Painting Slates that have been previously used on a roof.

I am having trouble with my acrylic paint peeling off of slates that I have painted.
When kept indoors, there is no problem.

But these slates have been painted with the intent that they could be placed in an outside garden. I do top coat the side of the slate that has been painted with two coats of polyurethane that is specially made to withstand the outdoors.
Min-Wax Helmsman. W/Spf protection.

Unfortunately, I am finding that the painting isn't holding up.

Do you have any suggestions? This particular surface is not listed on your website.

Comments for Painting Slates that have been previously used on a roof.

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Nov 10, 2019

Slates
by: Cheryl

The Minwax Helmsman Spar Urethane contains "special oils' and therefore will inhibit proper adhesion when you paint with acrylics on top. You will need to paint with either oils or change your sealer to a water-based product.

If you choose to paint with oils you won't need to finish the painting with a protective coat.

If you go with the water-based sealer and acrylics, then you'll need an exterior water-based varnish with UV protection. Be prepared to apply a new coat of varnish every year, depending on how much exposure to the elements the slates are enduring.

I do hope this helps! Cheryl

Apr 01, 2024

Advice
by: Denise

I would love to know what type of varnish did you use to seal your slate, was it exterior varnish and water based?
Thanks

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