Hi,
I am from South Africa and want to venture into the Greene & Greene style of furniture. I am going to use African Mahogany wich is readily available. I have read in the media that potassium dichromate will color the mahogany to a reddish brownish color. The problem is that i can not find this potassium dichromate anywhere in this country. Is there a a different potassium that can do the job, or any other method.
I would appreciate any help in this regard
Thanks
Replies
hey nollie,
could you not use commercial wood dyes instead?
eef
just did a google search and the 6th one down the list mentions the mahogany reddening properties of the stuff. it goes on to say that it's pretty nasty and toxic and perhaps dyeing the wood might be a better choice.
good luck,
eef
Edited 11/25/2009 2:28 pm ET by Eef
This doesn't really answer your question, but pottasium dichromate is used in the photographic development process, so maybe a top line photograpy shop migh have it. I hear it's nasty stuff - be careful.
I've done a similar "ageing" of mahogany using lye I made from fireplace ashes. It was a long time ago and as I recall, the lye just darkened it, it didn't bring out too much red. I think drain cleaner will do the same thing, but I didn't know how that might affect adhesion of my top coat. By the way, lye is pretty nasty stuff too.
Potassium Dichromate is a laboratory chemical and should be available from a laboratory chemical supply house. I doubt that there is an alternative chemical for what you want to do. However the advice to try a dye is sound. Otherwise:
Ask a Chemistry teacher or someone who works in a lab for a source.
Wear gloves and, if you sand the treated wood take extreme measures againt dust inhalation. I assume that you are a sensible adult.
Ironically Potassium dichromate occurs naturally in South Africa!
Amazon offers it through Adorama.
http://www.amazon.com/Photographers-Formulary-Potassium-Dichromate-grams/dp/B000B73OBO
No idea what duty and shipping will run you. Best of luck.
Try caustic soda. You can probably find it in the plumbing section of your local hardware store. It can be used to help unclog drains, clean porcelain and take grout off tiles!
Be EXTREMELY cautious with this stuff where heavy rubber gloves a breath mask and use eye protection and what ever you do don’t get it on any thing except what you intend to! Use it in a well ventilated area! Rinse the wood with water to stop the chemical action!
Chaim
Nollie,
I'm not sure what color Greene & Greene furniture is, but you might try Hydrated Lime (used for gardening) or lye (sodium hydroxide) . Lye is used to make soap, and it is also a component of some drain cleaners. The problem with the drain cleaner is not all drain cleaners are 100% lye, so you have to read the label. The lime is fairly easy to use and results in a great color, that is very light fast. Lye is even easier to use, but it is more dangerous. Lye also develops a nice stable color.
Rob Millard
http://www.americanfederalperiod.com
Edited 11/25/2009 8:11 pm ET by RMillard
Edited 11/25/2009 8:12 pm ET by RMillard
Thanks Rob . I will try some lime or sodium hydroxcide wich is readely available.
Nollie,
I just happen to be where I could take a photo of a piece of mahogany treated with lye some 10 years ago. I adjusted this for color (that is what the gray card is for) and it looks right on, on my monitor. The lye gives a more brown color than the lime does.
One leaf of this table is folded against the wall but the other 2 are exposed to a large south facing window, and there has been no fading or color shift in those 10 years. The apparent shift between the two leaves, is from the one leaf dropping down slightly and the light hitting it at a different angle.
I don't remember the lye to water ratio I used, so you'll have to try it out on scraps. I did not neutralize the lye with anything. I just let it dry completely before putting on some Danish oil and shellac. I have since used the lye on cherry and following with a wash of white vinegar improved the color, so you may want to try that on mahogany just to see what it would do.
Rob Millardhttp://www.americanfederalperiod.com
Edited 11/26/2009 8:51 am ET by RMillard
Hi,
I got hold of some sodium hydroxide. My first attempt was not as good , it came out to brown. So i decided to make a very weak solution and bang , spot on. The colour is a reddish colour . The exact colour that i wanted. I sealed it with Danish oil ( 4 coats ) and it looks lovely. I will take a picture tomorrow and post it.
I tried the solution on other mahogany's (burmog,south american,sapele) with no luck. The colour darkens only , but do not turn red. Only the african mahogany turns red.
Thanks again for all the help from every body
Nollie,
I'm glad you found a water to lye ratio that gave you the right color.
I have used it on South American mahogany to good effect. In fact the photo I posted was of it on SA mahogany. I guess it just goes to show how unpredictable chemical coloring can be.
Rob Millardhttp://www.americanfederalperiod.com
http://www.woodfinishingenterprises.com/dyes.html
N
This is where I get mine. Don't know about shipping to SA??
Like others have said, you might be able to get the results you want with dyes. Its kind of hard if you don't know what color you get with PD.
How do you match the dyed wood to the PD color.
Note: mix small batches of the PD. It goes a long way.
I have used a nitric acid and water mix with iron filings to make curly maple pop like ... a bunch. Others have said "you can do that with dyes" ?? Well I can't and I can get a depth with chemicals I can not achieve with water dyes. Sometimes one works better for what you want than others. You just have to experiment a little and learn a new skill.
Truthfully, I have used the PD and gotten myself too red. I washed on some green dye and back it came to a brown. So a combination can work.
dan
Edited 11/27/2009 5:27 pm ET by danmart
Several years ago my wife and I attended a class at Ben Hobbs', http://www.hobbsfurniture.com, in North Carolina.
We both made end tables, and I used potassium dichromate (p.d.) in my finishing process.
Upon returning home, I tried to find p.d. at all of the local pharmacies, with no luck.
I then found out how toxic p.d. is.
I have also learned that Ben no longer uses p.d., but now uses aniline dyes (his son Calvin posted this info here). I would contact Jeff Jewitt, http://www.homesteadfinishing.com, for advice.
Hope this helps.
Pete
There's an African "Mahogany" called Khaya in the US that darkens quite a bit with exposure to strong sunshine. I think some of the other species sold as African Mahogany do the same thing. You might be able to avoid the strong chemicals entirely, depending on which species you're using.
Thanks . This is the same mahogany that you have. I will try the sunshine . The easier the method the better.
Thanks
I'm pretty sure they used Aqueous Ammonia in a tent to darken the quartersawn white oak. i believe it's available at pool supply dealers.
I have also seen recipes for rusty parts soaked in white vinegar, filter out all the debris and apply to wood and it us used to ebonize.
commercial wood bleach is made up of part a and part b.
One is Hydrogen Peroxide[a strong oxidizer] the other is Sodium Hydroxide.Sodium Hydroxide, when used by itself will darken the wood.
If you use the NaOh make sure, and this also applies to mixing the a+b together to bleach,that you find out the neutrelizing agent.Typically it is baking soda for one and white vinegar for the other. I will get that info. correct if you or others decide to try any of these. rob
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