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Thread: Potassium Dichromate on Mahogany Cameras

  1. #11

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    Re: Potassium Dichromate on Mahogany Cameras

    Using it for one project will not cause over exposure. Just wear gloves and use it in a ventilated area. I wouldn't recommend using an oil finish unless it has driers in it.
    I have a lot of experience using it on Mahogany but I've always used shellac as a finish. The real problem is if you don't have experience applying it you could end up with uneven areas.

  2. #12
    Mark Sawyer's Avatar
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    Re: Potassium Dichromate on Mahogany Cameras

    I'm not so much worried about the exposure during application, as precautions can be taken. It's more the handling after the camera is built. As in, after drying and darkening the wood, should I wipe it down with a damp rag before finishing? And would a water-based polyurethane finish provide sufficient protection for long-term handling?

    From what I've read, it's much easier to get an even, non-blotchy finish with potassium dichromate than with conventional solvent stains. I'm still caught between the two...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  3. #13

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    Re: Potassium Dichromate on Mahogany Cameras

    Won't other safer chemicals give you the same look? Do a search on ebonizing wood.

  4. #14

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    Re: Potassium Dichromate on Mahogany Cameras

    Quote Originally Posted by Mark Sawyer View Post
    I'm not so much worried about the exposure during application, as precautions can be taken. It's more the handling after the camera is built. As in, after drying and darkening the wood, should I wipe it down with a damp rag before finishing? And would a water-based polyurethane finish provide sufficient protection for long-term handling?

    From what I've read, it's much easier to get an even, non-blotchy finish with potassium dichromate than with conventional solvent stains. I'm still caught between the two...
    No do not wipe it with anything, it is ready to be top-coated. I don't have much experience with water based finishes. I would consider a solvent based finish. After the first thinned coat you will have to sand lightly.
    When applying the PD use a brush. It's difficult to explain but you don't want to wet a portion and let it soak in without doing the whole area because repeatedly wetting it will cause it to become darker. So avoid that by working one area quickly and moving on. Cameras are not big so you shouldn't have a problem.

  5. #15

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    Re: Potassium Dichromate on Mahogany Cameras

    It'll be fine after it's applied. I do a lot of gum printing. While the potassium dicrhomate is pretty dangerous in crystal and liquid form, the gum print itself isn't dangerous once it's dried. If your oxidizing wood with it, just be sure to wipe off any excess after your done and give it time to stabilize. Sealing the wood be a good idea as well. Once the wood stabilizes, it should no longer pose a threat. It breaks down during the oxidation process. They use this stuff in commercial concrete as well. The main danger is when you're applying this stuff.

  6. #16
    Tim Meisburger's Avatar
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    Re: Potassium Dichromate on Mahogany Cameras

    For what you want it for, I don't think it will cause you any problem. You can also stain mahogany with lye, or lime, in solution. Lye is caustic, so you need to use care, but I use it without much worry to make soap.

  7. #17
    Mark Sawyer's Avatar
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    Re: Potassium Dichromate on Mahogany Cameras

    Quote Originally Posted by el french View Post
    Won't other safer chemicals give you the same look? Do a search on ebonizing wood.
    Ebonizing is sort of the same, an iron-based oxidizing, as I understand it. But I don't care for the cold greyish-brown to black tones.

    Quote Originally Posted by chris_4622 View Post
    No do not wipe it with anything, it is ready to be top-coated...
    Quote Originally Posted by jim10219 View Post
    ...just be sure to wipe off any excess after your done and give it time to stabilize..
    Oh, you guys are a big help!

    I'm guessing it's okay to use carefully, I just wish there were some reliable info on how it breaks down over time. That chromium must still be there somewhere...
    "I love my Verito lens, but I always have to sharpen everything in Photoshop..."

  8. #18

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    Re: Potassium Dichromate on Mahogany Cameras

    I guess I started this. I told Mark that I like the way it works, having used it some on mahogany. I don't know where I read it, but did read that most mahogany furniture used it for generations. Since in America mahogany was the most popular wood for furniture in the 18th and 19th centuries, I have to believe generations were eating off of it, playing cards on it, laying across pianos made of it.

    I didn't think about it when I used it after brushing it on and letting it dry. I think rubbed oil on it. Yes, rubbed. Maybe a mistake, but I have a feeling if furniture makers were doing this for entire careers, a couple times won't hurt. You do hear about miners, assayers, and occasionally daguerreotype photographers getting sick from mercury poisoning. That was probably a worse substance.

  9. #19

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    Re: Potassium Dichromate on Mahogany Cameras

    I remember seeing that mortality rates for people working with hard woods (specifically mahogany and walnut) in the days before the mechanical removal of dust were pretty awful and specifically linked to cancer of the air passages. So any problem with dichromate would have been masked. I think the problem is of the same order as Thorium in post WW2 lenses - just show due caution in reworking the wood surface - the Chromium is still there.

  10. #20
    Tim Meisburger's Avatar
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    Re: Potassium Dichromate on Mahogany Cameras

    After researching this, I ordered some to use on the camera I'm making

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