Use A Water Based Primer On PMF Before Final Paint Color?

[Jwh92020]

My local Hd & Lowe's stores very seldom have "oops" paint. Can I use something like Kilz 2 for the base coats on the raw PMF before applying the final top coats?

 

[Pmullen503]

Yes (I'm assuming you've attached attached the canvas with some form of adhesive.)

 

[Jwh92020]

I'll be using Titebond 2. I see some people say to water the glue the glue down, others don't. Watering it down seems that it would reduce the holding power. As for using Kilz - full strength or watered down? I'veeen people using a 50/50 water-pInt mixture, then 75/25, then full paint for the topcoats. I'm thinking a full strength coat of Kilz, sand, another coat of Kilz, sand, paint, sand, paint again. I found 10 oz cotton duck cloth in 60" width for $4.50/yard. $77.00 for enough to cover the trailer shipped to my door. No dealing with drop cloth seams. I figure I'll roll it on to a carpet tube, hang the tube from saw horses and take off what I need as needed.

 

[Pmullen503]

Here's what I did: Cut a piece about 6" wider than the area you want to cover, tape the edge to a piece of plastic pipe and roll it up. Put a piece of rope through the pipe such that you can suspend it where you need it.

I worked in about two foot sections. Roll on your glue (don't thin more than 5-10% with water) to the trailer. I rolled glue on the back side of the canvas (again about 2'), then roll a second coat of glue onto the trailer. Roll on the canvas. I pressed it down with the roller. Then using a scraper (the plastic kind you would use for bondo) press the canvas on to the trailer squeezing out any liquid glue or air bubbles. That step is important. You want good contact and no air bubbles or liquid glue. You really can't sand the canvas so get it smooth. Worst case poke some holes in a bubble and work it down while the glue is still wet. Proceed in 2' section until you are done.

The outer side of the canvas is still almost dry at this stage. Once you complete the area you are working on, you can roll a nice wet coat of glue onto the outside of the canvas and scrape again to make sure it's down and smooth. After the glue dries, trim any excess then you can proceed with coats of paint. That first coat with require A LOT of paint, subsequent coats much less.

Canvas can't go around a sharp corner. 3/4" radius is about the minimum for 10 oz cloth. You can trim over laps (2-4") with a SHARP utility knife at the stage where the glue isn't wet but not fully cured. Make several light cuts and try not to cut the layer below.

 

[Jwh92020]

Thanks for the tips. If I'm going to put trim on all the corners, can I trim the fabric flush at each edge, rather than wrapping it around? Also, I've seen where people use a 50/50 mix of paint & water as the first coat after gluing, rather than a second coat of glue. After it dries, they sand to knock off the "fuzzies". Then they roll on a coat of 75/25 paint and water, sand again and begin the top coat process, where they sand between coats as well. In my case, if my local big box doesn't have "oops" paint, I would use Kilz as the first 2 coats.

 

[Pmullen503]

Is this a foamie or wood? Foamies work because the canvas forms a continuous tension "sock" to keep the foam edges together. Even if it's wood I would still fiberglass and epoxy the corners and then then cover the wood with PMF.

If you are careful and use something like Sikaflex to bed the trim you should be okay. The corner trim is a place where water can get it and start to rot.

I would never thin latex paint more than 5 or 10%, it won't polymerize properly and even 5% water really thins out latex. The canvas will absorb plenty of paint.

What you may be thinking of is "The Mix" for sealing wood (especially end grain plywood) with oil based polyurethane. A 50/50 poly/ thinner mix to soak the wood, let it dry, come back with 75/25 poly/thinner and then a final coat of full strength poly.

 

[Jwh92020]

I'm building with wood. The videos I saw were people who tinned latex tp 50/50 for the first "primer" coat, then 75/25 for the second. After that, they put on full strength in whatever color the were using for the finish coat. Usually it was 2 - 3 coats. One was a foamie, the others were wood. Your point about the possibility of water getting in around the trim is well taken. Have you heard of anyone using bed sheets instead of canvas? I saw a video today where a guy used them and his finish was much smoother than any other PMF I've seen.