Oil finish v. Polyurethane

[JustRob]

Is there a quick way of determining whether a stock has a linseed oil v. articifial finish? I'm evaluating a used musket and while the stock looks good and is very similar to the oil finishes on my other muskets, I'd like to be sure.

Thanks in advance for your replies.

[rogue]

Re: Oil finish v. Polyurethane

Rob,
Get a blow torch, light it, and apply it to the side of the stock, opposite the lock.
If the wood chars then burns, it is oil finish.
If the finish bubbles and smells like burning plastic, it is.
Steve Sullivan :D

[Curt Schmidt]

Re: Oil finish v. Polyurethane

Hallo Kamerad!

There are a number of "Heinrich Home Tests" on can perform to get a decent "idea" of what was used on the wood ranging from commercial "indicators" such as "Dr. Dan's Finish Indicator" (from Star Woods) to these:

1. Apply a few drops of water to a flat surface such as the butt. Come back in 10-20 minutes. If the water has been absorbed (linseed oil is hygroscopic), or whitish spots remain- it is likely an "oil finish." If the drops are still there, it is "poly." (Noting many so-called "linseed oil finishes" or "oil finishes" are part varnish, or have hardening agents and drying agents added.)

2. Rub a few drops of boiled linseed oil into the wood. If it gets absorbed-the wood has an oil finish. If it "beads up," it has something else (a "hard type" finish).

3. Rub acetone over a small spot in a gentle, circular motion. Polyurethane finishes shed acetone like water. A lacquer finish dissolves in a minute or less with rubbing. Varnishes and shellacs turn to a sticky, gel-like substance after a minute or two.

4 Rub a little denatured alcohol over a small spot. A shellac dissolves rather slowly in denatured alcohol. A varnish finish reacts rather slowly.

Unless one is interested in refinishing the entire stock, it may be best to pick an "out of the way" or "out of sight" location to test. :-)

And, if the finish by chance (or by design) looks like a period hot-dipped linseed oil finish to begin with, how much does it matter whether it is "modern boiled linseed" or something else in the end? ;-)

Most lads simply apply say 4-6 rubbings of "modern boiled linseed oil" and call it both "close enough" and a "day." It is hard to sand, abrade, or tone-down "poly" to look like anything else but "poly." So, IMHO, if it does not look like "poly," it is likely something else. ;-)

Curt-Heinrich Schmidt