Anyone experienced with fiberglass? (help)
-
so i'm building a loft in a bedroom (or maybe its just a fancy bunkbed?
) and in order to keep a lowish profile on the railings, i've fiberglassed them for added strength..the railings were attached to the post in a mortise/tenon style using a slower setting epoxy (30 minute working time.. 24hr full cure as per the label/instructions)
the railings were attached then left to set for over 24 hrs prior to doing the glass.. my problem is now, the glass won't harden in the areas near the joints (where the epoxy was used)..
it's been over a day and a half and it's still un_sandable in those areas..
the resin i'm using for the fiberglass is fibre glast's #83 polyester laminating resin.. the room is slightly cold so i've added a little extra mek (1tsp per 12oz as opposed to recommended 1tsp per pint)
it seems as if the polyester resin is melting or reacting in some way to the epoxy which is preventing it from curing..
so, anyway.. what do i do now???
thanks(i'll try some other forums too but i figured i'd start off here.. if i get ahold of a knowledgable person elsewhere, i'll report back here
)
-
Jeff
I did some fiberglass boat layup with my dad, and I'm wondering...
Its been years, but if I recall correctly, most polyester resins contain wax, we sometimes would epoxy wood transoms on the fiberglass hulls, when we applied polyester over epoxy he would use a "tie coat" resin.
Sorry can't remember exactly what, and I know this won't solve the problem, but maybe there is a product that can be applied over to assist the cure. -
hey Dale.. nice.. i think the tie coat is what i'm looking for..
i just received this from tech support at the supply company
@unknownuser said:
Polyester and Epoxy are not compatible! Polyester will not cure properly when they come into contact with an Epoxy that is not completely cured and scuff sanded. On another note, Polyester will not bond well to Epoxy. So all issues can probably be traced to the resin incompatibility and cold temperatures. We do not suggest using our resins in temperatures below 65'F. I hope this helps.
to which i replied:
@unknownuser said:
i've managed to cut back the fiberglass in the problem area and wiped off most of the excess resin..
i guess at this point i'll just wait a week or so before i spot check an area to see if the resin will cure at that point..
i'll also look into some sort of barrier i may be able to put around the joint which will stick well to the epoxy as well as the polyester resin but will keep them from coming in contact with each other..
maybe your OM has an idea in regards to this?
thanks
jeffso, it seems as if this barrier coat i imagine is actually a real thing and it's called a tie coat.. i'll search around
thank you!
-
I would remove the retarded 'gel' initially, mechanically by scrapping with a Stanley knife blade to remove the polyester/Epoxy mix bulk, and then and then thoroughly clean with GP thinners (the thinners will not effect the thermoset resin, sure you know that though) let it dry and sand the whole thing to give it some tooth. I would then coat it with polyester resin again, sand, re coat, sand, final coat. Not an Industrial Chemist but that's what I would do.
-
hey steve,
thanksi've done (am doing) some of what you suggested already.. i cut back the glass which wasn't curing then used some acetone to get rid of most of the goop.. i'll be down to bare wood again soon.
another guy at a boat building forum has said epoxy will stick to polyester but not the other way around..
i'm thinking of either a) finishing off the railings posts with the polyester (which i already have) but staying away from the joints.. then using an epoxy resin in those areas which i'll be able to overlap onto the polyester..
or b) doing the entire second coat with an epoxy resin instead of polyester (probably the best idea but i just don't have the supplies on hand to do it right now)
-
Hey Jeff, I was assuming that the joints were done with epoxy and the glassing was done in
poly' is that correct? If that is so, I think if the cleaning is done sufficiently well, the remaining epoxy will be in such small amounts (in the cells of the wood) that the polyester will not be effected and the poly surface will have enough integrity to keep it at bay. Spiders in gear knobs are set in poly, not sure what the comparability of spiders and Polyester are. I would just make sure I would not overwork the areas around the joints though. -
I know this is a bit late but....
why not cover the railings prior to assembly?
Use a vacuum, release film and bleed cloth to really give a nice finish to them.
I spent years working with glass, carbom & kevlar on planes. That polyester resin isn't suited to this if you ask me. If you can grab some Epocast 50A then you'll find that quality stuff that's quick to cure and easy to apply.
Also there's a ratio for glass/resin. If you apply too much resin to the fabric then it become more plastic than GRFP and more likely to shatter. Peel Ply (~type of cloth) will remove excess resin and leave only what's needed.
boring enough for ya?
Try masking off areas with sellotape ask the resin can't adhere to it.
-
@steved said:
Hey Jeff, I was assuming that the joints were done with epoxy and the glassing was done in
poly' is that correct? If that is so, I think if the cleaning is done sufficiently well, the remaining epoxy will be in such small amounts (in the cells of the wood) that the polyester will not be effected and the poly surface will have enough integrity to keep it at bay. Spiders in gear knobs are set in poly, not sure what the comparability of spiders and Polyester are. I would just make sure I would not overwork the areas around the joints though.yeah, you're right -- the joints are epoxy and the glass is poly..
but what's weird is that the epoxy was done prior to the glassing (already hardened etc) and is mostly inside the joint (the mortise is 3/4" deep x 1.5" x 2").. the joint is also a bit loose (around 1/32" gap) due to the way the separated parts needed to be assembled (there had to be a bit of wiggle room in there for everything to slip together properly.. this is why i used epoxy in the first place as it doesn't require super snug joints/clamping for a solid bond whereas wood glue would require that type of fit)
point being, there's only a tiny amount of the epoxy which is being exposed to the poly -- it's the thin line around the railing where it goes into the post and that's what's causing the problems for me.. and that little strip of epoxy is causing the poly to fail up to 1/2" out in all directions
so, i'm very hesitant to put any more polyester near the joints
(edit)-- granted, there was some squeeze out of epoxy during assembly which I scraped off.. I'm sure this is probably the stuff causing problems and it's not spreading outward from those tiny gaps alone.. I imagine if I'd of sanded the epoxy off instead of just scraping up the obvious stuff, I'd have much less of a problem here)
-
@rich o brien said:
I know this is a bit late but....
why not cover the railings prior to assembly?
please go back in time a few days and tell me this !
but yeah, too late now..@unknownuser said:
Use a vacuum, release film and bleed cloth to really give a nice finish to them.
I spent years working with glass, carbom & kevlar on planes. That polyester resin isn't suited to this if you ask me. If you can grab some Epocast 50A then you'll find that quality stuff that's quick to cure and easy to apply.
Also there's a ratio for glass/resin. If you apply too much resin to the fabric then it become more plastic than GRFP and more likely to shatter. Peel Ply (~type of cloth) will remove excess resin and leave only what's needed.
boring enough for ya?
Try masking off areas with sellotape ask the resin can't adhere to it.
i'm pretty sure i didn't put too much resin on.. the plywood soaks it up quick and there are no drips or puddle looking things on the first coat..
i can get the epocast around here but i'm trying to get my supplier to swap my remaining poly (i have an unopened gallon) for some of their epoxy resin.. if they're not into it, i'll look into the epocast more seriously as it's considerable cheaper than the stuff i'm looking at (about $170 for a gallon/hardener + shipping)
-
on a lighter note… check out my 6yr old assistant..
who woulda thought a fur vest & short skirt were such good fiberglassing clothes?
-
@unknownuser said:
on a lighter note… check out my 6yr old assistant..
who woulda thought a fur vest & short skirt were such good fiberglassing clothes?
a ghostly apparition
-
Ah
the masters...
-
lol.. nice
-
@steved said:
I would remove the retarded 'gel' initially, mechanically by scrapping with a Stanley knife blade to remove the polyester/Epoxy mix bulk, and then and then thoroughly clean with GP thinners (the thinners will not effect the thermoset resin, sure you know that though) let it dry and sand the whole thing to give it some tooth. I would then coat it with polyester resin again, sand, re coat, sand, final coat. Not an Industrial Chemist but that's what I would do.
well, in the end (I hope it's the end), I went with this suggestion..
got rid of all the goo.. grinded all around the joints.. layed down another coat of poly..fingers crossed its going to cure properly this time
-
Hey Jeff how did it go?
-
@steved said:
Hey Jeff how did it go?
pretty good.. there are two spots which didn't fully cure but they are tiny.. 1/4" x 1" strips on bare wood..
much better than the mess the first time around (24 joints-- failed cure 1/2" out in all directions leaving pliable fabric)i just wiped the area with acetone and put epoxy there instead..
all in all -- a bit of a nightmare but it's good now..
Advertisement