What color primer for going under red?

That would be and I quote : "Custom Products Corporation REP-12A Red Acrylic Enamel. Net Weight 12 Ounces."

I've used it before and it's a perfect match as long as I spray it over bare metal.

If I try to spray it over dried and cured light grey primer, it doesn't match. I ordered it from Snap-on.
This is just a rattle can correct not bulk paint.
 
The chemistry of the etching primer may be incompatible with the top coat. If you etch the steel with acid you will then neutralize the surface by washing it with water and ammonia. I don’t want to give you any incorrect advice.
I'm thinking I may have sanded the bare steel too smooth with 400 grit. People on YouTube say to use 180 on bare steel.
 
Tool box has paint peel on the front panel directly below the bottom drawer. Factory paint is directly over bare steel using no primer. I've been able to match the factory color with factory paint as long as I don't use primer underneath. But now the repaint if flaking off after about 5 years. I'm assuming the repaint is not grabbing a hold of the bare steel as well as I had hoped. The section I'm going to paint is about 3 inches high by 33 inches wide. Also, what grit sand paper for the bare steel before primer? I got plenty of time to think about it since the weather is not quite warm enough anyway. Just throwing this out there.
For reds, yellows, white and some other colors white primer will really make them pop, sometimes too much pop but you can match the red topcoat closely using a tint in the primer. Tinting the white primer before the base coat saves a lot of paint as coverage is much closer to begin with eg black over light grey may take 6-8 coats of base while on black primer only 2-3. These are just examples, any auto body supply store should be able to tint primer for you.

Edit: If you want to cover steel without primer you can use a clear primer for metal.


 
That would be and I quote : "Custom Products Corporation REP-12A Red Acrylic Enamel. Net Weight 12 Ounces."

I've used it before and it's a perfect match as long as I spray it over bare metal.

If I try to spray it over dried and cured light grey primer, it doesn't match. I ordered it from Snap-on.
Do the instructions say to be used over bare steel what do the instructions say.
 
I'm thinking I may have sanded the bare steel too smooth with 400 grit. People on YouTube say to use 180 on bare steel.
You would most likely see a sand scratch down the road without a primer when it shrinks sanding only to a 180 grit.
 
Do the instructions say to be used over bare steel what do the instructions say.
This is how it appears on the can and I quote :

"DIRECTIONS: 1) Surface should be clean, dry, and free of grease, rust, and wax. 2) Mask off or protect areas from overspray if necessary. 3) Allow can to warm to room temperature before use. 4) Shake until mixing ball rattles, then continue to shake for at least two minutes. 5) Move can with dusting strokes letting paint become tacky between coats. 6) Only apply enough paint for coverage; excessive spraying may result in runs. 7) Never spray with the valve partly open; press spray tip all the way down. 8) If spray stops or becomes irregular, rotate spray head from side to side without removing from valve. This will usually clear the spray head. 9) After use, invert can and spray for 2 to 3 seconds to clear valve and spray tip."
 
Scuffing the steel with 80-120 will provide better adhesion but will be highly visable in the finish once it has dried, this is why you use a primer, once dry you can sand it smooth to flatten the surface before applying the cop coat. A mini gun works great for applying primer on small areas like this.
 
The problem with the video is painting 101 you can not check or test color without hide. In video he sprayed one coat we have no idea what hide is it may take 2 ,3 maybe 4 coats to hide.
I'm not saying you might see differences in color but without hide it can look that dramatic.
I'm on vacation I get back in the shop this week I can prove this point.
 
The problem with the video is painting 101 you can not check or test color without hide. In video he sprayed one coat we have no idea what hide is it may take 2 ,3 maybe 4 coats to hide.
I'm not saying you might see differences in color but without hide it can look that dramatic.
I'm on vacation I get back in the shop this week I can prove this point.
OK, forget about the white primer idea.

I went to a body shop supply today. I told them I was concerned about the base coat matching if using a primer first. They handed me a product called "AutoTech Rust Prep." It's a rust inhibitor in a spray bottle, but they told me I can use it as a clear etch primer. They said to spray it on, wait 30 minutes, and then wipe off with a damp cloth moistened with just water. The product will darken the metal, the bottle says.

After that, spray on another product called "Smart SMT3920" adhesion promoter. I told them that product is normally used for plastics. They told me it can be used for steel too. Spray can says to spray it on and wait 30 minutes before applying base coat.

So I guess I will give it a shot. This way I won't have to worry about the primer screwing up the hue.

This bottom 33 inch by 3 1/2 inch strip was painted by me before and the color is an exact match, but as you can see, the factory spray paint is not staying adhered to the bare steel.


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Tool box has paint peel on the front panel directly below the bottom drawer. Factory paint is directly over bare steel using no primer. I've been able to match the factory color with factory paint as long as I don't use primer underneath. But now the repaint if flaking off after about 5 years. I'm assuming the repaint is not grabbing a hold of the bare steel as well as I had hoped. The section I'm going to paint is about 3 inches high by 33 inches wide. Also, what grit sand paper for the bare steel before primer? I got plenty of time to think about it since the weather is not quite warm enough anyway. Just throwing this out there.
The two red color cars that I have owned had a white colored primer underneath the paint...
 
Back in the shop I make bulk paint and paint for aerosol can packaging in house in the tune of millions of cans.
This is a typical silver that will be packaging into aerosol cans sprayed on black and white card to show hide.
It is the only way to show color and read color that it must hide on a black in white card in most cases throwing out exotic candy or pearl colors in that case a step panel would be developed for color.

As you can see the card is sprayed to hide over black and white card it was a single coat. In video above with gentlemen spraying over various color primers we have no idea if his color coat has hide because he omitted this simple test. Color was put on computer showing absolutely no change from white half as STD reading and Black half as TRIAL reading.
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I got the paint stripped off. Wet sanded to 600 grit. The little dimples are the spot welds.

I'm hoping the acid etch will do its job because it's gonna be difficult for the base coat to stick otherwise.

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