Wipe-on-Poly streaks

[Roger Marty]

Based on my advice, my brother finished a table with wipe-on-poly and sanded with 400 grit between coats.


After 5 coats, it looks great except when viewed and an angle where it is all streaky. I'm thinking that must be the 400 grit sandpaper caused scratches?

What did he/we do wrong??


372158

[Larry Frank]

My experience is that it is not the sanding. It is not easy to cover a long surface with wipe on poly. You need to be careful to get even coverage on the whole thing.

[Lee Schierer]

It could be any one of several things. If he was using a sanding block the surface being sanded may not have been perfectly flat or some of the strips changed due to ambient moisture changes. He may not have applied the finish evenly. The finish may have soaked in in some areas more than others. The finish may not have been completely hardened.

[Jamie Buxton]

If you're down near the end of a can of wipe-on, it may well streak. I believe what's happening is that the thinner has been evaporating from the can when you've been putting the earlier coats on. Wipe-on avoids streaks by having so much thinner in it that the finish has the time to flow out on the workpiece, and fill in any coverage streaks left when you apply the stuff. One fix is to add some more thinner when you get down near the end of the can. Another fix is to open a new can when you're doing your last couple of coats.

[Bennett Ostroff]

Hard to say if that's sanding scratches or some kind of streaking in the poly. You could try sanding more lightly with 600 - after several coats 600 should be sufficient. And I wait as long as possible (at least a week) before doing any sanding on the final coat to avoid scratches.

You could also try brushing on the wipe-on poly with a foam brush. This works great for me. Plenty of time for the finish to flow out and helps avoid streaking you sometimes get from wiping around a very thin finish.

[Dave Zellers]

You could also try brushing on the wipe-on poly with a foam brush. This works great for me. Plenty of time for the finish to flow out and helps avoid streaking you sometimes get from wiping around a very thin finish.

This is what I think is going on. For something that size, wiping is tricky. I would make a large applicator, maybe 6", get the finish on quickly and avoid over wiping. Control the amount of finish that soaks into the pad by dipping it in a tray with just a thin even puddle of finish. Total application time maybe a minute at most. If he were to apply 3 more coats, by the final coat he would have the process down. Wet the top and sides, a quick final wipe on the top, once around the sides and step away.

[John TenEyck]

The only way I could get a streak free finish on a large slab was to add about 25% mineral spirits to it and apply it with a foam brush. However, I think the pad idea would be even better.

John

[Bennett Ostroff]

The only way I could get a streak free finish on a large slab was to add about 25% mineral spirits to it and apply it with a foam brush. However, I think the pad idea would be even better.

John

Do you mean adding 25% mineral spirits to the wipe-on poly or to full strength poly?

[John TenEyck]

Do you mean adding 25% mineral spirits to the wipe-on poly or to full strength poly?

To the Arm-R-Seal wipe on poly I used. If you are thinking that would make the solids content really low, you would be mistaken at least as far as ARS is concerned. It has a solids content of about 35% which is the same as Waterlox and most other varnishes. ARS is thin by formulation, not because the solids content is low.

John