Poly Wipe Marks on Desktop

[Dave Jurek]

Hi. I've built a desk for one of daughters. For the desktop itself, I've sprayed on a colored SW acrylic latex paint. My intention was to apply a polyurethane over it to give the desktop a hardened surface.

I bought some polyurethane, diluted with mineral spirits 50/50 (to make a wipe-on) and started applying with a rag. Except now I can see the swirl marks in the paint after applying the poly. I guess the mineral spirits/thinner is messing with the paint? How do I apply poly without creating poly application streaks in it?

I've sanded off the polyurethane. I'll need to re-apply the latex paint before trying again.

Thoughts?

[John TenEyck]

If you used a good acrylic paint you don't necessarily have to put anything over it. It should be hard by itself. If it's not hard then you have a potential problem as putting a harder finish over a softer one usually leads to problems. When something gets pressed against the harder topcoat it's likely to crack because the stuff under it is soft and flexes. And are you sure the swirl marks you saw were from the poly and not in the underlying paint? DAMHIK.

For a streak free finish - spray.

John

[Dave Jurek]

The paint is not soft. But I may not have sprayed it properly?

A desktop needs to resist pencil writing on paper, water glasses left on it, eating food, etc. A 11 year old will be using it. I'm not sure acrylic by itself is resilient enough. Would you do acrylic only for a table top?

The streaks showed up after the application of a paint thinner/mineral spirits diluted poly urethane applied with a rag. Yes I'm sure that put the streaks in the desktop. Perhaps a diluted poly applied on a water based paint with a rag just doesn't work? Or perhaps when I sprayed the paint on, I didn't get a heavy enough coating? The paint was essentially dried instantly as it came out of the gun onto the piece.

[Steve Schoene]

It's a tough finishing task. I think about a sheet of polycarbonate or other plastic on the top. Just be sure the paint won't "block" to the plastic so you can change it if you want.

[Dave Jurek]

Well....after a bit of research, I think I've used the wrong product for hardness and durability. Going strip back down and use a oil based enamel. Plus SW told me their latex and polyurethane are not compatible. Live and learn I guess.