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Yet Another PMF Question

PostPosted: Sun Aug 20, 2017 11:06 pm
by mjcook
I'm in the middle of building my tiny trailer; 5'x8'x4'. It's a foamie with 1/8 ply interior and PMF for the outside. In another week or so I'll be ready to start laying the canvas, but this is my first trailer build and I'm not entirely confident in what I'm doing yet...

The question is...
(drumroll please)

How much paint/glue will I need for the outside?

Ok, I know that there's a lot of variables that go into calculating that; I've learned that much from all the fantastic treads on this forum. But in all my digging I can't find a definitive answer so I'll ask outright, and perhaps we can create some sort of table or something to help those who come after us.

Based on people's experiences, what can be expected in terms of gallons per sq/ft for the various common weights of cloth, (say 6oz to 12oz) depending on what technique and medium is used? (Gripper, TBII, Exterior paint, etc.)

Oh yeah, and if you're curious: I have your generic 12oz duck cloth canvas, and the approximate coverage of the exterior of my trailer is 124 sq/ft. My foamy uses 1" white EPS foam, so as I understand it TBII isn't an option. I'm using Gripper for the adhesion of the foam to foam (to make 2") and foam to plywood. I'm painting both sides before laminating, and I think I'll finish off my 5 gallon bucket of Gripper with the wall construction. If I do, then 5 gallons of Gripper goes about 736 sq/ft, coming to almost 150 sq/ft of one-coat coverage for 1 gallon of Gripper. I'd say that means I'll need at least another 5 gallons of Gripper to get a good thick PMF... Am I right?

Re: Yet Another PMF Question

PostPosted: Mon Aug 21, 2017 9:01 pm
by pchast
Gripper is an interior product. I used gripper to adhere the canvas and do a first coat
after it dried on. Then I followed with 2 coats of Exterior house paint(latex). Its been
a few years and 5 or 6 trips. I found no problems When I washed it recently?

Re: Yet Another PMF Question

PostPosted: Fri Sep 01, 2017 11:44 am
by mjcook
Thanks for the reply pchast!
I wish a few more people would add their $0.02, I was thinking this thread would be helpful for more people than just me.
Anyways I'll probably do as you did, and hope for the best. :thumbsup:

Re: Yet Another PMF Question

PostPosted: Fri Sep 01, 2017 2:44 pm
by dancam
If your trying to calculate it for yourself you could skim my build thread. I believe i wrote down how much tb2 and paint i used. Was about 596 square feet of pmf Total for inner and outer halves of my trailer. 100sq ft was over plywood, the other 500 over foam.

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Re: Yet Another PMF Question

PostPosted: Wed Sep 06, 2017 12:00 am
by mjcook
Thanks. I skimmed your build and I noticed that you went through more paint than you were expecting; I've already started skinning my build and I am experiencing the same thing. More than 2 gallons of gripper sucked up by 120-ish sq-ft of canvas, and I haven't even started sizing yet! :shock:

Oh and one other unimportant thing, I think I ended up with 6oz cloth, not 12oz like I stated above. 6oz is significantly thinner, right? Because this stuff seems pretty thick to me...

Re: Yet Another PMF Question

PostPosted: Wed Sep 06, 2017 9:39 am
by dancam
mjcook wrote:Thanks. I skimmed your build and I noticed that you went through more paint than you were expecting; I've already started skinning my build and I am experiencing the same thing. More than 2 gallons of gripper sucked up by 120-ish sq-ft of canvas, and I haven't even started sizing yet! :shock:

Oh and one other unimportant thing, I think I ended up with 6oz cloth, not 12oz like I stated above. 6oz is significantly thinner, right? Because this stuff seems pretty thick to me...


Yup, it takes a ton of paint.
I believe i used, 8oz cloth and its fairly heavy duty. Not sure what you were expecting so i cant say weather you have 6oz or not, but yes, 6oz is very much thinner than 12oz



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Re: Yet Another PMF Question

PostPosted: Wed Sep 13, 2017 1:28 pm
by mjcook
Well I finished the canvas, and it took 5 gallons of paint total; from start to finish.
2 gallons of Gripper primer to adhere the canvas
2 gallons of PVA primer to size the canvas
1 gallon of top coat exterior paint

And I can still see the texture of the weave through the paint.
151072

This works out to roughly 1 gallon of paint to finish less than 25 sq/ft of 6oz canvas.
The moral of the story is as dancam says: PMF takes a TON of paint.

Re: Yet Another PMF Question

PostPosted: Wed Sep 13, 2017 1:37 pm
by dancam
mjcook wrote:Well I finished the canvas, and it took 5 gallons of paint total; from start to finish.
2 gallons of Gripper primer to adhere the canvas
2 gallons of PVA primer to size the canvas
1 gallon of top coat exterior paint

And I can still see the texture of the weave through the paint.
151072

This works out to roughly 1 gallon of paint to finish less than 25 sq/ft of 6oz canvas.
The moral of the story is as dancam says: PMF takes a TON of paint.


Yeah, i tried to keep rolling more coats on till the outside was pretty smooth on mine. Then the water evaporated out of the paint and you could still see the weave.... but it just seemed like i was constantly buying paint. When you run your hand on your paint does it feel smooth or a bit rough? Image

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Re: Yet Another PMF Question

PostPosted: Fri Sep 15, 2017 10:55 am
by Tigris99
Paint itself is mostly liquid that evaporates over time. There are a few ways ive read about to increase the solids content of the paint to help fill the weave better. Chalk, light weight spackle, latex caulk, each or combination of mixed into the paint.

And the more time goes on the more the weave will show till all the paint full cures. Best to let is cure for a few weeks before adding paint again.

Also read that using a squeegee when doing weave fill finishing helps A LOT as simply rolling it on still leaves a texture, even on a smooth surface.

Stuff im probably going to try before winter as i want to put another heavy coat on before it gets cold.

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Re: Yet Another PMF Question

PostPosted: Fri Sep 15, 2017 1:41 pm
by John61CT
Are their disadvantages other than cost to using very fine weave canvas?

Re: Yet Another PMF Question

PostPosted: Fri Sep 15, 2017 1:49 pm
by dancam
Do you have a link to one for sale?
(I didnt realize fine weave canvass was a thing)
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Re: Yet Another PMF Question

PostPosted: Fri Sep 15, 2017 2:11 pm
by John61CT
Army duck maybe.

But could be Egyptian 800 thread count sheeting, just asking in general.

Re: Yet Another PMF Question

PostPosted: Fri Sep 15, 2017 9:49 pm
by mjcook
dancam wrote:Yeah, i tried to keep rolling more coats on till the outside was pretty smooth on mine. Then the water evaporated out of the paint and you could still see the weave.... but it just seemed like i was constantly buying paint. When you run your hand on your paint does it feel smooth or a bit rough? Image

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My canvas is smooth, albeit textured. When I put the first coat of primer on to size the canvas, there was a rough texture on the surface. I knocked it smooth with a (very) quick pass of a sander using 220 grit, after that, every layer went on and felt smooth.

I guess I'm content with how filled the canvas is, providing it is filled enough. I'm certain that there are no voids where the canvas is still exposed; the entire surface has paint in/on it and there are no holes through the canvas that are visible (like that means anything). So will that be good enough?
:thinking: