A furniture refinisher in Klamath Falls recently reported a problem with a certain brand of wood filler he was using with juniper. The filler caused minor "bleaching" of the reddish heartwood around the filled hole. "Bleaching" was particularly noticeable after application of lacquer.
Mark Hanson, a wood products designer in Portland with extensive experience with western juniper, was asked about this problem. Mark said he uses Famowood® water-based filler and has not experienced any problems(1). He also said that Famowood's® cherry-mahogany tint works particularly well with juniper.
Randy Lewis, Laurence-David, Inc., was also contacted. Randy tested several fillers his company produces and reported no difficulties. According to Randy, Laurence-David's® D-70-CS (Red Oak) filler matched juniper's heartwood quite well and caused no discoloration.
The filler that resulted in the "bleaching" had a strong ammonia smell. Based on this observation, Dr. Joe Karchesy, Wood Chemist at Oregon State University, hypothesized that discoloration could be caused by filler pH. Dr. Karchesy suggested testing solutions of varying pH (from acidic to basic) on a sample of juniper to confirm whether or not pH is a factor. No plans have been made at this point to conduct these tests because there appear to be acceptable commercial alternatives available.
It goes without saying: Test fillers and finishes on a sample of juniper if you are unfamiliar with the products or never used them before with juniper.
For More Information: Scott Leavengood, OSU Extension Service (541-883-7131)
1. Use of trade or company names anywhere in this publication is for reader information only, and does not imply endorsement of any product or service by organizations or individuals which contribute to this newsletter.