How to keep Bondo Plyable

[kahlid74]

For the Bondo experts, how do you keep your Bondo plyable for longer?  I've found that in situations where I use the recomended3/4" circle and 3" line i'm only about half way though the bondo before it begins to harden.  Should I use less of either part of should I use less of both?

[compute]

I ended up mixing smaller quanitities to avoid this problem.  It sucks having to mix a batch every 5 minutes, but I think the results are worth it.

[lilshawn]

using not enough hardener can cause the filler to take forever to set up...or even not at all. (stays sticky and soft.)

mixing and applying in the cold then bringing it in to harden can help delay the setup. (works for fiberglass resin too)

smaller batches is the ultimate key here.

[DNA Dan]

Ditto what Shawn said. If you add less hardener you might not fully polymerize it. You could back off on the hardener a bit to give you more MINUTES, but if it takes longer than 30 minutes to polymerize, I would question it's integrity. Only make up what you can reasonably work with until it hardens.

[VanillaGorilla]

Working in a cold environment will dramatically extend the working time of filler. Go a bit light with the hardener too. You're never going to get longer than 20-30 minutes though, unless you added something like a paint retarding agent, and then you could have shrinkage issues. No one likes shrinkage

[ChadTower]

Keep in mind that Bondo also sticks to Bondo really well.  Multiple layers on a large spot are normal.