May 27, 2010

Epoxy work in the heat

A technical post from Evan

I use epoxy with a medium hardener.  This works well in BC but not so good in Mexico. 

According to the supplier, a 100 gram volume will gel (start to thicken fast) in 35 minutes, at 24°C (~ 9AM temperatures around here).  I've been making up batches of about 200 g.  Then I add fillers.  Both will make the epoxy cure faster.  Somewhere in the neighborhood of 10 minute.

You know the epoxy is starting to go when the stuff coming out of the mixing tub gets runnier (as it heats up it gets less viscous).  Then it starts to get REALLY REALLY HOT.  Like burn your fingers through latex gloves hot.  Like strong language hot.  So I start to panic and slather it on faster and faster, so as to not waste the expensive goo.  And I burn myself more.  Then I run into the cockpit and put the now literally smoking tub of epoxy outside to fume and vent.

Thankfully today I finished the last epoxy work for the starboard water tank.  Whew and yay!

Gotta get some slower hardener and a bit more resin on our trip back to Canada/US.  I buy my epoxy from  It's lots cheaper than West system and offers a better mix ratio (2:1).  Less chance of mixing errors that way.  Good material properties and no amine blush that West always seems to get.  I've used about 20 gallons of it on our boat building project and recommend it.  Disclaimer:  I sell some of the boat plans at but don't get anything for mentioning their products!

1 comment:

Seven C's said...

I know that feeling of when it starts to go off!
We have been using Max Bond Low Viscosity epoxy from Polymer Composites. A 2 gallon kit usually runs around $90USD (that includes shipping). It is a nice slow set and even when it goes off, it doesn't have the super fast, smoking hot, melt the cup, burn the fingers heat.
Much nicer for interior use! We have used a lot of it and I am happy with it. I know of a number of others who have used it and are very pleased with it.