system 3 epoxy instructions

[Andy Maldoror]

got some system 3 epoxy with hardener #2.

when it says 30 minute gel time...does that mean you apply it after it gels up in around 30 minutes? or do you apply it immediately?
tack free time is 4-6 hours, does that mean it's fully set in 4-6 hours?

[Gene Howe]

Apply immediatly after stirring.
Fully cured in 24 hrs.
If you need thicker epoxy, Sys. 3 sells several different types.

[Andy Maldoror]

where do you get the 24 hours?
is that specific to wood?

[matt tennessen]

24 hours is a safe assumption for "cured enough to move on to your next step." What is the application you're using this for? Recently (today) I've used that epoxy to fill/set knots/nail holes/worm holes in some reclaimed oak joists. It sets up tack-free in less time but I can sand it after 24 hrs.

[Andy Maldoror]

gluing dowels that hold together a wood frame for a small 5 sided plexi display case.
4 posts with two dowel holes at bottom and top into which cross members fit with dowels.
the dowels insert about a 1/4" into dowel holes, which meet each other inside the post at a right angle, so there is a little empty space in each corner.
make any sense? can't get to camera right now.

[matt tennessen]

Apologies, I'm not sure I'm picturing it correctly. Are you saying that you're using the epoxy to glue a dowel joint? Or are you using it, aesthetically, to fill a gap in the corners? Either way, if it you let it cure overnight you'll be fine. Depending on how much you feel you'll stress the joint, you're probably fine to move forward in a few hours. If you have to use a large amount of it, it may be gummy before full cure so be aware if you plan on wrestling with your case.

[Alan Schwabacher]

Epoxy hardens gradually, and the rate depends on temperature. It starts out as liquid that thickens until it becomes a gel (at the gel time) but continues to harden after that. The "tack free time" is how long it takes to no longer be sticky on the surface. It will continue to get stronger long after it is hard and dry, reaching maximum strength after as much as a week. That does not mean it's not pretty strong long before that. You can buy many types of epoxy with dramatically different cure times and temperatures required for cure.

The system three epoxy book does a good job of explaining.