What causes honduran mahogany to darken with age?

[Mac Walker]

Is it oxidation, UV exposure, moisture related, or have anything to do with the type of finish applied?
Just wondering if anyone knew of any way to get the wood to darken naturally BEFORE finishing. Of course I can grain fill with a dark grain filling material. Just wondering if anyone has had any experience with this in a solid body (or backs & sides) application....

Thanks.

[Penql]

Oxidation is a big part of it. You can darken it with a solution of lye (Drano) and water, let it penetrate a while (wipe on with wet rag, sit 10-15 mins, dry off, use gloves!), you'll be sanding off raised grain afterwards. Experiment!

[Bob Webster]

Yes, it is oxidation. Another favorite way of darkening mahogany is to treat it with an aqueous solution of potassium dichromate, a strong oxidizing agent. I think it can be bought from some specialty woodworking places and it does a great job. I'm sure there are directions for this app on the web but it's really pretty simple. The solubility of the material in cool room temperature water is not very high so I just throw some in a glass, throw in some water and stir until it seems that no more will go into solution. Then, wearing gloves, I wipe it on with a piece of cloth. Darkening is virtually immediate and the grain will be raised in this step. After sanding back, you may sand through some of the darkened wood so a second treatment is usually needed to get a uniform stain. And, as Penql already said, experiment!

Cheers,
Bob

P.S I've only done this on mahogany. It might work on some related woods but I wouldn't know.

[Rob Mercure]

This method works really well but, as I was taught, is usually used to bring out the figure in a plain piece of mahogany. Probably what you want but wanted to let you know just in case you're trying to match something darker but less figured. Got a library handy? Almost any book on wood working that deals with coloring/staining wood will go into this - if mahogany isn't specifically noted look at the entries for darkening oak as it is the tannins (complex poly-phenols) in the woods that react with iron and other compounds to darken wood or change it's color.

Rob

[Mac Walker]

Thanks for the info.

I see that the potassium dichromate is listed as a class I carcinogen (yikes).

Maybe I'll start with the hydroxide since I've already got some under my sink.

My first thought was to get one of those pure oxygen bottles like athletes use, but I tend to overthink these things sometimes......

[Penql]

If you really want to have some fun, you can use ammonia fumes - you want anhydrous ammonia full strength, and possibly a hazmat suit. I've done this sans suit, which is why I mention it. Beautiful color though.

Drano is faster. :)

[Bob Webster]

Wikepedia has a list of Class I carcinogens. Included on the list are such things as alcoholic beverages, wood dust, Chinese style smoked fish, solar radiation, mineral oils, and betel quid. Class I materials represent the lowest risk among those known to cause cancer in humans and requre rather substantial exposure to initiate carcinogenesis.

Tannins actually react rather slowly to pure molecular oxygen and the process is probably catalyzed photochemically. I think I'd rather put on some gloves and use the dichromate than try to use either pure oxygen or deal with anhydrous ammonia unless, of course, you live in a chem lab.

Cheers,
Bob