Body filler over 2k primer

[American Locomotive]

Working on a Toyota restoration project. We first laid down epoxy, put in some body filler to fix little spots, and then coated it with 2K high build primer. Well things got in the way and the project has been sitting for many months, probably like 7-8 months. I am aware I will have to scuff and clean the 2K primer really well before coating it with more epoxy because of the sitting time.

But that's not the main issue. The problem is on one of the fenders, I noticed that we didn't blend a small spot of body filler very well, and it's definitely pretty noticeable. I don't think the 2K primer applied heavy enough to block it out either. I think it's going to need a very thin coat of filler in this area to clean it up. However, a few sources I'm reading online are saying that 2K takes a very long time to fully cure, and it's not a good idea to put filler over 2K.

Do you think given the very long time my panels have been sitting, that the 2K should be sufficiently cured that a quarter-sized bit of body filler should be okay to apply if I scuff up the 2K? I'd hate to take this panel back down to metal (like literally, I will hate the panel).

 

[zmotorsports]

If your 2k primer has sat for several months as you mentioned you should be fine. I think they state not to apply filler over the 2k primer due to usually a lesser time that the primer will sit before blocking and recoating, such is next day.

As for applying some filler over the top of a 2k primer, I would hit it with some 80-grit which will provide the necessary "tooth" for good mechanical adhesion of the filler. Even better yet, would be to use some glazing filler, which is basically just thinner body filler. I actually do this when I find small pinholes or very small defects after the high build primer and is quite common in the industry. The key is to use a skim coat and not get a large buildup of filler. Although, that is paramount when using filler regardless of whether it is under or over primer surfacer. I like that you used epoxy over the bare steel, good move and one I don't see often enough.

 

[jmdirk]

I'm sure you'll be fine. There's a whole school of thought out there that 2K goes down first and the body work and filler is done after.