Hey all,
I’ve recently done a skate deck with some carbon fiber/epoxy, however after leaving it to cure for months in the garage, when my son finally finished it off and took it out he reported that the resin softened when it got warm in the sun, goes hard again when it cools. Any ideas or suggestions on how to sort this (other than only ride it in the cold).
The epoxy is just some that I got cheap from a mate, it’s made in the UK by Polyfibre, phoned them for advice but no use at all.
Advice appreciated.
Peace!
Thats a new one for me, maybe it wasn’t mixed well enough or it was too cold when you did it.
All I can sugest is canding it off and starting over with better epoxy. Epoxy can get soft at high temps but not the sort we get over here in the winter.
It’s think known as the glass transition temperature of the epoxy. In general this temperature is 50-80 Celsius before the epoxy goes soft for room temperature cured epoxies, higher if you post cure at higher temperatures. However, it seems to me that it might be lower if the epoxy is cured at low temperatures, if the mixing ratio is a bit off, in thin laminates(hotcoats) or if it’s not completely cured (which might actually be the case for the other cases too). It also seems to me that some epoxies have more of a tendency to this than others. West f.ex. seems to cure hard even at low temps and when you are a bit off with mixing ratios while some other ‘generic’ epoxies I’ve used are much more sensible to temperature, mixing ratios and time. Fast setting epoxies like 5 minute epoxy needs a good bit longer than 5 minutes before it can be sanded, else the temperature generated by sanding will make it gooey almost to the point of being runny.
As for a solution to the problem at hand, I don’t know if there is one.
regards,
Håvard
Thanks for the replies, sort of what I expected…No matter, it was only a skeate deck, rather nice one though…Cold day skating only it is then.
Peace!
Yep, that’s what post curing is really all about. Not only does it cure most epoxies to a harder finished state, it allows the resin to withstand higher temperatures before getting soft.
The foam composite airplane guys (Burt Rutan, etc) are big on post curing for that reason. You don’t want an airplane softening up in mid-air and coming apart.
Thanks John, any more thought on that logo? I’ve just finished the art work to go on my current project so could do with something to sketch about with.
Peace!