Frothy epoxy- like honeycombe?

[hansp77]

Has anyone had epoxy froth up before?
Today while I was filling a hole with epoxy- west system mixed with microspheres and glue mix and glass strands- the deepest of the holes that I filled frothed right up about 2.5" and set really quickly. There could have been some sadust in there, or there could have been a tiny bit of moisture in the fiberglass, or alternativelly it could have reacted with some residue from the blue 7 wood rot killer that I treated the wood with (copper-fluron-boron)..

The strange thing was that this hole did it, but the other one I filled at the same time, with the same mix, and with the same impurities, did not.

While I dug the frothed up lump out, because I wasn't confident it would be strong enough, after a while when it finally set rock hard it seemed to be really strong, and light, and could actually be really usefull for certain things if the reaction could be repeated.

Anyone know what happened here?

Hans.

[marshmat]

The lump that frothed could have contained a pocket of liquid with the wrong catalyst ratio, ie. a lump that didn't get fully mixed. If there was too much hardener in that glob, it could have got really hot really quickly, perhaps even turning some of the moisture to vapour in the process. Epoxy doesn't react with very much and I doubt that even the rot killer would do that to it.

[wdnboatbuilder]

IS it getting to hot? and have had that happen when thicking with wood flour.
The mixture when kicking off and is really hot like setting in the sun has happened to me.

[yokebutt]

Try it with a proper blowing agent instead of heat. I tried floating a similar question to the local epoxy maker a while back, but he thought syntactic epoxy would be stronger for a given density. ("Syntactic" just means resin mixed with lightweight filler powder)

Yoke.

[JR-Shine]

I have seen it a couple times when a concentrated mass sits in a pot - on a hot day.

[hansp77]

Just to follow up,
today it started again,
in the oposite corner of where it happened last time.
but this time I had added a heat gun into the mix.

I think it must be a heat thing, probably also with a moisture thing, though this time I don't know where the moisture could have come from..
I chose not to dig it out this time, as it did not foam too much.

I think maybe that it has to do with the depth of the holes that I have been filling. The deeper the hotter, Also with the mix that I have been using.

Epoxy, powder (microspheres and or glue additive) and fiberglass.

Today I began using chopped up fiberglass. That is fiberglass matting that I had chopped up with sizzors to less than 10mm pieces.

While it behaved in a similar consistency as normal filler epoxy, the glass strands in it would hold it together and stop it from just completly drooping and running away.

This mix has been amazing in allowing me to free form things.

I am zombie.

too tired from continuous twelve hour days, at least.

tomorrow we glue in and seal the new deck and cabing roof.

No more goddam tarps.

gooodniightt.

more to follow in my other thread soon.

too tired to make sense.
Hans.

[JR-Shine]

A concentrated mass of thickened epoxy will generate a high amount of “exotherm”. You should use a slow hardener. Also you might have to do it in increments to avoid the mass. There are fillers you can use to help with the heat buildup – I have not used it, but I’m told Aluminum Oxide helps