How to get good looking PMF?

[iconicflux]

I really like the idea of PMF but I've seen a PMF build in person and while I was totally okay with any of the dents and such that were showing I know that my wife would be less understanding about things like dents showing, fiber weave showing (maybe), etc. Essentially, we have differing priorities where I lean towards functionality first and she leans towards aesthetics.

So how do you get REALLY good looking PMF? Can you have the overlaps on the edges be where trim would go without losing strength?

Is there a way to do PMF without the large weave of the canvas showing through or do you need to coat with something like Monstaliner in order to get away from the weave showing through?

Thanks!

[tony.latham]

This is Monstaliner over fiberglass.



I think it will hide PMF weave. It won't hide the seams. You would want to use their primer.

Glassing isn't any harder than PMF and will cost roughly $75 more.



Tony

[TimC]

Start with quality canvas. I used the drop cloth stuff from Menards. It's ok for the look I'm after; after about six coats of latex exterior paint the weave just shows through. On my son's td we bought good quality canvas. Very consistent weave without the little bundles you often see on the drop cloth quality canvas. We bought the good stuff from bigduckcanvas.

Tim

[OP827]

One builder used cotton webbing to cover seems which looked better than a typical PMF canvas overlap. I am not sure if monstaliner is a great idea over PMF due to compatibility of glues.

[Pmullen503]

If an glossy, automotive kind of finish is important then you shouldn't start with canvas.

+1 on starting with quality canvas duck. You can buy it wide enough so the only seam is down the center on the roof where it will be less noticeable. You can fill the weave with something like gesso or just lots of paint. Use flat or semigloss paint, carefully do your corners and use trim and/or paint scheme to make overlaps less noticeable.

You don't say if you are going over wood or foam. If wood then fiberglass is a more straight forward path to a smooth finish. PMF/foam has a great many advantages but if finish quality is paramount, then other materials will be better suited.

[iconicflux]

I haven't decided 100% about the walls yet. I'd like to do something really lightweight so I've leaned towards foamie for years but as I have been planning this out I've figured out that a foamie would have some limitations for mounting cabinets/storage that could be a real problem. I might have to either embed 1x2's into channels in the foam or go with furred out walls.
Foam would certainly be lighter weight by about 400 lbs.

How hard is doing your own fiberglass? Is it roughly the same difficulty as PMF?

If an glossy, automotive kind of finish is important then you shouldn't start with canvas.

+1 on starting with quality canvas duck. You can buy it wide enough so the only seam is down the center on the roof where it will be less noticeable. You can fill the weave with something like gesso or just lots of paint. Use flat or semigloss paint, carefully do your corners and use trim and/or paint scheme to make overlaps less noticeable.

You don't say if you are going over wood or foam. If wood then fiberglass is a more straight forward path to a smooth finish. PMF/foam has a great many advantages but if finish quality is paramount, then other materials will be better suited.

[OP827]

I did fiberglass and it is quite easy, especially if done on a flat surface. Glass cloth lays flat with no wrinkles and gets saturated with epoxy, there are many videos about how to do it.

[RJ Howell]

I agree, use quality cloth and it will come out better. That also removes the 'poorman' from the equation, lol. Tony's estimate between costs is really close as I have experienced (my last project I glassed over foam). I also debated using trims and bought a couple different plastic drywall style trims I'm familiar with. I gave in on that idea do to the cuts/joints/miters and decided to just lap my canvas. I also did not come up with a good way to attach any faux wood over that pleased me. Trim over seams was a no-go for me.

Quality cloth and clean cuts at the overlaps can look good! I have decided I like the look of the canvas (duck cloth actually) and found if I watch the sales, I can get it at a decent price. I ended up doing a sponge paint finish on my last build to get a 'camp' look. That one I glassed and laughed at myself for the effort to make it look like PMF..

MHO only and what I have learned along the way.

[Pmullen503]

..............

How hard is doing your own fiberglass? Is it roughly the same difficulty as PMF?

It depends. If you are going to paint or otherwise cover it, it's not bad. Drips, runs, sags can be sanded smooth and recoated with epoxy. If a spot is starved of epoxy it will always show but who cares if you plan to paint. So you can get a decent result your first try. It might just take more time and materials than if you had more experience. Lots of videos to show how it's done.

If you want a clear finish, then you should definitely practice first. The choice of epoxy, cloth and how you apply it will make a difference in how clear your final result is. It's a good idea to practice on some shelves or a tongue box. The most important part is not working air bubbles into the epoxy during mixing or application. That will leave a cloudy appearance. If you get a drip or run you can sand and recoat but it will show. Someone else may not notice it but you'll know it's there. I've built 11 wooden boats with a clear finish and my last is noticeably better than my first so there is a learning curve if you want truly perfect results.

All of the foregoing remarks assume a wooden teardrop. Even though I have around 30 years experience with epoxy/glass I chose to cover my foamie with canvas. Three main reasons: The foam you buy is not perfectly smooth. In particular, the lettering is stamped on and can telegraph through unless sanded off. It's difficult to sand a large surface with hand held sanders if you want it truly flat. It's bad enough with canvas but it will be less noticeable. Second, sanding something hard like epoxy over a soft substrate like foam is more difficult if you do get a run or sag. So if surface appearance is a priority, I'd recommend glass over wood especially on your first large epoxy/glass project. Lastly, canvas covered foam really is self repairing. Small dents will fix themselves over a few days in the sun. More serious dents can be healed with the judicious application of steam.

Several builds have used glass over foam and have come out great. I just think foam and canvas compliment each other in terms of each materials' characteristics.

[iconicflux]

The roof is about 7'6" across and i havent seen fiberglass cloth in sizes wider than 60".

Is there any other kind of cloth that could be used?

Thanks

[Pmullen503]

Overlapped seams in fiberglass can be sanded flush so it's not essential to have full width cloth. With canvas you really can't just sand it smooth so you should plan and execute overlaps carefully.

[iconicflux]

Thanks for the info. Im a total noob to fiberglassing. Going to look at what i can practice with to figure it out.

Overlapped seams in fiberglass can be sanded flush so it's not essential to have full width cloth. With canvas you really can't just sand it smooth so you should plan and execute overlaps carefully.