total cure time

Posted by LeeG on Dec 17, 2005

Given that the time for a COMPLETE cure for very slow epoxies is upwards of seven or more days with sanding often occuring before then I don't think this an area where one can rely on data and applications in another context applied to this one. I would think that a medical device made of cured epoxy would go through a very strict protocol of fabrication before it goes in a body. Aerosolized epoxy dust in backyard/garage boatbuilding is not going through the same protocol.

I'm comparing the square footage of aersolized epoxy (some of which isn't fully cured)particles compared to a fully cured and "inert" medical device. Once it's in, it's in, the cured and the uncured. In backyard building there's enough cutting of corners by folks unfamiliar with epoxy that a blanket statement "completely cured epoxy is harmless" is risky given the ignorance as to when epoxy IS completely cured. Mullman being a good example.

Is "completely cured" in 24hrs? If I can remove clamps in 24hrs maybe 24hrs at room temps is 'completely cured'. Of course if a person reads the spec sheets from the epoxy manufacturer you'll see times much longer than 24hrs for a "complete cure" with slow epoxies.

The problem is some people are more sensitive than others and they don't have meters gauging that sensitivity BEFORE the reaction occurs. I'm not a medical person but having read about people getting reactions from a tiny amount of some food particle, or in Mullmans case totally sensitized so that a drop on fingers caused his eyes to swell up it would make me think reducing exposure AT THE SOURCE with a shop vac makes as much sense as gloves for people who already notice some change in their body when using epoxy. For me a reddening of the eyes and slight malaise after glassing is a clue I'm sensitive to some degree even though I don't let the wet stuff touch me. Ten years ago I sanded 'cured' epoxy with a 1/4sheet sander and by hand creating clouds of dust covering the backyard bushes. Now I won't sand without a shop vac attached to a ROS. If I knew then what I know now I would have spent some of the $$$ on sheet sandpaper and got a long hose to connect to the shop vac and bought a ROS.

Bringing epoxy dust into the house, into the washing machine, etc. may be less of a concern with COMPLETELY CURED epoxy but if there's a percentage on each particle that isn't,,then those particles are all over the person continuing the exposure. Some of my wariness about cured epoxy being benign is from a fiberglass kayakbuilding book that mentioned some people being so sensitized to epoxy that they couldn't even paddle in a kayak made of an epoxy/glass laminate. Maybe that's a consequence of backyard building and epoxies available 30yrs ago. I know some people who can't be in the same room or building where epoxy work in going on. Like John mentions it looks like the odds of folks getting reactions are somewhere under 1% but repeated contact moves some .01%ers into 1%ers and 1% into 10% on their fourth, fifth or sixth kayak. It would be a shame to develop an education just in time to not be able to build "the boat" due to sensitization. Multiple boat building (it's hard to stop with one) WHILE learning the difference between "cured enough to.." and "completely cured as to be inert" can provide some folks with more exposure than they need in order to build "just one more".

Removing epoxy or wood dust at the source,,and moving it outside to a shop vac will cost upwards of $75 for a 25 hose. Not a bad investment in ones health.

In Response to: Re: Epoxy dust is very ba by Mark Camp on Dec 16, 2005