Finish Troubles on Cedar
Cabinet doors were built with poplar lumber frames with inset panels made of 1/4 inch maple faced MDF. The poplar lumber was blanked out in advance and air dry acclimated for a couple of weeks before we built the doors. After the doors were fitted, we put benite sealer on everything. The face frames were wiped lightly with a rag and the doors were coated a little heavier with a brush. So far so good. I think we followed solid wood-ology precepts.
And then the bad stuff happened. The painter stopped by with some doors today that were perfectly dry on the front face but completely gummy (like scotch tape in the sun) on the back sides. These cabinets have been installed in the house for about 5 weeks.
During roughly the same time period, we built a project with similar specifications that has not manifested this gumminess. The difference between the jobs is that one had aromatic cedar and one had pre-finished maple plywood boxes. On both jobs, we let the benite dry to the touch, then stored the doors hanging on the cabinet. On both jobs, there were doors that probably did not see much daylight before the benite completely dried.
When I learned of this today I checked with the painters on the second (non-aromatic) job and there were no extraordinary issues. The movie in my head recalls an article once about how you should not mix construction adhesive with cedar in saunas because of a chain reaction off-gassing with this combo. Could the aromatic cedar be off-gassing in a way that causes this gumminess? Any ideas?
I had a similar problem on some cedar lined chests I built once. The pieces were finished with precat lacquer. Everything was fine with the top open a day or two, but as soon as I shut the lid for a day, the finish around the lining got a little soft and sticky. There is something outgassed from aromatic cedar that will mess with some finishes. Don't have a recommendation for you.
You just solved a 17 year old mystery for me. I made a cherry, cedar-lined chest in high school woodshop and the same thing happened to me. To this day, when I open the lid, I have to give a little extra tug to pop the lid loose because it gummed up on the top edge under the lid.
The first idea that pops in my head is provide some ventilation in those cabinets somehow. My father made a cedar closet 20 years ago with the same cedar planks I used. He also lacquered the door to that closet. But, there was a 1" gap on the bottom and about 1/2" on the top. There was no gumming problem. I don't know if that will solve your problem, just giving my experiences.
You might want to check out the MSDS for Juniperus Virginiana, Eastern red cedar. For the life of me, I can't remember the name of the active toxic ingredient in ERC, but when the oils oxidize, they will react with a number of finishes, as mentioned.
First suggestion: disguise a vent system for the cedar, and don't finish it at all. Once the oils oxidize, the cell membranes harden off and will self-seal the wood. Second suggestion: clean the wood with acetone to take the oil and sap off the top layer of cells (the slime you were referring to is actually sap which has crystallized from exposure to air). Then seal with shellac. I do not finish my cedar and advise the customers to allow the furniture to breath for a period of time.
Another point to keep in mind is two out of ten have an allergy to ERC. In some cases, it can be severe. Ask your customers if they have an allergy to cedar.
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