Paint Dilemma - grey or black primer and a guide coat?

The dilemma...

I'm using a Washington Blue single stage acrylic urethane. I was thinking a black primer base might be better than light or medium grey for the sake of keeping the blue as dark as possible. But then I started thinking maybe I'll have trouble with guide coats if I go with black. Never used black primer none the less blocked it.

The questions:

Will a lighter "guide coat" be effective over the black, like light grey or a color of some kind?

Will the black primer really make a difference in the overall outcome of the color with 3-coats (or so) of color?

Ordering paint today, so some professional feedback would be appreciated!

Thanks guys!!

 

I would think it would be easier to see dark material in the small pits of the primer rather than light material in a black primer while working with it. My vot would be for a grey primer and a black guide. I've never blocked black primer though.

 

If you are going to drive it in primer for awhile, I wouldn't even use the guide coat. The guide coat is to be put on right before you get ready to paint it for the last time.

 

Light grey primer as a guidecoat over black works very well.

 

you can use any color primer you want, just use black sealer before paint.

 

Not going to drive it in primer. Color will immediately follow, or at least within a few days. If I re***emble the car just in primer I will never go back and shoot color. I know myself. HAHA!

Yeah, the dark guide coat always works well over a light grey primer. Never tried the reverse... light guide coat over a dark primer.

Anyone shoot black primer (DTM epoxy, etc.) and use a guide coat for sanding?

 

I thought about THIS as well! Going with a grey primer and then sealing it with black. That is a VERY good idea, actually.

 

Go with a lighter or neutral primer and a dark guide. Then a dark sealer before paint. The sealer will give a good uniform color and keep your top coat from "ringing" around any breakthroughs in the primer. The dark sealer will also make the color cover much better since blues have a tendency to be transparent.

 

Thanks!!! I think I'm going to go this direction. I like this theory.

Thanks for the input everyone! It's much appreciated!

Now if I can just get my metal work done...

 

Primer color and guide coat color are for the most part an individual preference. Just make sure they have a good contrast so its easier to see the imperfections and scratches. The sealer color that you use is more important than the primer color due to the transparency of some top coat colors. Most color formulas have a recommended sealer color provided by the manufacturer.

 

Dark primer works well without a guide coat. It will lighten where you sand. If you are wet sanding you may have to let dry a bit.

 

Okay, so ended up getting a grey high-build primer and a black DTM Epoxy primer/sealer to top it with. Then my color...

Thanks guys! I appreciate the advice!

As for the color itself, they only recommend a type and conditions, but don't say anything about the recommended shade or color. Just going to ***ume some transparency (rather there is or isn't) and go with the dark.

Man... I'm super excited now!!!

 

I see you already bought your paint, no one mentioned getting your sealer tinted blue.

 

I'm not sold on the sealer deal. You block everything and it looks perfect, then you put sealer on and you're stuck with surface you get. You can't block sealer can you?

 

I didn't want blue. Plus the stuff I wanted to use didn't come in blue.

Bob has a good point and an even better question... Can it be sanded without losing the benefits of a sealer?? Thoughts??

I did indeed buy 2K high-build in grey, and a black epoxy primer/sealer to use as a sealer.

 

Now you sound like me. If it runs it will never get blown apart.

I used to do most of the grunt work when Lynn and I owned the shop. He was the paint and body guy I was the welder and mechanic guy. He never put light primer under a dark color. We always just used a contrating color for a guide coat so if it had dark primer he just used light primer for a guide coat it worked fine. I have blocked a ton of 'em.

 

I use epoxy primer as a sealer....thinned slightly so it lays down nice. It can be blocked out, but you have to put on extra coats. Works well both ways.....

 

So the parts are sealed with the black epoxy primer/sealer. I unfortunately got a couple runs that will have to be blocked out and re-sealed.

The finish turned out pretty smooth to the touch. I'm still struggling with the idea that I shouldn't cut with 400 before paint to make sure my top coat goes on like gl***. Never sealed parts like this before. I hope I'm not making a mistake not just cutting it. Seems like some kind of mechanical bond would be helpful to the top coat.

 

If you are going to drive the car you have to think about chips. with a light primer under a dark color it will show up . also the sealer can be a little rough but a little color sanding will take care of this after the final coat of clear or if no clear used color sand the final coat of color.

 

This is part of the reason I'm doing the black sealer over the lighter primer, for a little added protection from chips, and what not; but also to prevent any transparency problems with the paint (if any).

My real concern at this point is the sealer not being what I would consider an ideal finish to go under my color/top coat. Seems like it should be smoother. Especially since the paint will be dark and will show EVERYTHING. (NOTE: Single stage. Not base-clear two-stage) I spent hours getting the high-build perfect, only to shoot it with a sealer that is going to have a less than perfect finish before topping it with beautiful paint.

Advice? Should I should say to hell with using the black epoxy as a seal coat and treat it like any other primer and hit it with 320 or 440 and just apply my top coat? I've spent hours getting the finish really nice so my final color coat is nice and straight. I'm going to be really upset if any imperfections from the sealer carry through, and it seems it should with the finish it has now.

 

Wow, not sure where to start on this thread. Lets start with the original questions.

1. Yes a light grey primer will work as a guide coat over black primer. I've usually gone the other way, spraying grey primer and mixing in a bit of black toner on the last coat for a guide coat. or just go the rattle can guide coat way.

2. No. Covered is covered. If your not spraying enough base to cover the primer you will have problems with color hold out. This is why they make black and white checkered coverage stickers, and paint spray out cards have something similar on one or two edges. The color of primer is generally irrelevant, unless you intend on spraying yellow. They took all of the good stuff (lead, and chrome) out of the yellow and it takes about 11 coats to get it to truly cover.

3. Sealer can be used for several different purposes. Mostly used to ... get this.... seal off an old paint job, to prevent old paint from lifting or to give better adhesion to certain substrates like e-coat. If some thing is primed and blocked, and sanded to 400 or so, there is no reason to seal. Some high end usage of sealers would be on Jaguars or other high end nonsense where the under hood color is a colored primer from the factory. In order to get an exact factory appearing finish a suitable sealer must be used on areas that are not "painted".

 

Thanks for the response Kris!

I have always read that it is a good idea to seal when filler is used, just to help reduce the possibility of bleed-through from the plastic filler catalyst. Now, I didn't use a whole heck of a lot of filler at all and what I did use I feel was mixed plenty well, but thought the added protection would be nice in case I missed something.

So you're pretty much saying "screw it! Just block it and paint!" I gather.

Man... Mad respect to all you guys who do this for a living. It has been one hell of a learning process, and the amount of work getting things straight and flat is daunting!! Or should I say... HAUNTING?

 

If you use filler it needs to be primed over. Preferably with a high build primer. And block sand that, wet, from 220-320-400 you could skip the 320, but be sure you guide coat and sand all 220 scratches out.

If you're saying that you've heard that it was a good idea to use a sealer over filler before priming, that makes no sense to me. Fill prime, (or high build what ever you wanna call it) typically won't lift filler even if the edges aren't properly feather edged.

One tip: Dig through a pile of paint sticks at the store and find the straightest paint stick you can find. Use that for wet sanding. Soak your paper wrap it around, its the best wet sanding block ever. No need for a sanding block "kit".

 

Great tip on the sanding block! Very cool!

I indeed used 2K high-build primer after filler work, and I used the black epoxy primer/sealer over THAT. Prepped primer with 180, 220, 320, then prime. Then prepped for the sealer with 320 and 400 (probably overkill). Then shot the sealer. Not a scratch to be seen anywhere, that's for sure. HAHA! But it seems it should be knocked down. I guess I'll find out as soon as I cut down and block some of these runs.

 

Actually. sealer IS a good thing to use if your car has a lot of filler/glaze on it.
Not only does it help to prevent bleed through, mostly on light colors, pearls are especially prone to it, but it also helps prevent solvent from penetrating the primer coat, into the filler materials. This can later cause solvent pop, as the solvents can migrate and get together to form a solvent "bubble" and later lift paint.
Bleed through was thought to be a byproduct of the dye used to color the hardener in body fillers. This DOES case problems with very light colors in some cases, but the peroxide in the hardeners can cause bleaching as well...even when some filler manufacturers went to a white hardener ( which people hated because you can't see the amount of hardener used, and when it's fully mixed it) the problems persisted.
The blocking of solvents from going too deep, or getting absorbed into the fillers (body fillers, even catalyzed glaze ARE absorbent!) is that the solvent swells the filler to a degree, and later, when it outg***es, the filler returns, or shrinks, back to it's original size. If you've done your sanding while the filler is expanded, when it shrinks, you will see sand scratches, at the least, and wavyness at the worse.
So sealers area good idea for bare metal builds, too. Unless the metal is perfectly straight!

 

Should also note, with epoxy primer used as sealer.....you have a 24 hr window to recoat without sanding. After that, it gets too hard and you need a mechanical bond.

 

That is all the same stuff I had been reading as well. Thank you for re-iterating it!

Maybe the better thing would have been to shoot the sealer over the filler instead of over my high-build. Too late now, I guess. Well, these parts are easy enough to redo if I have issues. The BODY is another story. This is why I want the strategy worked out now so when I finally get to the body I can get it RIGHT.

So, the still unanswered question is, should I just block out the sealer I've laid down so it looks stellar for color and say goodbye to the sealing properties?

 

I didn't see anything about this on the tech sheets. This is good info! So does this imply that top/color coat should be applied within 24 hours as well? Would this also imply that AFTER 24 hrs the sealing properties will remain even if blocked? (guessing not, on the later)

 

I shoot epox right before I paint top color.If you donot sand the epox the paint will lift.I just finished a fal****,bodyman painted epox took off a month come back finished body work the paint did not stick 2 years later took a putty knife lifed paint right off.had to repaint whole car cusmer was very upset with other painter.

 

Scott if you are still using the Quantum the epoxy in it gives it much better solvent resistence compared to regualr fillers so you shouldn't have a problem with that.