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Something learned
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=1757
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Author:  John How [ Fri Apr 22, 2005 3:16 am ]
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I learned a new trick last night that someone may find usefull, though it didn't fit my needs.
I was looking for a way to darken some mahogany (safely) and read that iron oxide will darken the tannin found in some woods and that tea can be used to add tannin to woods that don't have much. Ayway I applied a coat of strong tea to some mahogany, let it dry and then soaked some steel wool in vinegar to make an iron oxide solution. After I brushed the solution on it get dark, in this case real dark, completely black. So if you wan't to turn wood black, I found a good way. Glad I tried a sample first. I will experiment with a diluted solution tonight to see if I can get the color I want. Also I found that mahogany must have quite a bit if tannin in it naturaly becasue even without the tea it turned pretty black. Any chemests out there care to comment?

Author:  Jeff Doty [ Fri Apr 22, 2005 3:18 am ]
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John,

Can you take a picture? Before and after would be wonderful. Hope you have another scrap you can try it on.

Jeff

Author:  John How [ Fri Apr 22, 2005 3:21 am ]
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If I get it to do what I want I will take some pics but as it worked last night it looked like the kind of ebony that you don't get much anymore (Black) with a mahogany texture.

Author:  Mario [ Fri Apr 22, 2005 3:23 am ]
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Next test is to leave it in the sun a few weeks to see if it is colorfast or not. Don't assunme that it will automatically hold the color. Test!

Author:  John How [ Fri Apr 22, 2005 3:30 am ]
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Yes, this is true. And maybe the iron will rust and turn just the right shade.

Author:  PaulB [ Fri Apr 22, 2005 11:33 am ]
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It will hold the colour, and you can have any colour you like as long as it's black.

This stuff is known as liquid nightmare, or rusty nail brew. A bunch of old nails or bits of iron in a jar covered with a 50/50 mix of water and cider vinegar, leave it for a few weeks, then strain and bottle.

It won't work on all woods. But if you put on a coat of Tannic acid (5% Tannic acid to 95% hot water) before the rusty nail brew and let it dry, it should work on all woods. This is the same kind of thing as using strong tea. There is also a product in the US called logwood extract that you can use instead of the tea, or the (toxic) tannic acid mixture.

Chemically, it's same reaction as when you get that black stain around nail holes in oak, and that stuff doesn't fade.

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