Hello,

We are a custom cabinet shop that relatively recently switched to Acromapro Matador paint. We have now had 2 instances where the paint can be scratched off edges with a fingernail without a lot of force.
We have ran many tests to try to fix and forcefully make the issue happen.
We have tried oversanding (polishing), not sanding primer at all, easing the edges just a touch more, less catalyst, more catalyst... Everything we can think of, including 2 back to back top coats as well as scuff sand between topcoats. Doesn't seem to matter what we do, the edges seem to be failing. Everyone I talk to leans towards sanding but we sand face and edges of 2 coats of primer with 320grit. We use their unisurfacer primer as well.

Anybody have any thoughts? The company has not come forward with any solutions except sand edges, more paint and paint within 8 hrs of sanding..
We apply 2 coats primer and a single topcoat typically. 5-6 wet mil on each application.

Thank you!

Are you edged breaking your sharp edges?

What material are you painting?
What grit are you sanding to on your wood?
Have you tested adhesion after just primer? After your second coat of primer? I’m assuming you are scratching back to wood and not to primer.

Almost everytime I have ever tried 2 primer or sealer coats for a finish schedule it bites me in the butt sooner or later. Doesn’t matter if it’s solvent or waterbased. There is a reason topcoats cost more.

Are the colors mixed in a clear or white base? We have been spraying Matador for 20 years. The darker colors mixed in the clear base tend to be softer than ones mixed in the white base. The clear base is also catalyzed at a different rate. 12% for white, ( we do 4oz per quart) and 16% for the clear base.

Break the edges and don't over-sand them. We use 280g, and try not to polish.

We do one box coat of primer (unisurfacer) and one finish coat.

After reading your post more closely, I would would agree with FM above on only doing one primer coat. That is likely the problem.

Yes we break are "sharp" edges, we sand with 320 on our final primer sand. If we go any rougher we see it in the dark colours. This paint is in a clear base and we catalyze 16%. Material is either HDF or maple. We aren't scratching through to raw wood we are just scratching the topcoat off the primer. We have done a test sanded with 320 and top coated right away with the same result. Even after 3 weeks we can still dent the topcoat with a forceful fingernail.
FM #3, what goes wrong when you do 2 primer coats?

Okay, if it’s back to primer that is a completely different issue. My best guess is you
1) aren’t sanding between the topcoats on your edges
2) need to use a lower grit on just your edges
3) are missing your recoat windows and it’s showing up in this area where your finishes are going on lighter than the horizontal of the front and back and the finish it hot enough to give you some adhesion on front and back but not edges as it’s drying so fast.

Primer and two coats or sealer and two coats I have seen so many issues over 25 years of business that it’s almost a book. But generally poor adhesion, poor hardness, and wrinkling. Keep the primers and sealers to one coat is my advice.

I have found the darker colors in the clear base, particularly blues and greens, are softer than the colors mixed in the white base. On the dark colors sometimes we will do two coats of the matador followed by a coat of innovat. This is a very nice finish and is harder than the matador clear base top coat. They also make a clear primer that can be tinted called transurf primer that you can lay down a couple coats of this primer then top coat with innovat clear. Don't use clear surfacer. It doesn't sand nearly as well as the transurf primer.

Thanks everyone for their input. How long would you say until the dark colour in clear base is hard enough you cant dent an edge with fingernail anymore?
I understand they say about 21 days to full cure in air dry.
We scuff sanded after 2 coats of dark green and added a coat of innovat clear thinking this would give us a hard layer but we can still dent and scratch the edge 5 days later air dry in about 25degC.

Your denting and scratching are two different issues. Dark colors in clear bases for us take weeks to truly harden up. Doesn’t matter the manufacturer or the type of finish. They are good enough to ship and install in a week. I would just tell everyone to keep their fingernails away from them for another couple of weeks. You just have to live with this and work around it.

The scratching back to primer is a failure and has to be resolved ASAP.