I learned something new today that and I thought it was worth sharing. Because of today’s strict new VOC (Volatile Organic Compounds) laws most Urethanes are now water based. Most wood fillers however are still an oil based product. So you ask what’s the big deal?
If you apply a water based urethane over an oil based wood filler it will most likely turn yellow or at least not match the color that you started with. I’ve actually learned this the hard way a few times but I had no idea what actually caused it. So, a painter suggested that next time I apply the urethane prior to filling any holes. Get all your coats of urethane applied, all the sanding and preparation done. Then go back at the end and apply the oil based wood filler. You know what…..it works fantastic! Next time you’re working with urethane give this a try, I think you’ll be very impressed.