The Stovebolt Site Forums The Shop Area Paint and Body Shop filler over urathane primer surfacer

After I media blasted my cab and front end parts I hit it with phos acid cleaned with wax and grease remover and primed with epoxy then with in the window went over that with urithane primer surfacer. I then block to find the low spots with 80 grit. I ended up sanding most of the urathane off and skim coated with filler over the doors and fenders. I have heard that filler over urathane is ok from some and not from others. What do you guy's say and why. I will probable just epoxy the bed and fill over that after scuffing it up, but I wondering what the truth is about this. Thanks.

You are fine it will stick, Where people have problem with plastic sticking, is when it is misused, over rust, to thick, not sanding first, and so on...

Applying filler over any coating is not normally recommended because if the bond between the coating and metal fails everything on top of the coating will come off. If the pre primer prep was good the primer should stick. If the primer is prepped well the filler should stick to it. I prefer to put filler on bare metal then shoot the primer. What do the filler instructions say?

Well, I agree with you fellers. It's excatly as Tiny suggests. As long as you prep your surface before, no problem, and that goes for the primer, etc, as well. Painting is mostly prep work.

Hi guys. There's a real interesting article on this very subject on Autobodystore.com. Here's the link to the tests they did regarding epoxy vs bare metal under filler.

http://autobodystore.com/filler_&_epoxy.shtml

They have a lot of info on their site as well as a forum to ask questions. Hope this is useful

pat

That test was very intresting. But to the extreme a hit that hard on your truck and your going to be doing body work anyway. It stands to resune that the less different products on there, the less that can go wrong. I like the epoxy primer where I've done rust repair. It helps seal it up. If you leave a little pin hole in a weld and water can get in behind the mud it will rust back out fast. we've all seen those little bubbles come up in a fairly new paint job. I like to use a product called all metal as a fist coat (front and back side) any where that Ive welded. It don't soak up water like bondo does.

Thats why I like lead when any welding is done it flows into all the nooks and cranys if there are any from welding.
Some times all you need is some spot putty.
Fish04
Don

Don
Where do you get lead and safty requirements?

Thanks
Brad

Don
Where do you get lead and safty requirements?

Thanks
Brad

Thanks you. I think I will keep on going as planned. I had to repair a high spot using a hammer and dolly and after wacking it for the repair all stuck well, I sanded back to metal any way but it gave me a good chance to judge my adhetion. The autobodystore article was interesting however he did state that he did not ruff up his epoxy prior to filler but only put the filler on during the recoat window. My paint supplier said to definitly hit with 80 grit prior to filler even if in the recoat window. Again thanks for your input.

Ive only used epoxy primers a few times, mostly as a sealer primer or on fiberglass, but I DO use filler over urethane primer occasionaly ( PPG K36) with no problems, most newer fillers recoomend a good sanding with 80 etc, the one no no is to apply it over etching/acid primers it WILL pop off then( just did a redo job cuz of that!)