I'm brushing a custom cherry addition to a kitchen with Varathane water base poly to match the existing finish in the kitchen. I am also going to sand and add a fresh coat of poly to the existing kitchen after my install. I have never used water base before, though I have had great results with Miller oil base polyurethane, applied with Sherwin Williams ProVal brushes. I don't like how much thinner the water base is, and I'm noticing as I apply the water base (this time using Purdy Syntox, synthetic varnish brushes) that I am developing buildup on the underside of drawer fronts and vertical surfaces. I never had this problem applying oil base, because it always seemed to hold its form, even against gravity. I have the following questions:
1) Are there different application techniques for water base that get the same finish as oil base?
2) What do you think the best brushes for water base poly are?
3) When you do develop a large dried drip hanging off the bottom of an edge (in this case the backside of a drawer front) is it necessary to resurface the whole piece and restart?
From contributor A:
I have used Flecto Varathane many times. I do however use spray application mostly, but have brushed on occasion. There is one thing I do differently when brushing a finish than I do when spraying a finish. I finish the front of doors and drawer-head first and work on the back surfaces second. Let me explain:
1. Lay door face up on your work surface. Apply poly to the face and all four edges.
2. Pick door up, holding in the center of the back, use a clean damp rag and clean around the back edge of the door to remove any drips or errant brush marks.
3. Allow to dry.
4. Place door face down on work surface and finish just the back of the door, the edges were finished with the front.
This process will eliminate the drips and runs you are experiencing. One more suggestion - if you do get drips and runs, remove them with a single edge razor using it like a mini cabinet scraper to remove most of the drip and then sand level with the surrounding surface.