Fixin to get ready

Canvas covered foamies (Thrifty Alternatives...)

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Re: Fixin to get ready

Postby LostCajun » Tue Oct 16, 2018 12:25 pm

John61CT wrote:So, to summarize my current stage of thinking, logical sequence rather than chronological:

A) Adhesion prep:
1. Rough up the foam, sand the surface, get holes in it (spiked roller, dance on it with golf shoes?)
Blow off the loose kruft (power wash, let dry?)
2. First layer, full strength Glidden Gripper, push into roughed-up surface with bondo scraper
(Let cure? or proceed with skinning?)

B) Structural skinning:
1. Prep canvas pre GG, (prewash, preshrink) cut w/ generous edge excess
2. Heavily coat foam, flats and edges / joints / corners and soak canvas (roller / brush / both?) in full strength GG
3. Lay down canvas, ensuring 100% saturation no bubbles and flatitude (? roller / scraper / brush / all?)
4. Do edges / joints / corners as you go, cutting angles, trimming overlap (no idea handwaving here) then saturating in full strength GG
5. (not drying time between coats? tack?)
Add as-little-diluted-as-possible GG initial coats, then full strength to the canvas until certain all weave is well filled in
6. Repeat full strength coats to build up / smooth surface (? drying time between?)

C. outermost finish / skin
(? maybe micro bubbles / fairing compound if super-smooth outside finish desired?)
paint, gel-coat, aluminum sheet, whatever outside
maybe luan, birch ply paneling, beaded hardboard whatever indoors



I am trying to figure out what I will do with this also...

I believe that after blowing the dust off I would add a step of 91% alcohol wash of surface before any adhesive (from what I have read...not tested any of this yet....working on my level table now)

Craig
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Re: Fixin to get ready

Postby GPW » Tue Oct 16, 2018 4:38 pm

1. the “holy" thing is optional … but you may want to rough sand the foam to break the gloss … Vacuum that off , wipe with alcohol to get rid of “finger grease” Then apply the canvas making sure you have generous glue coverage on BOTH surfaces ( like hanging wallpaper )
2. ( see #3 )
4. Yes
5. I let them dry for at least a few hours before recoating … The thinned binder ( glue ) is not to fill the weave but to really get in there and encapsulate every fiber of the covering in waterproof plastic … The primer fills the weave , if you really need that … Better than that is Artists thick gesso applied with a Bondo spreader which really makes the surface Flat ...
6. make sure you have a good smooth primer coat and then apply 2 coats of a GOOD Exterior Latex enamel … Which can be Oops paint as long as it's Good quality … Let dry/cure for 3-=2 weeks before scrubbing it … living outside , ours needs a good washing about twice a year … spic and span , diluted bleach on the tough spots ( mold ) … when the paint gets chalky , just give it a fresh coat …
Hint: if you put some saran wrap inside the paint can making an airtight film across the unused paint , it will last for years or until you need it again ... ;)
7.. Relax and enjoy your Cool new trailer ... :beer:


*** The above is just the way we do it …. many ways to choose from , pick what’s best for you , test anything you don’t believe... :thumbsup:
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Re: Fixin to get ready

Postby ghcoe » Tue Oct 16, 2018 5:23 pm

I have applied the canvas two ways now. Once with Glidden Gripper applied first to the foam and then canvas using a 50/50 mix of TBII. The second time I just applied the canvas to the foam with a 50/50 mix of TBII.

I have had no delamination problems with the TBII over GG.

I have had some delamination issues with the 50/50 TBII over foam. In saying that I will have to admit to a couple of possible issues that may have cause the delamination issues and not the technique. I had two bubbles appear on the rear bottom right corner. Easy fixes, but thinking back I do remember that area freezing before fully curing. Second delamination appeared after installing supports to lift the body up off the frame for a drip edge. After the next trip I found delamination directly above the supports. I had designed this trailer a bit different than my last trailer and did not install what I call interior frame rails. My thinking was that the body was supported in only 5 locations and it applied too much stresses in this area. I installed interior frame rails to spread the load out more across the floor and the next trip I had no delamination issues at all.

Delamination is not really a big deal. I fixed all my delamination issues in about 1/2 hour.

I think most people overthink this applying canvas part of the foamie build. There really is no outward force on the skin to create a problem. Very little tack is needed to keep the canvas attached to the foam. I would much rather have a canvas cover that is easy to pull back if needed for repairs which would also be easily glued back. If you have a canvas that chunks out the foam when pulled back you then have to resurface the foam and replace the canvas to get it to lay back down flat.

Also, I apply Harbor Freight canvas out of the bag. I use the shrinking of the canvas to help "pull" out the wrinkles and make a drum tight skin, which also aids in keeping the canvas stuck to the surface.

DSCF4249.JPG
Canvas
DSCF4249.JPG (139.68 KiB) Viewed 673 times


I do think perforations at the wall glue points can help a lot in glue joint strength though.

These are just my observations. I will have some videos up sometime this winter on how I canvas my #3 trailer to help people out on how to make their own foamie.
George.

Gorrilla Glue, Great Stuff and Gripper. The three G's of foamie construction.

My build viewtopic.php?t=54099
Working with flashing for foamie construction viewtopic.php?f=55&t=60303
Making a hot wire http://tnttt.com/viewtopic.php?f=55&t=55323
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Re: Fixin to get ready

Postby John61CT » Tue Oct 16, 2018 8:01 pm

I've understood the sand / clean the foam to be useful because the makers use a slippy "release agent" that's left on the finished product if you don't, can reduce adhesion
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Re: Fixin to get ready

Postby Postal_Dave » Wed Oct 17, 2018 10:29 am

The holes add little anchor points. By putting the glue or gripper in that first and allowing it to dry, the attachment coat has something better to cling to.

Here is an easy experiment I did. I put down a piece of wax paper. I put a drop of TBII on it (about the size of a nickle) and let it dry for a few days. Then I put another drop of TBII, beside the first drop of glue but with a 25% overlap and allowed that to dry for a few days.

The dried glue pealed off the wax paper easily. Then I tried to pull the two drops of glue apart. They would not separate. When the glue did break apart, it was Not at the seam where the two drops met. Glue sticks to glue Very well.

Dave
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