This is a 28-day salt fog test. I used the Bondo brand body filler on bare metal , over epoxy zinc phosphate primer , and the aluminum pigmented moisture cure urethane primer. The primer I used was Restoration Shop epoxy and the urethane primer is Mastercoat. Panel number one epoxy three coats over a miniscule amount of rust. Panel number Two urethane down first Bondo, urethane over it. Panel number 3, epoxy down first, filler epoxy over it three coats. Panel number four Bondo over bare metal epoxy over it . panel number 5 three coats of epoxy primer. Panel number 6 Master coat three coats.
Based on the photos, it's hard to tell which performed the best...what is your conclusion seeing them first hand and knowing exactly what you started with?
Dad used lead back in the day but when Bondo came out he embraced it and enjoyed working with it it far better...
Sorry for the confusion this was going to be a video but I've got tired. Number one is the zinc phosphate epoxy three coats over a slight bit of flash rust. Not great. Number two Master coat down first another coat of Master coat over the Bondo. this one seemed to work pretty decent number three epoxy primer down first Bondo epoxy over it not too bad. Number 5 three coats of epoxy over 80 grit . Not great. Panel number 6, 3 coats mastercoat no deterioration or creepage along the edge
Panel number 3 had two coats of epoxy primer, Bondo was applied over it followed by another coat of epoxy primer over the bando. Number four is Bondo applied over 80 grit panel and three coats of epoxy primer over it Panel number 5 is three coats of epoxy primer , no body filler over a q panel ground with 80 grit bare metal
Neither one looks great, but I would say #4 bondo first covered with 3 layers of epoxy came out better than #3 two layers of epoxy first then the bondo with a 3rd coat of epoxy over the bond. But the difference is slight.
Panel number 4 had a large blister in the middle Number two and number six survived the test. These panels will not be rinsed off they will continue to rust even though they're not in the tank any longer . I will post a picture in a month. The moral of the story as soon as you can rinse the salt off, the better off you are.
Thanks for the test the bottom line is that you have to get ride of the rust first then seal it when done with the repair remember all plastic fill is poures. Repair,prime,seal,topcoat.
What differing characteristics are there between brands of body filler? I’m not challenging your opinion, just asking. I would have thought the body filler would react about the same, no matter what brand. Is it better quality resins in the higher end brand fillers, making it not as porous? Fill me in. (No pun intended)
All of my cars have been done basically like # 4 and seemed to have held up pretty well over the years. I do the metal work my buddy does the filler on bare metal then epoxy then slick sand spray polyester. But he always uses Evercoat Gold filler.
Sandability, edge feathering, pinholes/air bubbles, how it takes primer. Lots of small variables. I prefer Evercoat products but have friends that really like Upol as well.
I use rage gold on my projects. The gallon of Bondo I used on my van. Here's the beauty of it once I put down My primer and then any kind of filler and my primer over it doesn't go anywhere . It's sealed Solvent proof , pin holes are filled in and no shrinkage. if anyone would like to send me a panel with your favorite combo I'd be happy to put it in my tank and test for you
We salt spray test all our fillers and they will last from a range of about 200 hours to over 500 hours so there can be a pretty marked difference in how they react.
I have used about every flavor of Rage that has been made and liked them all fairly well. I switched to 3M for a stretch, trying the select, platinum plus, etc, but went back to Rage recently. My question was not about the physical characteristics that make us like/dislike different brands. I was asking what would make one brand of filler less/more susceptible to corrosion than another.
I used Bondo brand on our '41 in '95. never lifted or had any problems. only time it cracked was when we hit a deer and demolished the front end.
https://images.tcpglobal.com/sds-sheets/CUS/KUS-EPOXY-PRIMER_TDS.pdf Well, this epoxy looks to be better than most. According to the tech sheet info it is lead and chromate free, it has a higher film build (1.5 mils per coat) and shorter cure time than some others (like PPG DP primer) and it isn't recommended for use in cold shop conditions. If you do another test, lay a water wet rag and a thinner wet rag on the cured primer and see if it absorbs either. I personally seldom use epoxy primer, if I do it's usually as a sealer/tie coat for automotive repair. I used to use some sikkens epoxy and Evercoat had a really good high build epoxy for a short time, but they are both gone. Thanks for posting the info and the test.
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