Why do old stock finishes turn black?

[4V50 Gary]

I'm using vegetable based soap and cotton rags to clean an old rifle. Scrubbed the white spots (mold?) off and then some of the dust and grease. Why do old stocks turn black? After scrubbing, I can see the grain again and more rubbing and the old sheen comes back.

 

[ttarp]

Isn't it oil seeping down from the action while they sit in the safe?

 

[Scorch]

Boiled linseed oil turns dark as it oxidizes, and gets a very distinctive smell to it. I hate the smell and the look, I strip it off at the first chance I get. Many old timers will swear by linseed oil to preserve wood. Probably the worst thing for wood, but it's kinda like neat's-foot oil on boots, "it was good enough for gramma, it's good enough for me". BLO will lift off varnish by swelling the wood fibers below it then make the varnish crumble. Then it turns dark. Worst part is, it does nothing to preserve the wood or seal the wood against moisture. But by stripping it and refinishing, I have found some really pretty stocks under boiled linseed oil!

 

[James K]

Oil. Sweat. Dirt. Not necessarily in that order.

Jim

 

[mete]

Linseed oil both polymerizes and oxidizes in time ,both turn it darker.

 

[Dixie Gunsmithing]

UV light can cause a breakdown in a lot of old finishes, and affect the color. Even things like humidity, air pollutants, etc, can cause changes. That is why the have all those additives in finish these days.

Darkened wood, under the finish, is generally caused by oil. This mostly shows at the front of the grips on stocks, and the cure is bleach. The cause is people over-applying oil to a gun, and when stored upright, it drains to the rear of the receiver, and soaks into the end grain of the stock where it meets. That can also cause changes in the wood, and cause it to split. When finishing/refinishing a stock, I always apply at least one coat of finish to the end grain that mates with the receiver to seal it.

 

[Mosin-Marauder]

My Remington 514 had Linseed Oil on it and my Shotgun. Awful stuff. Looks ugly and and smells awful. A pain to get out aswell. Leaves spots in the stock.

 

[rrruger]

I refinished a lot of furniture that has darkened with age. Some white oak pieces turned Black after 100 years. On stripping the finish the bare wood was much lighter.

 

[Huffmanite]

Traditional varnish will certainly darken to almost black. Been a number of times I've used some form of finish restorer, Formbys for example, on a very old piece of furniture, to soften and remove much of the old varnish.....leaving me with a really nice and much lightened wood.

 

[Gunplummer]

Huffmanite pretty much said it. How many finishes were around for gun wood way back? Think about cars before the 50's. Not much color there. I would say the two main wood finishes for older furniture were varnish and shellac. Both seem to darken with age, or dirt and oil?