I was wrong (and a question)

about a year ago there was a conversation about bondo and putting it on bare metal or over primer. Well My father owned a body shop for years and we always put Bondo on bare metal only. well back in those days we only had laquer primer, and even on the Bondo cans it says to apply on bare metal. Now with the new primers you do put bondo over primer, but only if using the newer epoxy primers, not over laquer primer.

Now my question do you do any sanding before putting the bondo on? It seems there isn't enough "tooth" I'm worried the primer is too smooth to hold the bondo.

Any help is appreciated.

Dave

 

I usually at least go 80 grit and sand er up pretty good. Mostly when doing bondo I use 36 grit to give it some real good tooth.
Dan

 

I DONT KNOW MUCH ABOUT IT MYSELF BUT I WOULD SAY RAYZORSHARP DOES, CONSIDERING HE MANAGES A FORD/LINCON/MERC. BODY SHOP... JUST MY

 

I'm confused if you use 36 grit you will gouge the primer off also.

 

What's confusing? You are covering up the primer anyway. I am not a profesionel but that would be my asumption. Why spend the time removing the primer if it doesn't matter or spend the time detailing the prep for the ultimate finish, I guess.

 

im a bare metal guy myself when it comes to bondo.. and yah i like 36 grit to rough up the metal. but im just amatuer. just my 2 cents

 

Hey Blu, I understand what you are saying but the "New" idea is that you seal the metal with primer so the bondo doesn't come in contact with it. I was a bare metal guy also and took that position strongly in the debate last year about metal or primer but now have edumacated myself as to why the change with the new primers and all but was trying to better understand the workflow.

Guess my self edumacation hasn't been all that complete.

 

Hmmm... Intresting. What's wrong with the bondo contacting the metal? By the time you finish the paint job isn't it sealed? I say getr done and show it off. I guess being that I don't have ALL the time in the world to spend on EVERY detail, I will skip some things as long as it isn't obvious or going to cause me great griefs. I'm going to let someone else do that part anyway, so... Hope I get a warranty

 

I never use Bondo. Bondo makes a body filler but I prefer Evercoat Gold or something similar. It may cost a little more but once you use it you would never go back to Bondo brand filler. So much easier to sand and apply. Just my

 

I asked some of these questions not long ago on one of my projects and also at work. Assuming the metal was properly prepared before the epoxy or etching primer was applied.... body filler (bondo is a brand name) can be applied right on top. Although, the epoxy or etching primer needs to be scuffed (I use 80 grit) if the primer is more than a few days old. The adhesion of some of the epoxy primers these days is pretty amazing - especially if it is baked. I've seen epoxy primed metal hemmed 180 degrees on itself and it doesnt crack or peel.

Cleaver

PS- EDIT most fillers should not be applied more than about 1/8" thickness. It will crack because the polyester will expand/contract at a different rate than the steel and will eventually crack.

 

Thanks everyone. I was so set in my ways (Plastic on bare metal only) I'm having a hard time getting my mind around this.

 

I still don't seem to have an answer from someone who does Bondo over primer. And yes I say Bondo because that is what I am using. I know it's a brand name. Won't the bondo pop off from not having enough "tooth" if it is put oiver primer?

Someone who does this please walk me through this.

Thanks