Highland Woodworking Wood News OnlineAsk the Staff, October 2006

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Ask the Staff

Brushing Waterbased Finish

Question: I have a gallon of your Hydrocote Resisthane Plus that I am applying with a 2" Purdy polyester brush (160003) onto unstained bare wood. The initial coat went down very nicely and I had no problems. The product evens out well, spreads well and is satisfactory in every respect except one – bubbles. Regardless of how I apply any subsequent coat, brushing produces an annoying amount of bubbles (literally 100's) which become entrapped in the finish, necessitating the removal of the recently applied coat.

I have tried applying the product like I apply varnish – same result. It seems not to matter if I apply the Hydrocote in a thin coat, heavy coat, quickly, slowly, brushing it on, laying it on, tipping it off or any other technique; the results are the same. I am very unsatisfied with the results. Please suggest what I should do to achieve a better finish with this product.


Answer: Sorry about the trouble you're having with Resisthane. It's really not the best waterbased product for hand application. It has quite a bit of catalyst in it to make it dry very fast and extremely hard. Cabinet shops love it. However, if you don't spray it, the product tends to dry before all the bubbles pop. Generally, as each application of a finish is applied, it tends to dry faster. So the first coat takes the longest, with each following coat drying a bit quicker. If the finish does not have time to flow out level and allow any air bubbles to break before it sets up, they will remain in the dried finish.

The good news is that if you wipe on the Resisthane in thin coats with a rag, it behaves much better. If you want to use it with a brush, try adding Hydrocote's Fish-Eye Stop & Flow Ayd (196097) or, believe it or not, a couple of capfuls of half and half coffee creamer. The fat emulsion in the creamer will effectively slow the drying time, thus allowing the bubbles sufficient time to pop. Just don't add too much. Alternately, you might try a slower drying waterbased finish like our Ceramithane. It is just as tough because it has some polyurethane in it, but doesn't dry as fast, making it more suitable for brushing than Resisthane. Or again, you can try ragging it on. I'm sure you'll get good results.


 
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