The Stovebolt Site Forums The Shop Area Paint and Body Shop remove bondo and prepare body question

There is some bondo on the roof of my '57 Suburban, up to maybe 1/4" thick in one spot; the roof is a bit wavy on one side!
The steel is rusting under the bondo (I did not do it, bought it that way!!!), which is partly falling off.
~What is the easiest way to remove all the bondo to get to the steel? I want to be able to do this in my garage (no blasting...); the bondo on the rust comes off easily, but the one on clean steel stick really well and I want it gone!
~What do I use to prep the clean steel before applying the new bondo? I have some Metal Ready, made by POR15, would that work?
Thanks.
PS: if it makes any difference, this is a daily driver which is not perfect, not a show truck.

36 grit on a DA is the way I would take it off. Just say NO to POR-15. Paint-over-rust is what it stands for. I would take off all the rust and spray it with epoxy primer then do the body work, but thats just me. Someone else might have a different way that's better.

I second that ,epoxy primer is the way to go.

I used a 3M rust/stripper wheel. It does almost nothing to the metal but it rips through bondo.

Yeah, use 24 grit discs on a grinder if you want the bondo removed fast. 36 grit is good too. Then go over all the bare steel with 80 grit to get all the rust off. Then wash the bare metal with 3M Enamel Reducer# 3812. Then knock out any dents with hammer and dolly. The wash again with #3812 , then prime with epoxy primer. Do your plastic filler work over the epoxy. Sand the plastic filler smooth.Then use urethane high build primer over the plastic work.

What truckernix said, remove the bondo without removing metal. That area maybe weaker do to the previous bodywork, so easy does it. Just make sure the metal surface is clean before you spread any body filler. Body filler that won't feather edge is a sign of poor prep, and or "bad" filler. After sanding out the body filler, then prep for primer. This is where I suggest you "read" the product labels and follow the instructions. With paint jobs costing in the $thousands you don't want to take any short cuts. The paint supplier will explain thier products, and in most cases try to over sell, so do your homework. Last but not least, depending on the size of the area your working, the roof can be kind of tricky, don't stretch or warp the metal. If you don't have bodywork experience, seek advise from a professional, most of them like to share thier wisdom.

I've heated bondo up with a propane torch before to take off large thick pieces.

Second on truckernix, I have used that very successful on removing large amounts of bondo, plus it roughs up the metal so that primer will really stick well.

I agree with the sander but POR 'Metal ready' is not a paint.
When used properly it etches the surface metal and leaves an almost nickel plated look. It also provides a good key for paint.
I'm not entirely sure how compatible it would be with non POR products though.....

Too each his own, but for the price of the POR-15 and all it's prep product you can buy alot of epoxy prime, and I know how to use it. POR has it's place (I just haven't found it). If it works for you, then that's what I would use. Por-15 does flow out very well you can paint it with a brush and not leave markes, But you have to topcoat it, then you will have brush markes in your paint. just be sure you have a good coat of surface rust before you paint it, I just have a hard time painting over rust. If it were UV safe I would use it some. JMO

57blevins...I agree, I used POR products extensively on my project.I would never paint over heavy rust myself.
I used 'Metal Ready' on good clean prepared steel (no rust) and it left a nice finish,ready for paint.
In an ideal world I would have had everything blasted or dipped,but financial,time and logistical constraints didn't allow this.

I just wondered about 'Metal Readys' compatibility with other forms of paint/primers.
I was lucky as my truck came from So-Cal,therefor rust wasn't a big problem.
The UV sensitivity is a pain,but I used it in areas that won't see the sun.(I live in Scotland after all! )

Heck,I could probably paint my WHOLE truck!
(wave...sorry for hi-jacking the thread!)

Each to his own as they say!

We painted the frame of my sons truck with POR-15. It looked great, so we didn't top coat it, the sun don't shine on the frame (right?). It still faded BAD within one year it looked like crap.

A wire knot wheel works good on bondo too, it doesn't load up like a sanding disc does. The 3m and Norton strip discs work great too.

Any time you use something like POR-15, consider how compatible with whatever you put over it that it will be. I think POR has its place but I wouldn't put it under real paint. Its good for wheelbarrows and trailer frames and fender wells where you just want to keep it from rusting any more. It takes more labor to top coat POR15 with primer and paint than it does just to strip the rust off the metal and prime it conventionally. Removed rust won't rust again as long as it has paint on top of it.

quick question, when using epoxy primer, must you have everything down to bare metal, (just starting my new project, never a body and paint guy)
thanks for any info