Sanding and sealer

[garnet]

I'm just finishing up with the SlickSand and have a few questions:

1. What the stages of grit should I use on the SlickSand, I've sanded it to 180 and read to finish with 400 grit. Should I use something in between that or can I go straight to 400?

2. Do I need to use both a sealer and a 2k primer? Not being a pro every coat of paint creates the possibility of runs or orange peal so I'd prefer to put down as few as possible. Is it okay to paint colour coat over the sealer?

3. Should the sealer be sanded? I'm guessing there might be some orange peal and so I'll likely want to, any reason not to? Am I correct in starting with 400 grit and then going to 600 grit?

Thank you!

[JCCLARK]

At 180 grit I'd stop and put a couple coats of epoxy primer over that.
The epoxy works as a great sealer coat and will maximize adhesion so
you'll get fewer rock chips. It'll fill the 180 scratches too.
Guide coat the epoxy and wet sand it with 400 till all scratches are gone
and it'll be ready for paint.
Let the epoxy cure a couple days first and it'll sand much easier.
2K primers (urethane) are only needed when you need more filling,
if you don't need the high build of a 2K, don't add more thickness
by useing it. If your Slicksand isn't blocked straight enough then use
a 2K over that. You don't really need a sealer after 2K, if it's sanded and
clean you can paint right over it. I never seal over 2K.

[DARKPT]

I did what JC did, except that I tried to get to 400 grit with just one coat of epoxy primer. Make sure you apply two coats like JC said. The primer sprays a lot easier than SlickSand!


Dan

[garnet]

Thanks very much. It can get confusing, the guy that sells the paint advised that the primer/sealer goes down first, then the Slicksand and that the basecoat goes right on the Slicksand. I'm more comfortable following people who've painted these cars before.

A few follow up questions:

When sanding the Primer/Sealer do I go straight to 400 grit, or start with something courser?

Do I use one of those small, square sanding blocks? I spent a lot of time with a 2' adjustable flex sanding board and I've heard of people 'unstraightening' their bodywork doing finish sanding, I want to be sure to avoid that.

Thanks again!

[DARKPT]

The comment to spray primer first comes from steel-body guys, as you use it to seal the metal from rusting before starting your filling. You CAN spray basecoat over the Slicksand, but I doubt I would have gotten a good 400 grit into the Slicksand. The primer also gives you a uniform color base (I had some very slight burn-through on the Slicksand).

You step up to your final grit gradually. From 180, that meant 220, then 320, 400, and 500 for me (400 and 500 were wet-sand). I actually went to 220 on the Slicksand before spraying the Slicksand.

As for sanding blocks, I think I went through all of the different kinds before I was done. I ended up with a set of these for the final prep (mine were about 8" long): Welcome to SOFT-SANDERS

I did use my Durablocks where I could right up to the end, but by the time I got to 400 and 500 I was using the softsanders almost exclusively.

It's a balancing act with the blocks. You want to use the largest one that you can for an area, but not so large or stiff that you're digging into a concave curve. I was a first-timer, and used guide coat for every grit.

If you haven't already done so, review some of the great body-work and paint write-ups on this site. From my bookmark collection, here are a couple:

Started Body Work on #6583

Paint is (almost) done!

Yet another bodywork thread – Scott L sands and sands and sands some more…

[garnet]

Thanks again.

So either a high build 2 part Primer (Urethane), or a 2 part epoxy Sealer (which also seem to be called Primer/Sealer) both work for sealing the paint and as a base for the colour/clear (even though some folks use both)?

I have an extra door, so I'm going to finish it as I have the rest of the car and spray it with the DTM Epoxy Primer/Sealer I have to see how it looks and test my gun on thinner paints.

One of the things for a first timer is not really knowing if you've got the Slicksand perfect or not. I think mine is good, but I've heard numerous times you don't know till you've got the clear on. Hopefully the DTM will help show anything I'm missing.

Thanks for the link to the sanders,

[DARKPT]

There are a few leaps of faith for us first-timers.

Might as well get this one over: You'll have a run or some orange peel, and you'll knock some paint off before you hit 100 miles.

When you get the epoxy primer on and sanded, you'll be able to see if all will be well with the finished paint.

[garnet]

Just to follow up, I tested the leftover Sealer (epoxy) I had on a leftover door and decided to go with Primer/Sealer (2k Urethane) instead. I'm letting it bake in the sun for a day or two and then plan to hit it with 240 grit then 400 grit. Once that's done I'll go to SS or Base/Clear (any opinions on SS vs Base/Clear?).

The Urethane is definitely thicker than the epoxy Sealer and required a larger nozzle, and seems to be easier to sand (from the little I've tested). I'm not sure that the car needed that thickness of paint but wanted to be able to sand and maintain a uniform colour. It's easy to overthink these paints, when I painted a car in high school it was just red oxide primer and topcoat and it turned out well.

Open to comments and suggestions. Thanks for the help so far.