So, bare metal, filler, epoxy, high fill primer 2k and single pack acrylic black misted guide coat.

Lightly sanding the surface removes the guide coat and primer evenly, possibly i did not need to put the guide coat on the last high fill prime.

This made me think is it okay to leave remnants of guide coats under the finish coat, being that the guide coat is an acrylic single pack misted out of a can and the finish coat is a 2k

Steve

There shouldn't be remnants of guide coat.

The purpose of guide coat is to show imperfections in the surface. You block sand until the guide goat is gone.

I highly suggest using guide coat on the final wet sanding step as well.

Cool cool.

So if you have a low spot as identified with your guide coat, and hit steel when sanding, then you have to put more build primer on, however, does the guide coat need to be removed in the low areas before applying said primer again.

Steve

2K primer needs to be sanded before covering with anything, so
any low areas showing guide means it hasn't been sanded and needs to be.
You can use a much more aggressive sanding grit since more primer is
going on, that'll make it a little easier.

Makes sense, what do you call and aggressive sanding grit for primer coat

Steve

If you have lots of areas over the entire panel, then a polyester primer like Slicksand or Featherfill is the best approach.
It is like skimming the entire panel with filler only much easier.

Generally your initial blocking is done with a coarse grit to get everything straight. If the panel is in decent shape something like 150 grit will work.

This is a used quarter panel that needed a lot of work. It was sprayed with 2 coats of black epoxy and then block sanded with 80 grit to reveal how bad things were.


Two coats of poly primer and some block sanding:

Doors were not great

'68 Coronet R/T wrote:This is a used quarter panel that needed a lot of work. It was sprayed with 2 coats of black epoxy and then block sanded with 80 grit to reveal how bad things were

To clarify, bare steel rough looking quarter, straight into an epoxy primer then block sand 80grit to reveal all the low spots, then filler onto those low spots?, are you roughing the area up and applying filler or taking those areas back to steel and then filler

Thanks

Steve

With a quality epoxy primer, you do not need to sand before applying filler IF within the re-coat window (up to 7 days on the brand I use).

I block sand the filler with 80 grit until it is level with the surrounding area, then another skim coat using a bit of Evercoat Plastic Honey in the filler that extends over the sanding scratches. From there you can block the filler with 180 grit.

The trick to block sanding is not to press too hard on the block and change your paper as soon as it quits cutting. Pressing hard can flex the panel thus removing the filler and not straightening the panel.

simso wrote:Makes sense, what do you call and aggressive sanding grit for primer coat

Steve

I use 150 to 220 usually.