I’m wondering which would have better peel strength (resistance to delamination)?
I’m going to do another poplar bender ply over 1 lb EPS board.
2020 flexes more…think about it
I’m thinking 2020 would be better, but would like some expert confirmation (from experience). Not everything I think turns out to be true.
delam happens when the glass flexes into the foam and bounces back. over time, this will cause separation.
the 2020, being more flexy, will delam quicker than 2000.
i use both 2000 and 2020. 2000 for the lam. i save the 2020 for the gloss (it polishes up a little better…and may even offer some added ding resistance should the board get knocked around).
delams don’t happen as soulstice describes.
delams happen either at the foam/laminate interface, or just below that layer.
the first scenario is a bad bond between the foam and resin. this can either be adhesive/substrate incompatibility or it can be contamination at the interface.
the second is a result of the inability of the core to handle shear loads.
as far as delamination is concerned, chances are they’ll both fair about the same.
as far as heel denting is concerned, a 2020 laminate will be more flexible…so if the core isn’t going to spring back (ie polyurethane), then you’ll have more heel dents.
as far as impact resistance is concerned, 2020 will be more likely to flex; bend. 2000 will be more likely to crack.
and as far as polishing is concerned…that all comes down to barcol hardness; there aren’t published numbers from RR on this, but in my experience, Ad F. increases Barcol hardness, and 2000 certainly feels harder to me than 2020.
better polish with 2020 comes straight from Greg Loehr…i didn’t ask why or how.
delams resulting from glass pulling away from pressure dents / foam collapse is the only delam i’ve ever had to deal with. it’s gonna happen…eventually.
i’ve never used eps, and i know that, unlike pu, it will spring back. on the other hand, it has to be sealed with spackle. i doubt if the resin will bond to spackle as well as it would to foam. so, wouldn’t it go to reason that the more it flexes, the sooner it will begin to pull away from the spackle/eps?
Not all EPS has to be spackled…
Correct me if I’m wrong, but don’t you get a better bond if you use a mixture of epoxy/microballoons/cabosil in a paste to seal than if you use water based spackling compound?
I have not de-lammed a board yet using the epoxy mixture, though I’m sure it can happen with abuse.
Also if you can afford the weight, why not let a bit more resin sink in to the foam, like brush a thin coat of resin on the blank with a brush, then use the thickened mixture above it before it hardens. What’s the most you’ll get …a few more ounces of weight … beh … negligible … but you will have more bite into the foam.
Just my thought … I’m by no means an expert so take it with a grain of salt
Billy
Quote:
Not all EPS has to be spackled…
all 1# eps needs to be filled (unless it’s the core of a compsand)
" Not all EPS has to be spackled…"
werd. and 1# is completely unsuitable for a “shape and glass” program. it’s sandwich or nothing with that stuff.
and plenty of the lightweight spackles contain ammonium salts…amines…which will chemically bond to epoxies…my tests showed failure between the spackle and eps; not the epoxy and spackle…and I make sure that the contruction transfers the loads to the skins, be they sandwich or just glass layers.
as far as allowing resin to penetrate the foam; it comes down to what kind of a structure you’re wanting to build. If you want one that is stiff and can handle static loads, then by all means, go ahead and let the resin penetrate. If you’re looking for one that can handle dynamic loading, then you definitely don’t want to lock the shear in your core up; the core won’t be able to handle the load. You want the core to transfer the load to the laminated skins where you have fiber reinforcement and material that is specifically designed for this purpose…
those few ounces of added weight that you think are creating a better bond are actually going to make a stiffer board that will be more likely to snap under heavy loads. basically, it’s just a matter of time until that board delams somehere inside the core…and I’d way rather repair a board at the periphery than on the inside…
read it, learn it, love it, get your questions answered.
http://www.antonio.licciulli.unile.it/Corso_Ceramici/relazioni/materiali%20compositi.pdf
and check wikipedia for words you don’t understand.