Professionals and Amateurs Together

Date Sensitive Finishing Mix

Question

A couple of years ago I made up a batch of polyurethane, turps, and boiled linseed oil, one third each in the mixture. It did an excellent job. Some months later I tried it again, but this time it took forever to dry. Do driers lose their effectiveness over time? Does one need to buy fresh materials regularly to have satisfactory results? — Allan Knight

Answer

Bob Oswald replies: Driers definitely deteriorate with time. The time is probably unpredictable, but in general I recommend not more than a year of storage. Personal experience with linseed oil has confirmed that, although the product was definitely several years old. A new can worked incredibly well. I had a similar experience on a guild project with varnish, again several years old. It never did dry and had to be stripped and re-applied with fresh.

Tags: Finishing