(This one is actually a product for sale for WOOD surfaces!) http://www.abso.com/woodcoatings/patina/6000.html
And this article, which I thought was really interesting, (I might have to try this myself!) Good Luck!
Posted by Bruce Paul Fink on January 10, 1998 at 22:04:06:
Two of my most favorite wood patinas originated in old Europe. As an occassional wood worker of whatever and with 120 acres of woods to choose from... even a metal casting sculptor has wood as an important part of life. I often don't agree with the concept of staining it to make a substance look 'more like itself' while masking its real nature. Each tree has it's personality, growth history and visable cycles of stresses and I enjoy being sensitive while reading and feeling its newly exposed form with its growth history remaining evident.
Formula #1 is simple Drano, lye, or sodium hydroxide mixed with water. Wear rubber gloves and act as though you were cleaning the toilet. Proportions vary but never over about 50%. This has to be put on (I brush with a cheap bristle brush as it dissolves some bristles and ages all the rest) with a wet flowing sweep from top to bottom as it immediately burns the tanic acid in the wood and Heaven erupts. Cherry wood brightens to the brilliant bright reds it will get usually only after years of exposure while still leaving any of the outer tree wood it's lighter tans. Oak will go from fresh natural to darker yellow to dk brown. Again the tanic acid is causing the change so the wood develops a patina that is truely aged without stress or masking a tone to the knots.
Formula #2 is similar in its effect but will take maple or even light woods to a richer brown or even an ebony black. This is composed of apple cider vinegar and iron fillings put together and covered but not tightly capped (could blow apart the bottle). Leave for several days or longer and then brush or spray on. The change again is almost immediate. Trim and an active maple step that leads out of the abused firewood bin is constantly rubbed, scratched and abraided but still holds true to its initial finish of 22 years ago and still is believed by the unknowing to be an exotic black wood. "You didn't cut this tree here. Maybe, no, that's not really Ebony then is it?" The tanic burn is not only surface but moves in and acquires a depth to protect. Finish is a clear satin laquer or urethane varnish and these days a water based urethane is my preferred choice.
As one with an owner designed and built 22 year old green wood house the grains and qualities are outstanding if I say so myself. The question of the stain seldom comes up however unless the viewer is one who also stains, then it's nearly inevitable. This tanic acid burn is not effective on low tanin based woods so pine or fir or... forget it.
This is an ideal finish for wood sculpture as it reads wood through and through. If nothing else you might like to try this on a scrap just as a magic act... and as the sun sets in the west. email@example.com