Potassium dichromate

**ndy9691** · Jun-08-2008, 9:26pm

Hello everyone, # I've been searching the archives and havent turned up much on the topic of potassium dichromate.

My #question is : what do you use to mix this with, and at what ratio?
Is there anything else one should know before using this? i.e. vapors use gloves and so on.

Thanks for the replies # # #Dale

**austin** · Jun-08-2008, 9:31pm

You might want to check this out. Pretty nasty stuff....
msds potassium dichromate

**Bob A** · Jun-08-2008, 10:08pm

Seriously carcinogenic. Avoid it like the plague; or even more, we can cure the plague.

**MikeEdgerton** · Jun-08-2008, 10:12pm

You might look through these threads. The stuff is nasty.

**Joel Spaulding** · Jun-08-2008, 10:42pm

Originally Posted by (Bob A @ June 08 2008, 23:08)

Seriously carcinogenic. Avoid it like the plague; or even more, we can cure the plague.

We already can "cure" the plague. Yersinia pestis
is quite sensitive to gentamicin & doxycycline. Unfortunately my career-specific trivia knowledge does not make me a better mandolinist. #

- although I did learn this from a Mandolin-playing professor (Thank You Dr, Ken Record - for introducing me to this obsession!)

Completely agree with Bob and the others - unless you are just dying to use it, avoid it. (...as he ducks the thrown b#%j@s)

**Eddie Sheehy** · Jun-16-2008, 2:53pm

I've only ever used it mixed with phosphoric acid to make chromic acid. Used for cleaning brush-bristle debris from industrial diamond s... That was 30 years ago and so far so good, no extra limbs. Unless your mandolin is encrusted with diamonds I'd avoid it....and even then...

**rohan** · Jun-16-2008, 2:57pm

Real good at removing organic material from you glass eye. Don't have one? You will if you get this stuff in there.

**testore** · Jun-16-2008, 3:25pm

it's not too bad in a weak solution. Not sure the ratio, but I've used it for the last 20 plus years in water as a wood oxidizer when restoring violin edges with new wood. Put a little coffee on afterwards and you have a nice browm color. Great for coloring violin necks too.

**Zigeuner** · Jun-17-2008, 11:23pm

Originally Posted by (testore @ June 16 2008, 13:25)

it's not too bad in a weak solution. Not sure the ratio, but I've used it for the last 20 plus years in water as a wood oxidizer when restoring violin edges with new wood. Put a little coffee on afterwards and you have a nice browm color. Great for coloring violin necks too.

Yes, I used it in a weak solution as well.

Back in the 1970's I built 9 steel string guitars. I used honduras mahogany for the necks on all of them and African Mahogany on a few of the bodies. The other bodies were Brazilian Rosewood.

I learned about using potassium dichromate as a wood stain from my brother who was a chemist at one time. I got a small bottle of the crystals from a chemistry supply in Los Angeles. I mixed it to an approximate 5% solution so that the color was a pale orange. I still have an almost full bottle of crystals and another larger bottle of mixed solution.

Once the mahogany parts were ready for finishing, I used a spray bottle to soak the wood completely. After drying, it will have taken on a toast-like appearance. If you want it darker, you simply give it one or two more applications. Once the wood is dried out, you can use sealer and any type of finish you wish.

The benefits are that it works in a very progressive manner and leaves no oily residue. The wood will be completely dry and ready to go once the moisture has dried out.

I used it most recently a few years ago when I restored a Gibson 12 String B-25 that was missing 90% of it's finish when I got it. It came out with a nice even brown color.

These were guitars, of course, but the application to mandolin building would be exactly the same where mahogany is involved. I don't think it has any effect on light woods like maple or birch.

As others say, it's a poison and must be handled accordingly - use eye protection, rubber gloves and proper marking and storage on the bottles. I've done that and have had no difficulties. It's really economical by the way as it looks like one bottle of it would last you a long time.

**HoGo** · Jun-18-2008, 8:23am

One should keep in mind that Potassium dichromate is not poisonous in sense of Gamboge e.g. when you drink some of it you'll die... It's cumulative carcinogen... it will cumulate in your body for long periods fo time and once in the future it CAN kill you in form of cancer.
Spraying it is especially hazardous as the overspray is all over the place.
On the other hand you can use potassium permanganate that is completely safe (used in healing of some skin deseases) and colors the wood similarly, even without risk of "burning' the wood.
Just my $.02

**Zigeuner** · Jun-18-2008, 12:04pm

Originally Posted by (HoGo @ June 18 2008, 06:23)

One should keep in mind that Potassium dichromate is not poisonous in sense of Gamboge e.g. when you drink some of it you'll die... It's cumulative carcinogen... it will cumulate in your body for long periods fo time and once in the future #it CAN kill you in form of cancer.
Spraying it is especially hazardous as the overspray is all over the place.
On the other hand you can use potassium permanganate that is completely safe (used in healing of some skin deseases) and colors the wood similarly, even without risk of "burning' the wood.
Just my $.02

Yes, you could use petasium permanganate. IIRC, though, it's rather purplish in color. It doesn't give the nice toast brown like p. dichromate does.

**Geoff B** · Jun-19-2008, 11:30am

why not just find/make the right color brown dye? I used K2Cr2O7 once and was got freaked out by the danger level- super strong oxidizer, carcinogenic etc. I guess it does antique the wood a bit, but if you just want a brown color, use a dye...

**Zigeuner** · Jun-19-2008, 12:03pm

Originally Posted by (Geoff B @ June 19 2008, 09:30)

why not just find/make the right color brown dye? #I used K2Cr2O7 once and was got freaked out by the danger level- super strong oxidizer, carcinogenic etc. #I guess it does antique the wood a bit, but if you just want a brown color, use a dye...

If P.D.'s poisonous nature bothers you, I agree that you should use something else. In use, however, if the necessary precautions are used, there is no problem.

I used to use alcohol-based wood dyes and they are OK. The P.D. was much more gradual and a lot easier to use. Denatured alcohol is also a poison.

**HoGo** · Jun-20-2008, 6:52am

Originally Posted by

Yes, you could use petasium permanganate. IIRC, though, it's rather purplish in color. It doesn't give the nice toast brown like p. dichromate does.

Permanganate is purple when dissolved but it colors to antique amber to brown depending on concentration and number of applications. In combination with tea the color can be richer. Dichromate in strong solution will burn the wood to greenish brown that is REALLY ugly.
Give it a test on a scrapwood. It's cheap and available at pharmacy.

**Zigeuner** · Jun-20-2008, 11:53am

Originally Posted by (HoGo @ June 20 2008, 04:52)

Originally Posted by

Yes, you could use petasium permanganate. IIRC, though, it's rather purplish in color. It doesn't give the nice toast brown like p. dichromate does.

Permanganate is purple when dissolved but it colors to antique amber to brown depending on concentration and number of applications. In combination with tea the color can be richer. Dichromate in strong solution will burn the wood to greenish brown that is REALLY ugly.
Give it a test on a scrapwood. It's cheap and available at pharmacy.

I don't disagree with your take on P.D. I never used it in a strong solution. Of course, it's an oxidizer and a very strong solution would certainly burn the wood.

As you must know, a guitar (or mandolin) builder needs to have a whole group of techniques available to him or her. Potasssium dichromate or potassium permanganate are just two of a whole list.

I'm getting the idea that you don't lke Potassium Dichromate. I first used it nearly 45 years ago and have had absolutely no trouble with it under any circumstances. It's like any other dangerous substance used by humans, such as gasoline, lacquer thinner, nitrocellulose lacquer, shellac, acetone, plutonuium, uranium and anythng else.

If you think potassium dichromate is to dangerous to use and handle and don't like it, then by all means, stay awzy from it.

**Bill Snyder** · Jun-20-2008, 8:22pm

Originally Posted by (Zigeuner @ June 20 2008, 11:53)

... It's like any other dangerous substance used by humans, such as gasoline, lacquer thinner, nitrocellulose lacquer, shellac, acetone, plutonuium, uranium and anythng else. ...

I don't think shellac really belongs on that list. If you use EverClear in mixing it, you can drink it with no more danger than drinking EverClear.

**Zigeuner** · Jun-20-2008, 9:27pm

Originally Posted by (Curious @ June 20 2008, 18:22)

Originally Posted by (Zigeuner @ June 20 2008, 11:53)

... It's like any other dangerous substance used by humans, such as gasoline, lacquer thinner, nitrocellulose lacquer, shellac, acetone, plutonuium, uranium and anythng else. ...

I don't think shellac really belongs on that list. If you use EverClear in mixing it, you can drink it with no more danger than drinking EverClear. #

Excellent point. I will have to take your word for this. Mind you, I don't doubt your word, it's just that drinking shellac with a mixer of absolute alcohol is rather unusual.