Q&A: How do you insure good paint adhesion on aluminum composite material?

By signcraft

Posted on Sunday, August 13th, 2023

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A reader wants to know: “Has anyone found a prep and finishing system that works well on ACM?

“I like the material because it’s light and easy to handle, but I have had problems with paint adhesion on it, especially if it has a glossy finish. If you’re going to finish the whole panel, you could sand it lightly, but if you want to letter right on the prefinished panel, that’s not an option.

“I’ve tried wiping it down with lacquer thinner then hand lettering it, but once it dried you could scrape the lettering enamel off with your fingernail. How do others make sure the paint sticks to it?”

Find answers from readers below and add your own if you can help.


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6 months ago

Here in Oz (Australia) we use 2 products from a company called Flood…ESP (Easy Surface Prep) which you can wipe onto any glossy surface and it does exactly what the label says, ‘Makes Paint Stick’ and/or we add a little Penatrol to the paint we are using and it helps with the paint flow and coverage but again, as the label says, it ‘Makes Paint Stick’. Both are great products. We use them on ACM regularly, acrylic/perspex, even on glass. Give this a try.

Peter Poanessa
Peter Poanessa
6 months ago

We use a lot of acm and have no issue with paint adhesion. We always sand it with 320 sandpaper and then wipe it down with isopropol alcohol. We use both iol based enamel and water based finishes on it.

Juergen Foerster
Juergen Foerster
6 months ago

From your attached photo it looks like you used a semi gloss acrylic paint because that’s exactly what acrylic paint on ACM will do. I’ve never seen One Shot or Ronan do that. If not then try wiping it down with 3M adhesive remover or Rapid Tac cleaner.

6 months ago

I scrub the ACM with steel wool first. Lots of elbow grease! It will give the paint something to grip. I use Oil based One Shot with good success.

Noella Cotnam
Noella Cotnam
6 months ago

I am in Canada, Eastern Ontario to be specific and I also use ACM for many project. I prime my ACM pieces with a light coat of KRYLON flat black spray paint. It doesn’t have to be pretty as it is just a prime coat. Then I can roll any Acrylic latex house paint (Benjamin Moore AURA is my go to) with no adhesion problems at all. I also use this method on expanded PVC sheet (Sintra/Komatex etc.) ; well tested and true.

John Elliott
John Elliott
5 months ago

I realise I’m late to the party on this one, but I have yet to see what I use in the discussion so far.
So, for what it’s worth, I use One Shot’s Hardener 4007 to make lettering enamel stick to ACM.
It works.
Agreed, Penetrol and ESP work as well.
Do NOT use 4007 in acrylic or water based paints.
No need for sanding or steel wool, which, of course, is only suitable if you’re painting the whole sheet or a masked-off panel.
4007 works when you’re writing straight onto vehicle paint as well.
It does speed the paint drying time considerably.
Only use a few drops in your finger pot, and you may have to thin your paint way more often, and / or rinse your brush frequently in turps.

4007 works as a catalyst, and makes the enamel into a virtual two pack paint.
Do NOT pour unused mixed paint back into your paint can ! ! !
Way back, one of my employees poured a couple of ounces of mixed paint out of her finger pot back into the nearly full yellow chrome four litre can when she finished the lettering.
It took that four litres of very expensive paint about a week to go solid.

Only buy the smallest amount you can and keep it in a cool place because it dries out and goes hard if kept too long.

Prickle Patch Signs.

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