PMF over wood questions

Finishes, paints and coatings

PMF over wood questions

Postby lacofdfireman » Tue Mar 12, 2019 11:31 pm

So as some of you may have seen I’ve had a tough learning experience with my Overland style Teardrop trailer I built. Long story short I took some bad advice and used a Raptor Liner spray on material over untreated 1/4” Baltic Birch plywood with terrible results after 4-6 months. It was rock hard and with wet weather the wood expanded and contracted causing my wood to delaminate and start stress lines and eventually peeling of the outer layer of the wood.

Image


You could actually peel the entire first layer of wood off in big strips.


Image

So I decided to remove the entire outer skin and will be reskinning with 1/4” Baltic Birch again tomorrow.

This time I want to do it right and not have to go though this again. I’m super interested in using the PMF method for the outer skin but have questions. Most of the threads I seem to be reading they are using PMF on foamie trailer so I want to learn if this is a good option for wood trailers and the best method for applying it.

1. Do I need to pretreat the exterior wood before doing PMF? I’ve watched a few YouTube videos and they seem to just do it straight to the wood. No pretreatment. If pretreatment what’s the best method?

2. For wood is it better to use Titebond 2 glue or Paint? I already have some PPG Gripper paint if that’s a valid option. Just not sure if it’s as good as glue.
Also if glue or paint do you do a layer of glue or paint on the wood first then lay the fabric on the glue or do you just hold the fabric up to the trailer and glue the fabric to the trailer from the topside?

3. What’s the best way to do the edges so you don’t have ugly seams? My trailer has some weird angles so not sure how to do the seams on the edges? Do you do the sides first and overlap on the top or do the top first and overlap over the top down the sides or both? Also how far should you overlap the canvas?

4. Where is the best place to buy the canvas and how many oz canvas should it be? I’ve also heard of people using bed sheets. How do you know what material to use?

5. Should I counter sink my wood screws? If so how should I fill in over the screw hole gaps? Also what’s the best way to fill in gaps between the Wood seems etc that I’ll have on the front and rear angles?

6. Any tips or tricks to doing this would be appreciated. Like how do you cut the edges to keep them from being stringy etc. or best way to do edges and overlaps.



Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm

Re: PMF over wood questions

Postby greygoos » Wed Mar 13, 2019 6:38 am

Type in PMF in the search bar above. There are lots of builds using that method.
greygoos
Silver Donating Member
 
Posts: 524
Joined: Sun Sep 27, 2015 6:15 am
Location: Syracuse NY

Re: PMF over wood questions

Postby lacofdfireman » Wed Mar 13, 2019 9:09 am

There are and I read for hours last night but like I said most were talking about PMF over foam. I’m doing it over wood. So I need to know if I should be doing “The Mix” before doing the PMF or not. I asked somewhere else and one guy say yes for sure and another says no because the paint won’t penetrate the wood like it’s supposed to. So I’m confused. And after having to strip my trailer once I don’t want to have to do this again.


Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby tmclemore » Wed Mar 13, 2019 2:27 pm

I used PMF over wood with great results. I purchased my canvass on Amazon and bought the largest size I could with no seams. https://www.amazon.com/gp/product/B01N6 ... UTF8&psc=1

I used TBII without thinning and rolled it onto the wood and the canvass to glue it down then followed with a 50/50 water and TBII to size the canvass. Once it all dried I used two coats of primer and 4 coats of porch paint.

I did the sides first and the overlapped the top two inches all the way around. I used a piece of pvc to roll the canvass onto and applied the glue in small section unrolling the canvass as I went along. Mine was on a standy so I think it will be much easier on your trailer. Be sure and press the canvass into the glue to make sure there are no voids. I used a bondo spreader to smooth out the canvass with the glue.

If you have to have a seam just overlap at least two inches. Try to put them in strategic places that way look they you planned it that way.

155749
This is my pvc/canvass roll
155742
This is the back side before gluing the roof on with an overlap.
User avatar
tmclemore
Teardrop Advisor
 
Posts: 70
Images: 49
Joined: Tue Sep 05, 2017 3:34 pm
Location: Somewhere in Texas
Top

PMF over wood questions

Postby lacofdfireman » Wed Mar 13, 2019 9:19 pm

Awesome thank you. I may try doing the gripper paint instead of the titebond 2. Not positive in that part yet. I think either way it will be good. Can you explain to me what sizing means? I thought it had something to do with the canvas shrinking but i guess not. Also did you machine wash and dry your canvas before using? Also what did you cut your canvas with? Thanks.

Here is my test board with a bed sheet and the gripper paint.

Image

Image


Sent from my iPhone using Tapatalk Pro
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby tmclemore » Thu Mar 14, 2019 9:14 am

I did not like the results of Gripper over wood. I tried it and could not get it to stick as well as TBII. I used the thinned TBII to make sure all of the canvass was penetrated with glue. I call that sizing but it may not be the correct use of that word. I did pre-wash my canvass. Although I don't think it is necessary. I did it because the area I was covering is so large and I was afraid the canvass would shrink and not cover completely or pull away at the edges. When I washed the canvass it did shrink about 5 inches each way. On a 12 x 15 canvass that wasn't that much in my opinion. I think you could get away with out pre-washing since your camper is quite a bit smaller. It may help pull the canvass tither and offer some structural enhancement.
I see some folks are recommending the use of epoxy and fiberglass. That was one of my choices in the beginning but after working with it a bit I decided on the PMF because it is less mess and easier to clean up. Also it seemed to be much more forgiving. Epoxy is hard to get off of your hands and the driveway and it stinks. I tend to be sloppy when I work with glue so I didn't want the mess. The price may be close to the same but having to wait for more epoxy when you run out is a PITA. Lowes is right down the street and they keep TBII on hand. Also be prepared to sand your butt off. I left my finish with the texture of the canvass. I'm not sure I could do that with epoxy. My trailer is a lot bigger and I was afraid I would have to sand everything to make it look smooth and finished. Not only am I sloppy but I'm also a little on the lazy side. :D

I think you will be good with which ever finish you decide to use, PMF or Epoxy. They will both work well in my opinion.
User avatar
tmclemore
Teardrop Advisor
 
Posts: 70
Images: 49
Joined: Tue Sep 05, 2017 3:34 pm
Location: Somewhere in Texas
Top

Re: PMF over wood questions

Postby tmclemore » Thu Mar 14, 2019 9:19 am

I forgot to mention I cut my canvass with a very sharp pair of scissors. I have a pair I use for leather that worked really well. I applied glue out passed my edges then used a razor to trim to the amount of overhang I needed.

155751
This is the window opening with the glue on it before trimming.
User avatar
tmclemore
Teardrop Advisor
 
Posts: 70
Images: 49
Joined: Tue Sep 05, 2017 3:34 pm
Location: Somewhere in Texas
Top

Re: PMF over wood questions

Postby lacofdfireman » Thu Mar 14, 2019 9:39 am

tmclemore wrote:I did not like the results of Gripper over wood. I tried it and could not get it to stick as well as TBII. I used the thinned TBII to make sure all of the canvass was penetrated with glue. I call that sizing but it may not be the correct use of that word. I did pre-wash my canvass. Although I don't think it is necessary. I did it because the area I was covering is so large and I was afraid the canvass would shrink and not cover completely or pull away at the edges. When I washed the canvass it did shrink about 5 inches each way. On a 12 x 15 canvass that wasn't that much in my opinion. I think you could get away with out pre-washing since your camper is quite a bit smaller. It may help pull the canvass tither and offer some structural enhancement.
I see some folks are recommending the use of epoxy and fiberglass. That was one of my choices in the beginning but after working with it a bit I decided on the PMF because it is less mess and easier to clean up. Also it seemed to be much more forgiving. Epoxy is hard to get off of your hands and the driveway and it stinks. I tend to be sloppy when I work with glue so I didn't want the mess. The price may be close to the same but having to wait for more epoxy when you run out is a PITA. Lowes is right down the street and they keep TBII on hand. Also be prepared to sand your butt off. I left my finish with the texture of the canvass. I'm not sure I could do that with epoxy. My trailer is a lot bigger and I was afraid I would have to sand everything to make it look smooth and finished. Not only am I sloppy but I'm also a little on the lazy side. :D

I think you will be good with which ever finish you decide to use, PMF or Epoxy. They will both work well in my opinion.


I’m 100% for the PMF. Epoxy in my case will just take way to long. If I had time on my side I’d give it more of a thought but I in a time crunch so I’ll have to go with PMF. I’m happy about that anyways. I’ve wanted to try it since the last trailer I built. I did have a little screw up yesterday during my reskinning. I kept reading about “The Mix” and kept reading about MinnWax. I had a small quart that was about 1/2 full and mixed it 25% MinnWax Urethane with 75% Mineral spirits. Not ever having done or used the Mix I recognized that the two weren’t mixing but used it anyways on where it would cover. Last night I learned that the MinnWax was water based and the Mineral spirits is oil based. Do you think the Titebond 2 will have issues sticking to that? I talked to a neighbor who told me basically the Mineral spirts would have pulled the MinnWax into the wood and I could put some oil based PolyUrethane and Mineral spirits over the top or just skip “The Mix” all together and go straight Titebond 2 over the trailer since I’ll be sealing the wood with the Titebond 2 and the gripper paint over that as well as other UV paint over that.

Did you do “The Mix” on yours.


Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby tmclemore » Thu Mar 14, 2019 10:47 am

I did not use the mix on mine.
I would let the mineral spirits completely evaporate before I tried to glue anything to the plywood. You could try glueing a small patch of canvas to the mistake and see how it adheres. It may work just fine. If it does the sand it off and pmf the whole thing. I'm not sure how the oil in the mineral spirits will affect the sticking of the TBII. Test it before moving forward.

Sent from my SM-G950U using Tapatalk
User avatar
tmclemore
Teardrop Advisor
 
Posts: 70
Images: 49
Joined: Tue Sep 05, 2017 3:34 pm
Location: Somewhere in Texas
Top

Re: PMF over wood questions

Postby lacofdfireman » Thu Mar 14, 2019 10:31 pm

tmclemore wrote:I did not use the mix on mine.
I would let the mineral spirits completely evaporate before I tried to glue anything to the plywood. You could try glueing a small patch of canvas to the mistake and see how it adheres. It may work just fine. If it does the sand it off and pmf the whole thing. I'm not sure how the oil in the mineral spirits will affect the sticking of the TBII. Test it before moving forward.

Sent from my SM-G950U using Tapatalk



Thanks for all your help. I ended up stripping the wood off and redoing it all. I needed to do it for peace of mind. I feel better now about going ahead with the PMF over raw wood. I’m still considering doing “The Mix” even though I’m not 100% sure it’s necessary. Seems like it’s about a 50/50 of people applying it first vs. those just doing PMF over untreated wood.

I’ve also decided to use Titebond 2 for the canvas vs. the gripper paint. Mostly because of cost. Titebond 2 is basically half the price compared to gripper paint per gallon so it seems like a no brainer.

I’m thinking I can get away with 2 of those canvas drop cloths you linked to. I did Howe’s find some cotton crop cloths and was wondering what their durability would be over the canvas. I have heard of people using cotton bed sheet so it may be fine.

Just curious what you filled your screw holes with? Is there anything you’d recommend other than epoxy?


Thanks again for your help.




Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby lacofdfireman » Fri Mar 15, 2019 11:22 pm

I have a question on where to start with the canvas on the sides of my trailer. It seems everyone is hanging the canvas above them and not sure if they are starting from the top or bottom. I’m just not sure how you’d work out the bubbles on the PMF unless you glues the entire side the put the canvas on and worked it all out at once. How would you unroll just a foot or so work out the bubbles or whatever and keep going. Seems like it would be easier to start in the middle and continue to work up or down. I haven’t ever seen a good YouTube video actually showing it being laid out on a trailer. Anyone have any insight on this?


Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby Homebrewer25 » Sat Mar 16, 2019 6:50 am

George Coe put up a good video on his foamie #2. Putting the canvas on the exterior starts just past the 2 minute mark.

https://youtu.be/IOTRwcs6oT4
It's 5 o'clock somewhere ... time for a :beer:

Steve
Noname Foamie Build (continuing spring '19): http://www.tnttt.com/viewtopic.php?f=50&t=70159
User avatar
Homebrewer25
Teardrop Advisor
 
Posts: 86
Images: 15
Joined: Thu Aug 18, 2016 4:08 pm
Location: Flag Pond, TN
Top

Re: PMF over wood questions

Postby lacofdfireman » Sat Mar 16, 2019 8:45 am

Homebrewer25 wrote:George Coe put up a good video on his foamie #2. Putting the canvas on the exterior starts just past the 2 minute mark.

https://youtu.be/IOTRwcs6oT4


Thank you. That gives me a way better understanding.

I was thinking if I have 2 of us my wife and I could just glue an entire side quickly then press the canvas on a side then start working out the wrinkles. I saw a guy on YouTube do this by himself but looked like the glue was drying by the time he got to putting on the canvas. I’d think if it wasn’t to hot you should have about 20-25 minutes to lay it all down before it was dry though. I figure we could roll glue on an entire side if two of us were doing it in about 5-10 minutes max which would give you some time to press the canvas into the glue and workout the wrinkles. Do you think that would work also? Anyone done it that way?


Sent from my iPad using Tapatalk
lacofdfireman
Teardrop Master
 
Posts: 134
Joined: Thu Mar 17, 2016 5:59 pm
Top

Re: PMF over wood questions

Postby tmclemore » Sat Mar 16, 2019 10:03 am

I used the roll from the top method and worked the bubbles out as I went down. Once the canvas has covered the whole side you still have time to work out the bubbles. I had no way to do the whole side at once before the glue became to dry to work with. It worked well and allowed me to do the job by myself. It's very forgiving and easy to work. I think that once you get started you will figure out what works best and may even come up with a better way to do it. Post pics and videos so we can see how you make it work.

Sent from my SM-G950U using Tapatalk
User avatar
tmclemore
Teardrop Advisor
 
Posts: 70
Images: 49
Joined: Tue Sep 05, 2017 3:34 pm
Location: Somewhere in Texas
Top

Re: PMF over wood questions

Postby Xanthoman » Sun Mar 17, 2019 8:12 am

For those curious, sizing is a term which relates to an interface binder to increase compatibility. In composites such as fiberglass and carbon fiber, the raw fibers are sprayed with a sizing to allow the fibers to be easily wet out by the matrix resin. Most of these sizing are dual compatible for epoxy or polyester but some are resin type specific so it’s good to verify that the fabric is ‘sized for [blank]’ before you purchase. In wood working sizing is typically used on edges to fill the porous substrates to have a better adherence surface for paints and finishes. Often times it is simply a wipe of wood glue on the ehenof mdf panels so it looks smooth. Several coats of primer are also sometimes used. In short, a sizing is any intermediate component to aid the bond or appearance of the finishing layer. (Primer is the sizing for drywall before paint.) The use of watered down glue to fill the pores of the fabric and fully wet out the system before painting would indeed be considered a sizing of sorts.

Anyhow, good luck with the trailer. It should turn out well.
Xanthoman
Teardrop Advisor
 
Posts: 58
Images: 3
Joined: Sat Sep 24, 2016 2:02 pm
Location: Rexburg, Idaho
Top

Next

Return to Skinning secrets

Who is online

Users browsing this forum: No registered users and 1 guest