Shelf life of finish

[Fred Perreault]

I was opening my 90% full gallon of boiled linseed oil to us in my concoction to seal my turnings today, and it smelled kinda funny. I have not used it in some time, and the can may be 3-4 years old. Does BLO, and Watco Natural Oil have a shelf life? Can it deacy, oxidize or otherwise turn bad?
Thanks for any info.....

[Roger Chandler]

I was opening my 90% full gallon of boiled linseed oil to us in my concoction to seal my turnings today, and it smelled kinda funny. I have not used it in some time, and the can may be 3-4 years old. Does BLO, and Watco Natural Oil have a shelf life? Can it deacy, oxidize or otherwise turn bad?
Thanks for any info.....


Fred, thanks for bringing this question to the forum. I would like to hear the answer to this and other finishes as well.

[Prashun Patel]

I have BLO that's 5-6 years old that dries fine. In theory, it can lose its ability to polymerize, but in my experience, if it doesn't skin over, it's usable. Danish oil and anything with varnish usually hardens if it gets unusable.

With any old finish, my test is to test it on scrap. If it dries (for BLO that would be within a day or so) I use it.

[Jim Sebring]

Shellac has a pretty short shelf life, even in undissolved flake form. See the current issue of Fine Woodworking for a great rundown on the stuff.

[John Keeton]

Fred, I think one must distinguish between BLO and other finishes. There was another thread (http://www.sawmillcreek.org/showthread.php?t=115548) last year on BLO, and the record for creekers was a 44 years on the shelf and still good!! I suppose it could become contaminated with some other substance, but so long as it remains pure, I don't think it goes bad.

Obviously, some of the other finishes do - Waterlox is notorious for a short shelf life - sometimes 2-3 months or less.

[Gary Max]

I have a 20 gal Stainsteel trash can that I make BLO homebrew in. It never gets less than half full.

[Prashun Patel]

In fact, I've had Waterlox go hard in the bottle after 2-3 days.

There are 2 keys to preserving finishes:

1) Keep the temp from getting too hot.
2) Minimize the oxygen in the container.

I can tell you that Boiled Linseed Oil is used by we in the fragrance creation industry precisely because it does develop an odor. It starts out fatty and leathery, and can develop a 'fishy' odor over time, which - unlike real fish - is not an indication of its unusability. The fish odor will disappear when the BLO is truly dry.

[Fred Perreault]

Thanks for the responses, folks. Of course it never occured to me to test the stuff on some scrap, as it was easier to let my keyboard to the work. The stuff did have an off scent, but it seems to change in the fresh air. And the viscosity seems okay, and there was no hardening nor skinning over in the cans. I'll see what happens in a few days with the test pieces. :)