Notes on Using Epoxy Resins for High Power Rocketry

Extra Time Epoxy

At One Way Rocketry, we insist on keeping a longer-working-time epoxy on hand, so we don’t botch a step trying to get away with 5 minute epoxy when we really need 7 minutes to pull of the operation.

“Extra Time” in epoxy speak usually gets you from five minutes working time to around 20-30 minutes working time. 20 minutes should honestly be enough time to glue anything important, with time left over. To achieve longer epoxy working times requires more chemicals to slow the process. A 60 minute epoxy will likely be yellowish due to the slowing agent added.

A benefit of the slower curing time of these epoxies is a smoother result having more time for gravity to make the epoxy more level before it sets. A negative might be the inevitable thumb-print you will make checking to see if it is dry yet. It is also increasingly more difficult to find slow-cure epoxy. It seems patience might be required.

We found LOCTITE® Epoxy Extra Time to be a great slow-set epoxy. This can be very important when installing fins, or if you double-check a joint and find it was set wrong ten minutes ago; there’s still time to fix things. Trust us, you want it around and you want to consider using it each time.

The strengths of Loctite’s Extra Time Epoxy are obviously its long working time, and its convenient delivery system by way of dual syringes and storage cap. Negatives: price-per-ounce is a bit high, and the agent to slow the curing might be the cause of the yellow tint which looks like pre-aged beige plastic. Probably neutral is the strength rating of 3000; not the lowest score for an epoxy, like the cheapest you could buy at 2000 psi, but not very high like J-B Weld at more than 5000 psi.