What Is The Best Bondo To Use Over Body Solder??

[Chuck Kuntz]

I have a door that has some previous repair with body solder. What type of bondo is best to use over this repair. We always used duraglas years ago. Thanks for any info.
Chuck

[Ardun]

As a collision repair shop owner, we never concerned ourselves with a brand that adhered well to lead. Just make sure all is clean. Today’s “bondo” even adheres to paint.

[deuce_roadster]

I use "All Metal" first, it is harder to sand but stronger then the polyester filler but any brand would do I am sure. I always remove all the lead I can first with a torch and wire brush.

[Bored&Stroked]

If it was mine, I would remove the lead before putting body filler on it. This is especially true if you see any pinholes or other issues with the lead work - or prior adhesion problems with primer/paint over it. If the lead looks to be really sound, then make sure you put some good scuff marks in it to help the body filler adhere to it. There are MANY super quality body fillers out there today - they sand much easier than ever before and really do a nice job. Some even have rust preventative and etching chemicals in them. I would talk to my local professional body/paint supply house - they'll recommend a product they've had good luck with.

I know a lot of guys that have used RAGE Gold (by Evercoat) and have been very pleased with the results.

[Karl Wescott]

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Most plastic body fillers "aka bondo" use a polyester base, the same class of chemicals used to make fiberglass resin. The high quality ones may use a resin base with better adhesion than others but they are still polyester.


Body solder "aka lead" is best applied to an acid etched surface and with a wax lubricated wood paddle. If everything is CLEAN and neutralized the "bondo" will work well. If there is still acid present it will inhibit the cure of the "bondo" and cause failure. If there is wax residue remaining, well it acts a release agent to allow the "bondo" to fall off.


Polyesters are also slightly pervious to moisture, so any pinholes in the underlying metal or exposure from chipped paint can allow the "bondo" to absorb moisture from the air and cause rust, and adhesion failure, under the body filler. Coating the steel/lead base with a "sealer primer" before "bondo" will help this.


Bottom line. CLEAN, no acid residue, no pinholes, you are good to go.