Brushable Waterborne Poly for Woodwork

Advice on choosing and applying a brushable waterborne polyurethane for interior architectural trim. July 23, 2014

Iím not a water-base guy but I have to do some interior windows and trim in a house. I don't have time to order and my choices are Miniwax polycrylics, Ben Moore stays clear and Varethane water poly. Does anyone have any feedback?

Forum Responses
(Finishing Forum)
From Contributor G:
I've used the Minwax, but I sprayed it. It came out nice and dried pretty quick. I'd recommend a Target product, although you said you have no time to order.

From contributor R:
Once in a while on an odd project for one reason or another we use the Minwax poly and it's always worked well and held up well for us.

From Contributor B:
I use Cabot's Waterbased Polyurethane exclusively for all kinds of restoration work and refinishing work when WB is the best option. I am a pro of 41 years and started working with this medium about ten years ago out of self-defense! When the manufacturers use this coating, and you have to fix freight or moving damage to this coating, compliance becomes essential. So I added the use of this material to my arsenal.

The reason I prefer Cabot's over the others I have tried is simple - the others are milky when applied, and Cabotís is an amber clear (caveat: too many coats of semi-gloss or satin will get a bit cloudy, just like any coating with a flattening agent). It is every bit as hard as any other WB Poly, sands to a powder like a dream, and is compatible with damn near everything. As long as the substrate is completely dry and the Cabotís is fully cured anything is possible in repair work.

Some tips, from experience:

1. Use only the very softest and flexible synthetic brushes. Always wash out a new brush before use, immediately after use, and again before re-use so it is dampened. Always use soapy water, then rinse clean. A dry brush produces bubbles by the bushel. So does aggressive de-wetting against the inside of the container. Be thorough.

2. It runs quickly on vertical surfaces, so too much poly on the brush is a problem.

3. Tip off to remove bubbles. It flows together well, but learn when to stop brushing. Above all, keep the brush tip wet with poly

4. Follow the recommended drying schedule until you know how much to crowd it - a too-soon re-coat will cause the first coat to foam slightly. It may dissipate, or it may not. Then you're screwed.

5. If you shake it you have to postpone the work till the bubbles dissipate - several hours, or a day.

6. Sand between coats, but use 320, 400, or 500, depending on how many carbuncles you have to sand out. Scotch-Brite works great, but it won't remove dust bumps or bubbles in the cured surface.

7. Stearated paper is not a problem with careful pre-cleaning - see #8.

8. Always thoroughly wipe off sanding dust or any surface before coating/recoating. Use a lint free cloth evenly dampened with a 50/50 mixture of water and denatured alcohol. Let it dry/wipe it dry and then check for missed dust - sanding dust will not dissolve into the new coat.

These are the basics, and they are important. I buy mine online for the best prices. Have fun - it's good to learn new things!

From Contributor B:
The Minwax polycrylic sprays well, (available in aerosol, but runs too easy) but doesn't brush as well as the WB Polyurethanes in my opinion. Of those three I like the Varathane water-based poly.