NFRP / PolyWall for top skin?

[WebFoot]

Ive found plenty of info here, regarding the use (or not to use) of FRP for skin, mostly for those living in hot areas. People who have used FRP in cooler areas dont seem to have near the issues of oil canning.
But, Ive found a product along the same lines that I wanted feedback/opinions about.
Its made by parkland plastics (parklandplastics.com) called Poly-Wall.
Its a smooth thin non-fiberglass flexable poly in 4x8 sheets...almost feels like the flexable bumper type plastic on some cars. MUCH more flexable then FRP of the same thickness and not semi-brittle like some FRPs Ive seen. The stuff is impervious to everything from bugs, to water, to rott, chemicals, etc. and cheap at less then $20. a sheet. I dont know the UV abilities, but it is advertised for room/garage use..areas that do get some direct & indirect UV...
Anyone have any 1st hand experince with it?.
Im thinking skinning it, fully glued down as a final layer on a sandwhich construction, since my area of travel will be anything but really warm or high in UV exposure.
TIA,
Webfoot

[madjack]

WF, many of us have checked it out...Sid and Side actually used it and had lotssa problems with oil canning and the BIG ONE...most glues and adhesives wil not stick to it and the manufacturers recommend welding to make a sealed joint...it is cheap but comes with a host of problems that are not all surmountable..........YMMV
madjack

[WebFoot]

Madjack,
Thanks for the quick reply. Ive followed many of your post & have learned much from you already!
I feel a little stupid now, having searched this forum more following my inital post, I found a few previous entries about this stuff. It looks great at first doesnt it, and I think it has potential under the right conditions!
Do you think the oil canning of such a solid material is an effect of trying to float the product like aluminum (or not getting complete adhesion of all possible areas to the under skin) ? from those that have tried it, I wasnt able to determine how it was actually applied.

I can plastic weld pretty good, that horizontal seam to mate the roof sheets would be a long one and could be tricky to get it perfectly straight visually, maybe white H-track would be a better there.

I was thinking "if" I could use it, of a major glue down under negative pressure (vac bag) fully trimmed, maybe to include nylon rivets or similar into underside cross braces alighned at intervals. might just keep it tawt & tight on the under skin, yet able to flex as nessicary..manufacturer suggest 1/8 inch expansion gap. My guess is, one might be able to finish it in automotive paint..like that used for fiberglass cars (vett, fiero,etc) to provide a longer lasting finish with some UV & thermo protection which would keep its neg properties at a minimum.
Your thoughts?
Webfoot

[madjack]

...oil canning is mostly a function of heat generated expansion...in the case of AL, if floated and it oil cans, it will return to normal after cooling..it even seems to "find" it's own best fit...while the plastic stuff looks great at first glance, it really seems more of a problem than not...I emailed 3M and SikaIndusties about adhesives for this stuff and was basically told that nothing would hold and they actually used the material for test purposes, since nothing would stick to it....

Like ya said, it looks great, is cheap, can be had in bigger than 4x8 sheets, it's just that research and experiences say to fahgetaboutit...as always, Your Mileage May Very
madjack

p.s we did have a member who seemed to be having some luck using 3M VHB tape to stick the PolyWall down....o'course, I haven't seen him around inna while

[sid]

Here's some good... no, great advice... don't use it.

There are three of us here that I know tried it, with different adhesive techniques, and none worked. It is a "virgin" product and has a mind of it's own in different weather.

Believe me, it ain't worth the headaches.

[WebFoot]

Sid,
So was your trouble with this product an issue of keeping it flat/down? due to not being able to find any suitable adhesive. Was this lateral movement also or just bubbling / oil canning?
What about UV damage, etc?.
Not that I am now considering the use of it, but I was thinking of 1/8" large head nylon rivets thru 1/4" holes 9for exapnsion) sunk thru & into spars spaced underneither the plywood underskin in conjuction with a flexable glue...the rivet aspect is what I dont think anyone else has tried except for those guys building look alike Aluminum WWII style TD's, but is should/would limit movement of an otherwise large unsecured down areas if the adhesive let go.
Webfoot

[sid]

I had some limited lateral movement, but only because of the bubbles (I would really call them veins). I had to fix the bottom rear of the hatch because it pulled out from the trim due to bubbling. I guess it would depend on how far apart your spars are, because the heat will really make it ripple/bow/bubble/vein/warp..... given the smallest area.

It's not a very pretty site after you spend all that time on the interior and the galley, only to have the outside, what people see first, look bad. I installed it when the weather was cool and it laid down fine, but when the weather warmed up that's when the problems started.

Sid,
So was your trouble with this product an issue of keeping it flat/down? due to not being able to find any suitable adhesive. Was this lateral movement also or just bubbling / oil canning?
What about UV damage, etc?.
Not that I am now considering the use of it, but I was thinking of 1/8" large head nylon rivets thru 1/4" holes 9for exapnsion) sunk thru & into spars spaced underneither the plywood underskin in conjuction with a flexable glue...the rivet aspect is what I dont think anyone else has tried except for those guys building look alike Aluminum WWII style TD's, but is should/would limit movement of an otherwise large unsecured down areas if the adhesive let go.
Webfoot

[Bodyman]

As Sid said. Don't use it!!! It is not worth the problems!!!
I found that quality spray on vinyl roof adhesive does adhere well except when it is in the sun the stuff expands so much that it pulls the glue and even the laminate in weak areas and you end up with large bubbles (2" to 12"). The problem with using the good adhesive tape is it expands between the tape strips.
The same would happen if you used plastic rivets. They would not allow for expansion either.
I have heard of no problems with FRP(fiber reinforced plastic) but it is not the same stuff at all
Randy

[WebFoot]

Thanks Guys,
Im no longer considering it, but was more or less wondering if it was a problem that could perhaps get worked around with a different approach...but like a few things, I am learning if thier was a way, someone would have already found it..lol
I can get FRP locally, but had concerns over prolonged UV exposure & things turning yellow & brittle.
Webfoot

[Boodro]

Webfoot. i had FRP on my TD for about 3 years. it sat out most of the time. i had no problems with yellowing or it turning brittle or chalking. It cleaned up & shined when washed & it sat under a cherry tree . You can paint it with some prepping too. I just changed to woody sides this past spring , cuz I liked the look better. check out my album & you can see the difference. Good luck on your build!

[WebFoot]

Thanks Boodro!
Did you use the normal white FRP found at HD or Lowes? It does seem as though "FRP" tag line has been applied to a multitude of products, many of which are not the same. Curious as to what you found which seems to have worked so well. What did you use for adhesive?
Id imagine most anything would go bad if left outside to the elements without some prep & care. Steel rust, Aluminum oxidizes, Plastics break down, Wood rotts. My general area doesnt ever see hi-temps (anything above 80* is a heat wave) and even less direct sun most of the yr.
If I go with FRP it will get a nice coat of auto paint (which will help seal it all also) & fresh coats of UV protectant auto wax as needed..which Id imagine would have major effect on reducing any UV damage down the road.
Webfoot

[Boodro]

Webfoot, Yes the FRP I used came from Lowes( 28.00 per 4x8 ) I bought the FRP Panel adhesive from Lowes. Don't recall the exact brand. I troweled it on with a 1/4 notched trowel. Then clamped the 2 sides together with straps & 2x4s from side to side. I should have glued the walls & FRP before I cut & mounted them. It would be easier to clamp. When I stripped the panels off , I found where water had gotten under the panels along the bottom edge,( the bottom edge did not seal properly)the adhesive had separated from the panels. so makes sure the edges are completely sealed very well. Good luck on your build. We'll be watching.