Post Primer Cleanup

Last fall I was able clean my parts and get primer on everything. Winter happened so without a heated shop I had to pause. Other projects jumped
ahead this spring. I now have some parts that are dusty and others that are dusty and have spots of WD-40 on them. Do I just use the pressure
washer on the dusty parts? Do I need to use phosphoric acid on the WD-40 parts again or will carb cleaner suffice? Will that hurt the primer? How do
I clean up the WD-40 parts? Some advice would be greatly appreciated!

In your situation I go at it with adequately aggressive washing: hot water pressure washer with a strong detergent. I have alcohol handy to wipe it down immediately after the straight water rinse to remove the water, just in case there are thin spots in the primer.

The dust you really don't need to be concerned with. Once you scuff sand it like you would anyway it will clean off the dust. The WD40 is another issue though. I would wash it with a wax and grease remover frequently changing rags before doing any sanding. Sanding would just spread the oil around. What kind of primer is it? If it is an epoxy primer you will need to put a fresh coat of primer on before proceeding. They usually have a recoat window of about 8 hours and that has certainly passed.

The phosphoric acid is only effective on raw metal.

Im a bit embarrassed to admit that I wasnt planning to sand anything because I wasnt aware I needed to. This is my first painting project so Im still learning. So that may be a secondary question. So first of all, what kind of wax and grease remover do you use or recommend? I used the Van Sickle primer which as I understand is an enamel paint. As such, does that mean I dont need the new coat of primer?

Back to the sanding. Should I be sanding after every coat of paint or just after the primer coats? What do I use to sand? Where can I find it? How do I clean up the parts after the sanding? What will happen if t does not get sanded?

Any in depth response you can provide on either question is greatly appreciated!

(quoted from post at 19:24:28 06/21/21) Im a bit embarrassed to admit that I wasnt planning to sand anything because I wasnt aware I needed to. This is my first painting project so Im still learning. So that may be a secondary question. So first of all, what kind of wax and grease remover do you use or recommend? I used the Van Sickle primer which as I understand is an enamel paint. As such, does that mean I dont need the new coat of primer?

Back to the sanding. Should I be sanding after every coat of paint or just after the primer coats? What do I use to sand? Where can I find it? How do I clean up the parts after the sanding? What will happen if t does not get sanded?

Any in depth response you can provide on either question is greatly appreciated!

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Usually the recommendation is to "scuff" the surface with a purple Scotch Brite pad as opposed to sanding. As Stephen told you the need for roughening the surface is because you are outside the re-coat window. Successive coats of paint bond chemically, but if too much time passes you have to scuff in oder to get a mechanical bond. Good quality paints will have this on the label or you can go to the mfg.'s web site.

Sanding creates a mechanical bond with the coats of paint. The scratches created by the sandpaper will greatly help the adhesion of the paint. Working with enamel 220 grit paper would be good to use. What would be helpful with hand sanding would be a Glit sanding pad, it's a piece of 1/2 foam rubber with sandpaper applied to one side. Also when you sand between coats it tends to sand more off the high places making the finish smoother and more level. What we usually do since we don't have a downdraft spray booth is to paint outdoors or in a dusty building and some of that dust gets into the paint. Sanding also removes that dust so when you are done the dust nibs in the finished paint is a minimum. After sanding I normally use a soft bench brush and compressed air to clean the parts to spray.


Any auto supply store that sells paint should carry a wax and grease remover. Any of them should be alright. Myself, I started using Dupont Prepsol Solvent and that is all I've ever used. I get it at a local store that sells automotive paint. It's mostly naphtha and what it does is liquefy any oil or wax on the paint which allows you to carry it off with a clean cloth. Since the rag picks up the contaminate it's good to frequently change rags.

As far as a new coat of primer, using an oil based primer that is unnecessary. You only need primer on raw metal. If you were using an automotive epoxy primer then another coat would be warranted. That would be necessary even if you applied the primer the day before. With epoxy you have like eight hours to topcoat it with something or prime it again.