another material for covering ...

[rruff]

Problem for me would be shipping as I'm in remote area. Shipping would most likely be a deal killer.

Not serviceable by ground on the US? Shipping could be fairly decent because the material can be rolled.

[GPW]

Rruff, it’s about thick as the cardboard backing of a writing pad ...The thinnest ... the nice stuff ( JMHO) is about twice that thick ... The thinnest would work , but if people are going to go beating on it or poking it to test “puncture resistance” then the thicker would be more appropriate ... I’d suggest waiting (if you can) till my friend gets his boat built from this stuff ... that would be a good test ... I think ...

Shipping is always the problem ... Maybe contact the manufacturer and see how they ship the product .. ?

[doug1985]

Hmmm....following this one. I am looking at starting a build in a couple of months and have a dream of using Filon sips (I have spent too much time on the styromax site), but at around $1,500 CAD for a 40' (340sqft) roll it is a little out of my price range. IF this could be shipped to Canada and the boat build works out, I would be very interested.

Doug

[rruff]

But then with Filon you still have edges to deal with where a hand layup of resin and glass is probably the best way to go.

My current front runner is just a hand layup of epoxy and fiberglass, with big box foam. I thought it would be expensive but after much searching I found you can get viable epoxy for <$50/gal and 1708 cloth (17oz biax and 8oz mat) for <$5/sq yd. A single layer of that is a pretty stout 1mm thick surface.

I think most people shy away from epoxy and glass because the stuff is no fun to cut and sand, but you can avoid the worst of that by just not worrying about a flat shiny surface. PMF covering isn't shiny either.

[KCStudly]

IMO, there is no free lunch.

If you want smooth and lump free, it's going to take a lot of attention to detail and prep work, no matter what substrate you choose (wood, PMF, glass weave, etc.).

Even aluminum (and aluminum faced composites), Filon and the back side of FRP (which isn't really that smooth) will require effort to achieve a good fit and finish; and these all require some sort of trim or additional hand work at the edge joints. Since I don't like the thought of potential leak points in trim, and (on paper at least) trim adds cost, I didn't go that way.

Even if a textured surface is desired, like with canvas or glass weave, it takes a lot of attention and care to have a good base, and uniformity at seams/overlaps and edge transitions/wraps. Then, if you end up using a little putty (filler or whatever) you end up with a smooth spot that breaks up the continuity of the texture (catch 22).

Like any painted (or other high finish) surface, the final result is only as good as the prep work and attention to detail that goes into all of the stages.

Face it, body work sucks. There, I said it.

I'm doing epoxy and glass over foam and wood, in a theoretically monolithic outer skin shell, with rounded over profile edges to eliminate trim. After getting the base reasonably fair and smooth, and laying up two plies of glass with the profile corners wrapped, I'm at the stage of filling the weave. I'm using West System's 410 filler troweled on. Not the best solution for vertical surfaces; if you don't get the amount of thickener/filler right it tends to slump. I haven't tried spraying high build filler/primer, but keep threatening to in my mind (... I had already bought a large amount of epoxy, so am continuing that way instead of spending even more money on spray gun and supplies). Mind you, I'm not going for a killer automotive grade paint job, just smooth and even with no glaring garbage.

From the perspective of a novice paint and body worker, I can fairly say that if you want it to look good, regardless of which media you choose, plan on more work than you might think initially.

Sign me,
KC the wanna be pseudo perfectionist

[OP827]

Perhaps we could have the best of two worlds: use these more economical fenolic sheets, put a smal radius (1/4"?} on the corners and cover them with epoxy bias glass cloth? That way I would not need to spend time filling the glass weave and fairing foam prior to that. That is what I beleive Michael had done with his Astroliner build here, except he did not round the corners, just forced a sharp corner with his great laying skills with carbon fiber and he used filon instead of this sheet.

I just like the fact that I could throwel a glue to foam, glue the skin down and mostly be done with "body work" and fairing right then. Fairing corner strips is much less work than a whole body. Just thinking here.

[OP827]

Yesterday , we got to see the material samples , and they seem to be pretty good ... Three thicknesses , the thickest way too heavy unless you're e making a TANK ... The thinnest is a bit on the thin side yet still stiff though ... The middle weight seems to be “just right”...
The price is $1.25 a square foot for the thickest material ... so is “affordable” ...
Curiously the surface has a light texture that would likely be great for gluing , So far as we know Epoxy is the glue , which gives advantage for perforating the foam , and forming “epoxy nails” better securing skin to foam ...
My friend is going ahead with his boat idea , so we’ll follow that as it happens ...

According to product properties, this Phenolic fiberglass sheet should be stronger when compared with the same thickness Filon(which is polyester resin with glass mat and UV resistant gel coat).

[rruff]

KC the wanna be pseudo perfectionist

Your build is a beauty, though! I may end up doing a similar construction method though not near as nice. I'm thinking a coat of Monstaliner over the epoxy would hide a lot of "sins". One of those sins I think will be foam expansion and contraction, which will create a discontinuity with the wood stringers (spars). Not just from temperature, but altitude! I live at 7000 ft. I got a sample of PP honeycomb (Nidacore), and every cell was puffed up. Pretty sure the closed cell foam is puffed up too, but it isn't obvious.

What did you use to fair the foam before the epoxy and glass? Did you texture the foam first?

Bringing it back on topic, gluing on a hard composite sheet vs hand layup can make it a lot easier to acheive a smooth surface.

[Tempest]

WHOOOOAAAAA! What's this about altitude and foam expansion / contraction? I live at 5K and regularly will be using the foamie up to 10K. Is this an issue with foamies?

[GPW]

" One of those sins I think will be foam expansion and contraction, which will create a discontinuity with the wood stringers (spars).” Interesting ??? All these years now , nobody has reported any such problems as we can recall ... A lot of the expressed anxiety about foam is just unfounded in the real world usage .... If there was a problem , surely somebody would have reported it ... certainly Everything else is ...

I talked to my buddy Vinnie ( boat) and asked him about the flexibility , and he said he bent the thin piece up to 90 degrees , and although he heard cracking it did not let go , and when returned to flat , still was all joined (memory? ) We’re going over there today with a camera to do more testing ...

And JMHO , I just want a durable rot proof camper that can live outside ... if it’s textured or not , I don’t care ... I wanted to originally do one in Jute coffee sacks ( free) , which would have been Very Textured .. So Build/finish like YOU want to ... We all have different masters to please ...

[dancam]

Bubble wrap or large cells maybe, but i dont believe the pink or white foam is an issue. The white expanded styrofoam seems to handle 28in hg fine, and doesnt start collapsing until about 30psi of pressure. It gains most of the volume back when the pressure is released. Havent tried the blue foam though.
Sea level atmospheric pressure is 14.7 psi, at 10,000ft its still 10psi.
The deflection pressure of our foam is 20-40psi and were talking a difference of 4.7psi sea level to 10k ft.
Deflection pressure of bubble wrap or nidacore isnt much as far as i understand

Sent from my SM-G920W8 using Tapatalk

[rruff]

" One of those sins I think will be foam expansion and contraction, which will create a discontinuity with the wood stringers (spars).” Interesting ??? All these years now , nobody has reported any such problems as we can recall ... A lot of the expressed anxiety about foam is just unfounded in the real world usage .... If there was a problem , surely somebody would have reported it ... certainly Everything else is ...

It would only happen if you had wood spars that went to the external surface along with the foam. Foamies generally do not. KC mentioned this in his build thread, due to temperature. The perfect surface he was trying to acheive would be altered by a temperature shift. Altitude should make a bigger difference. It is cosmetic, I doubt there are any structural problems.

[QueticoBill]

Probably belongs in another thread but I too am concerned about the dimensional stability of XPS in my build. I've seen large stressed skin panels - 4 x 8 and larger - literally tear themselves apart. TO be fair, they were aluminum fame (perimeter only) and the solution was to use slotted connections of the frame. I suspect that it hasn't been a problem for most tear drop builders because most - based on what I've seen here and specifically reactions to my comments about a sparless roof that relies on just the foam and skin bond - really rely on the spars and the foam is along for the ride. PL adhesive promotes itself as elastic, so the dimensional stability may not be an issue because of the non-rigid bond. PMF would seem to be elastic also, and move with foam. In the end, most foams used are noted as moving 2% in size, and many seem to shrink as they age. Poly iso seems even less dimensionally stable than XPS, which is noted as maximum 2% linear change - which is less than 1/32" in 1 1/2" and maybe not that much different than wood of equal thickeness, but quite a bit over 60".

Considering the formulas for stressed skin panels made with wood framing seem a little more developed and accessible ( https://www.apawood.org/publication-search?q=U813&tid=1 ) I may decide to forgoe the sparless idea and make sure the foam isnt to snug and well bonded. On the other hand, the true foam core only stressed skin panel has an appeal to it.

[rruff]

Probably belongs in another thread but I too am concerned about the dimensional stability of XPS in my build. I've seen large stressed skin panels - 4 x 8 and larger - literally tear themselves apart. TO be fair, they were aluminum fame (perimeter only) and the solution was to use slotted connections of the frame.

Can you describe what was happening there in more detail? What was the skin? What was tearing apart from what? What caused the change in dimension?

[ghcoe]

I have a few expansion issues with my build. This picture is a point where I had to butt two pieces of dry beading together. I used beading to harden the corners and had to butt a short piece in because the beading length was just a bit too short to go the whole length of the roof. This was taken in the morning and by afternoon it will be nearly unnoticeable.

Expansion

DSCF4613.JPG (155.92 KiB) Viewed 2562 times

I installed a door in the morning and by mid afternoon it was hitting on the body.