Hi, not to hijack the thread but got an xps question, Sold a board a couple of weeks ago and the kid who bought it has sent some pics back asking what these dings are, looks to me like pressure dings but the sanding coat is cracking around perimeter of ding. Hope the pics show up the problem, anyone had anything similar and if so whats up with this? Thanks for any help in advance…
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looks to me like pressure dings
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I’d say pressure dings too.
What density foam?
Its chinese Xps I think , but not sure on density, pretty hard so surprised to see it pressure ding…
I’ve only seen circular cracks like that in poly glosses?
Hey Nocean did you have a particularly thick filler coat on there, or do it twice?
JD
Hi, thanks for the replies , yes its poly over epoxy lam. Speedy, I think I may have done a sanding filler then a top coat of filler over to get most out of sanding so two coats , is that why its cracking rather than pressure dinging, dont think it will effect the water tightness but might flake off which is my main worry?
Yes it may flake off, that’s why you should never do poly over epoxy.
looks like a dent. i didnt know that we were so suposed to make dent proof boards!
Yeah Josh isn’t it from a thick sanding coat? Mals with a thick gloss coat golf ball dent like that.
Also…not a major scientific finding but the white XPS Paul is using/talking about is different to the blue stuff Wardy is on…are people debating different materials?
We had white xps from Dow in the late 80s, the ''new'' stuff is not really that ''new''. White, blue, pink, whatever....
Ask the manufacturer how it's polymerized.
Hey Mike.
I sense an aura of dislike towards XPS foam…
And I couldn’t agree more… I hate the stuff…
Bend a 1" or 2" thick piece of 2# EPS to failure…
Now bend a 1" or 2" @ 2# density section of XPS, ( the same thickness as the eps) , to failure…
Which breaks / fails first, but more importantly, which fails more violently ??? Or should I say… “explosively”
XPS is poor in “shear” and has limited “cycle elasticity” …It was designed as rigid/water resistant insulation, not as a surfboard core…
I’ll say it again… I hate the stuff !!
This would be in contrast to the uniform density of polyurethane blanks and the water resistant properties of polyurethane and expanded polystyrene.
Hey nocean…
I’ve been following your board builds, and they look great…
Don’t ever “top coat” an epoxy board with a poly hot coat… If you’re going epoxy, go epoxy, all the way…
I’ve never seen those circular dents on a epoxy board…
Nocean I repair a board with same problem on EPS: Light lam deck and poly hotcoat. Glass epoxy can move much than polyester before crack so if epoxy lam is too thin then hot coat crack. On this board i put a 2oz patch over after good sand and no more problem.
Never have real problem with poly finishcoat over epoxy filler coat. Poly give a nice friendly finish easily and a better protection to UV. I have some all epoxy badly yellowing, and that’s a real problem.
Sorry for my frenglish
Thanks lemat, really good advice , thats what I needed to know! I think poly over epoxy can work fine I just think it has to be sanded well between and washed from what ive heard and read.
Cheers, a bientot:)
Why would anyone do a polyester hot coat in this day and age? It’s not as strong, as light, as reliable, and it’s not faster or any easier. And it yellows worse than a top flight epoxy.
And I totally agree Paul. XPS? Been there done that.
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Why would anyone do a polyester hot coat in this day and age? It's not as strong, as light, as reliable, and it's not faster or any easier. And it yellows worse than a top flight epoxy.
And I totally agree Paul. XPS? Been there done that.
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*shrug* it's pretty
Greg, i use now your resin (2000 and now KK), it’s a really good product, i work in good condition and i do both all epoxy and epoxy with PE finish (glosscoat). What i can say is : board with epoxy finish coat yellow more than board with PE finish coat and PE finish is faster to do (faster to sand) and cheaper. People wich buy my board like PE touch and (maybe) smell. So i do my finish coat with PE on well cure fresh sand epoxy filler coat with no real problem. All peel off problems i see was hot coat PE on thin epoxy lam.
Sorry for my frenglish
Howzit Greg, Gary Mcnabb of Nectar Surfboards was doing them just like that back in the early 90's. Doesn't work since I had to fix my friends board a few times after it flexed to much and a few 8" diameter circles of resin just popped off. Aloha,Kokua
I have a bunch of 4" thick 2’ x 8’ DOW Styrofoam XPS Billets for sale in SoCal if anyone wants to test their skills with XPS. Check out my ad in the “Materials” section of the Surfshop.