Polyester Resin to Bondo Ratio

Justin Swain

This question might be answered elsewhere, but I'm doing a mold much like David Monzingo in the Rod Puppetry course. My question is: What is a good ratio to mix Bondo Body Filler with Polyester resin to get the ideal consistency for a first coat?

Chris Ellerby

Hi Justin,

I don't know the best ratio, but I can pass your question along to the team.

Thanks,

/Chris

Justin Swain

Thanks Chris!

I'm guessing you just mix both until you get the desired consistency before adding the catalysts, but i just want to make sure before wasting time and materials.

Matt Winston

Hey @Justin Swain - Here's some thoughts on ideal consistency of Bondo Resin from David Monzingo:

"I'm sure that there are more skilled mold makers who have an exact ratio, but I don't. When I make bondo resin, I mix it by eye. You are looking for a consistency that will easily spread over the surface and detail of the piece being molded. Not too thick so that it can't spread easily, but not too runny that it won't stay where you are applying it. Part of the reason I don't have an EXACT ratio is that different batches of automotive filler (bondo) have different consistencies themselves... some are thicker than others so having a fixed ratio won't always produce the results you want. I'm trying to think of an analogue that I can compare a good bondo/resin mixture to... maybe extra creamy peanut butter? I hope that helps."

Justin Swain

Thanks Matt! And tell David thanks as well.
I kinda figured that would be the case.... Worked great!!

Matt Winston

Excellent to hear, @Justin Swain! I'll pass along your thanks to David.