Self etching primer coming off like dust (1 Viewer)

[drowzyGX]

Got a new pair of sliders, bare steel, and wanted to paint them prior to install. Went through the process below to prep and prime them. Waited 24 hours to let it cure before painting. Took a dry paint brush to them today prior to painting, and primer just brushed off like dust.

it didn’t go to bare metal, and most of the sliders are still covered, but it just turned powdery in a lot of spots.
Products Used
Scotch pads
Wire brush
Shop towels
Acetone
Microfiber towels
Rust oleum self-etching primer
Paint Area
Covered carport. No sides. Was about 95-98 F with high humidity (east of Atlanta). Not sure if this messed up the primer?

Prep Steps

1. scuff entire slider surface with scotch pad
2. Use wire brush on any spots with light surface rust
3. Another round of scotch pad
4. Wipe down everything with dry paint brush
5. Wipe down with acetone and shops towels
6. Wipe down with dry microfiber

Primer Steps

1. Shake can
2. Spray somewhat heavy coat. First coat was opaque, worried this may have been my screw up
3. Let it dry for ~15 minutes. Was dry to touch.
4. Repeat another somewhat heavy coat
5. Let it dry for ~15 minutes. Was dry to touch.
6. Repeat process. Went through 2 cans of self etching primer.

Came out today and the spots on the surface looked rough - almost sandy if that makes any sense. Brushed the surface off lightly to remove any dust or debris prior to painting, and that’s when primer just started coming off like dust. A light once over with green scotch pad took off even more primer.

Feel like an idiot because this seems like a really easy and straightforward project. Not like I’m trying to paint the truck or anything.

Thoughts on what I did wrong?

do I need to sand this entire thing down to bare metal and start over? Can I get away with a some heavy passes with 80 grit sand paper

are the temp and humidity problems? no big deal if so…I’ll just have to have a shop powder coat them

thank you for any advice!

 

[Camotubebender]

Acid etch primer is for adhesion and is usualy sprayed on in a light coat and then epoxy primer or sealer is sprayed over that for coverage. It sounds like your trying to get coverage with the acid etch so your putting it on too thick.
I would skip the acid etch- have them sand blasted and get epoxy primer on them as soon as possible after that dries your ready for paint. Or you could sand them down really good and get epoxy primer on them but blasting would be best.
If your doing it with spray cans you will want to make sure you get a 2K epoxy primer in a spray can.

 

[Camotubebender]

Also use 2K for the black or whatever color your painting if possible-you'll be glad you did.
Spraymax is a really good choice that a lot of bodyshop supply stores carry or you can get it on amazon.

 

[drowzyGX]

Thank you for the details and advice. Didn’t realize that about the primer. if I sand real good by hand instead of getting them sandblasted is that going to lead to potential problems down the road as far as longevity?

If sandblasting is the better option for fixing this, I may just let one of the local shops powder coat them, too. Place near me charges $90 / hour for sandblasting and then $200 to powder coat a pair of sliders. Call it $300 for the whole deal.

if I sand everything down that’s probably an hour minimum of sanding across the 2, probably 39 minutes to clean both thoroughly after sanding, then the 3-4 cans of the primer you recommended and 3-4 cans of paint, and new filter cartridges for my respirator.

may just let’s the pros do it at this point.

I should have done more research ahead of time. The guide I found just used the acid etch primer, and had the sliders thoroughly coated prior to painting.

 

[cruiserpilot]

The etch primer is perfect for initial prime. It will powder off, that’s not bad. Use med grit to smooth
it off. Then a high fill primer on top of that. I prefer to wet sand with about 400 grit to remove sanding
swirls and marks. You can paint over that or ad another primer layer if you’ve sanded down to metal.
If you have good primer laid down, it would be easy for the powder coaters at this point to
give you a good finish.

 

[drowzyGX]

Hey y’all - really appreciate all the advice. I think it may be the paint and not the primer. The below picture is after taking a green scotch pad and going over the primed, painted, and dried slider.

the black paint came off like it was dust or dirt, but the primer is on there and only seems to come off with sand paper (like I’d expect).

is the best path forward doing a light sanding of the primer (400 grit or so), a wipe down, and then some of that 2k epoxy primer, then paint? Or would I be good to paint right over the primer layer since it looks like it’s adhering to the metal?

 

[SHIfTHEAD]

Wipe it down real good to make sure there is no dust left. You want it smooth to the touch. Rattle can primer is always dusty, and I rarely ever use it. The key to rattle can adhesion is how it's applied. And how long you allow it to cure. Here are my steps regardless of what color or what I'm painting.
-Prep it thoroughly. Sand, wipe, and repeat until it's the subsurface you want. Whatever you can feel you will see when painted.
-Degrease thoroughly. Since I don't use primer anymore this stage is done with brake clean. Wash it off, both sides and let it dry thoroughly! If you have to handle it put on fresh nitrile gloves. Those gloves will only last a few mins. So handle minimally. For primer you could use mineral spirits or denatured alcohol I think. But test to ensure it won't dissolve the primer.
-Once degreased and dry you are ready to paint. The first coats are very important to get it to adhere. Go in knowing you are probably going to spray it 4 to 5 times. The first coat is literally a dusting. You should barely see a color change. Wait 5-10 minutes and repeat, another wait and another light coat. By now (3 dustings) you are seeing some ok coverage and at this stage are ready to put on a wet coat.
-The wet coats are just barely wet. Spray it until you see the surface shine and move on. Don't overdo it. You don't want runs. Wat 5-10 again and another wet coat. You should have solid coverage now. Keep spraying until you have the coverage you want. Don't wait for more than about 20 mins between coats.
-Now the big one, once you stop you are done painting on it for a week. Unlike 2K paints, rattle can is an emulsion paint. It will flash and feel dry but there is still a lot of solvents in the paint. If you spray it again before they have cured you will end up with the original coats wrinkling up as the new paints solvents start to loosen the original coats.

This is the method I use when painting anything I want to look good. I've painted lots of stuff with rattle can and the finish is good and has decent chemical resistance. Once cured it's very durable. But any strong solvent could damage the finish. I have several sets of wheels I sprayed with silver aluminum color and they still look great years later. Engine bays with satin black, valve covers, motorcycle frames, etc.

Remember, the base coats are what allow the paint to adhere. Less is more.

 

[drowzyGX]

Damn, thank you! Bookmarked this post. Really appreciate your detailed instructions and insights. I seriously underestimated my prep and apparently rushed a lot of the painting process. The knowledge on this site never ceases to impress.

appreciate you taking the time to write all this up. Looks like I’ve got my work cut out for me to get these painted right.

 

[drowzyGX]

Quick update: I think this round of paint went much better.

I didn’t go out and buy new paint or primer, but I re-did my approach.

the primer appeared to adhere just fine. So it looks like my problem was an awful paint job. Took about 45 minutes this morning and scuffed the one slider with a scotch pad. Brushed it with a dry paint brush. Then vacuumed it. Finally, wiped it down with a microfiber. Ran my hand over with a nitrile glove, and nothing came up.

followed at @SHIfTHEAD advice. Applied 5 light, dusting type coats. Waited 5 minutes between each coat. Temp and humidity seemed better today, too. After the light coats, I gradually laid wetter coats with 15 minutes between.

slider looks so much better between coats - no splotches or streaks - like last time when I was just laying heavy coats and waiting 5 minutes. Gonna do one last wet coat then let it dry overnight. Will update tomorrow with the results.

thanks a ton for everyone’s advice!