[swoodard23]

No matter how much I sand the bondo I cannot get it perfectly smoothe. Will 3 layers of primer cover up say 60 grit sandpaper swirls?
Thanks,
Scott

[BondoKing]

First off you could use 60 # for the first pass on working down the filler, then you should continue working your way up in grit.. Then once you feel like it is "right" apply a skim coat of glaze over the whole repair area again and work it slightly with 80# then some 180# and you can stop their or go back with 220/320 then you will be ready for primer... You will never have it looking right going about it the way you are now I think...

What is the process you are using right now? Just want to see what you are doing so we can help correct mistakes

Matthew

P.S. Jclark is a stellar bodyman, you can PM him for any details you need if you dont want to post in the open

[swoodard23]

I am just applying bondo, sanding down to nearly flat with 60 grit, then sanding with 100grit, and ending with 150 grit. The problem is there are some small spots where the filler must have had an air pocket that I can't sand out. Also, even when I sand down to 150 grit, when I spray some paint on to see the results I can easily tell where the bondo starts. It is like the filler is porous or something. I have tried thinning the filler with some resin which seemed to help a little. Also, what is this glazing you speak of?
Thanks,
Scott

[rrmccabe]

Scott,

You are not supposed to get filler smooth enough to paint. That is what fill primer is for. I am not talking spray can primer either. A decent primer designed for fill.

Bondo is not going to feather well. You need to get it close with sand paper and then spray fill primer over the top and block sand it.

I am not sure what you mean about air pockets but if you are talking about a flatter look that is grainy, that is normal. Don't try to thin your filler with resin or you are going to end up with a sticky mess. Mix it per directions. It sounds like you are trying to do more with it than it was designed to do.

You said swirls in the filler not covering. So I am assuming you are using a DA sander? Using a DA I normally finish with 80 grit and sometimes 120 depending on what I am doing. (this is before primer)

To me it sounds like you are missing the magical step of fill primer. Something you cant skip ! No matter how good of job you do, if you paint over bondo you will see every imperfection and feathered edge period.

Rich

[BondoKing]

read these next

http://www.a2zautoforums.com/showthread.php?t=936
http://www.hotrodders.com/t44006.html

I think this will get you on the correct path bro

[staircasesurfer]

if you have "air pockets" or pinholes use a 2 part glazing putty, that will do the trick, with this type of putty start with 80 NO ROUGHER then get down to 180-220 grit, then use a filling primer over that (a good 2k primer NO Spray Bombs) hope this helps