Bondo question

[ghostkode]

Hey guys I was wondering if you use any kind of metal prep before applying Bondo straight to metal.

 

[70Duster440]

Nice clean metal with a course scratch is your best bet. Some apply it over primer but the technique is debatable.

 

[clifftt]

That's how we do it in our shop.

 

[BillGrissom]

Most I have seen on TV apply it straight to bare, sanded metal. I always apply an etching/rust-converting primer first since I have seen many Bondo'ed spots rust thru, but maybe the gomers applied it right over rust. Read-up if Bondo Hair or other fiberglass type materials since I have read that moisture can travel thru the fiberglass, so a primer seems prudent.

 

[chryslerfat]

I hit it with 50 grit and a 5 inch disc to give it something to grab to. I have seen it crack and peel off primer.

 

[69moparmuscle!]

Use good bondo and you wont have a problem bonding to bare metal in my experience. recommend RAGE.

 

[kevindahle]

It is Not good to put it over etch primer, bare metal or epoxy primer only, and even with epoxy it can't be applied right away. if I am stripping a large areas or multi-panels i will epoxy the bare metal asap so I don't have to worry about the exposed metal but if I am working on small areas I just apply the filler to the clean sanded bare metal.

 

[71beater]

Grind with 24 or 36 grit.

 

[Woods74]

220 scuff works also, the truth is, you should have a minimum amount, 1/16th", that it doesn't matter.

 

[1968FormulaS340]

Im a professional Collision Repair Technician. You should never apply plastic body filler to a 220 scratch on bare metal.

It doesn't provide for the necessary mechanical adhesion.

80 grit is the minimum I would recommend.

Normally I do my metal work then score the filler area with 40 or 50 grit before applying body filler..