair though I do use #2 pretty hard and there was some construction issues that did cause some delamination that are fixed now. Still though I do believe there is a stronger bond in the long run using primer first and then TBII.

[John61CT]

Interesting.

For me the ideal would be primer as waterproof sealant + adhesive too, so only three structural materials total involved.

Outermost paint just for cosmetic + UV protection.

[ghcoe]

Interesting.

For me the ideal would be primer as waterproof sealant + adhesive too, so only three structural materials total involved.

Outermost paint just for cosmetic + UV protection.

Primer is usually not waterproof. It is more like a real water down filler like spackle. It is porous so paint will bond to it well.

I find the 50/50 mixed TBII penetrates the canvas well on both sides so you don't have to worry about canvas rot. Also, this wets out the canvas and allows it to relax and lay flat. I don't preshrink my canvas so with wetting it out and with the natural shrinking I can get a nice smooth finish. Something that I think would be hard to do with applying canvas with paint/primer.

[John61CT]

Yes an extraordinary primer is what's needed.

And maybe the new Gripper's fine. . .

[GPW]

Now the only problem we had with TB2 ( well painted over) was the continuous wetting underneath by the “ morning dew” that ran down the sides and the under the floor , eventually weakened the TB2 causing it to decompose and allowing the canvas to rot ... George’s drip edges solved that problem !!! So basically if it doesn’t get wet every day , you’ll be fine with TB2 , if it does ( like here) best build it like a boat ( or just use drip edges) … or some type of gripper-like primer … We tested the old Gripper when we cut that “trolley top” off the FS , the Gripper was used as the new canvas adhesive, and sat out in the weather for several months bare before we had a chance to paint it … A quick wash , a couple coats of paint and it's been Fine since … I’ve long been a TB fan/user but a Good primer just makes it so much better … JMHO

[ghcoe]

Funny we should be talking about primer and then I was in need of primer today for #3. I was just going to purchase some generic low cost primer, but I saw some Valspar Bonding primer https://www.lowes.com/pd/Valspar-Interi ... 1000381269. What caught my eye was it mentioned good for coating over glass and ceramic. I remembered that Gripper also mentioned it was good for coating glass. Well it cost a bit more, about $5.00 per gallon, but I though I would try it. So my first impression is that I think it is better than Gripper. Poured out more like pancake batter! I was thinking it was going to take a lot to coat the sides and roof of #3, but it only took 1/4 of a gallon! I mean covered. No pink showing. So it cost a bit more, but I think it goes twice as far for coating saving money in the long run.

[John61CT]

Sounds good! Was that the two part stuff with hardener?

Sure you know, but by default make sure to use PPE by default tons of ventilation, the best stuff is nasty dangerous

[GPW]

Great find George !!! That looks good (specs ) !!! Hope it lives up to expectations ...

[ghcoe]

Sounds good! Was that the two part stuff with hardener?

Sure you know, but by default make sure to use PPE by default tons of ventilation, the best stuff is nasty dangerous

It is one part. I don't like messing with two part stuff.

[JazzVinyl]

Funny we should be talking about primer and then I was in need of primer today for #3. I was just going to purchase some generic low cost primer, but I saw some Valspar Bonding primer https://www.lowes.com/pd/Valspar-Interi ... 1000381269. What caught my eye was it mentioned good for coating over glass and ceramic. I remembered that Gripper also mentioned it was good for coating glass. Well it cost a bit more, about $5.00 per gallon, but I though I would try it. So my first impression is that I think it is better than Gripper. Poured out more like pancake batter! I was thinking it was going to take a lot to coat the sides and roof of #3, but it only took 1/4 of a gallon! I mean covered. No pink showing. So it cost a bit more, but I think it goes twice as far for coating saving money in the long run.

Here is a question, if one uses a non gripper (or whatever product that would be a good replacement) primer, what consequences could they expect from using 'just any old primer'?

[ghcoe]

Here is a question, if one uses a non gripper (or whatever product that would be a good replacement) primer, what consequences could they expect from using 'just any old primer'?

Probably nothing. I was just going to use generic primer before I found the Valspar.

if you are going to use it for a canvas to foam glue it might make a difference. Or it might provide a bit extra protection from delamination or not. The test is out.

[John61CT]

Worst case the canvas delaminates from the foam and the whole structure falls apart.

Second worst, the outer paint coats delaminate from the canvas/adhesive layers.

[ghcoe]

Worst case the canvas delaminates from the foam and the whole structure falls apart.

Second worst, the outer paint coats delaminate from the canvas/adhesive layers.

If you glued the canvas together at the edges this wont happen. worst case is you need a syringe to inject some 50/50 TBII between the canvas and foam and reattach.

[John61CT]

Worst case the whole thing collapses catastrophically upon exiting a tunnel high in the mountains 8-)

Yes worst cases are unlikely. . .

[GPW]

We used TB2 , Gripper both on the FoamStream . 7 Years now sitting Outside …The only thing that’s falling apart is the Owner …