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  1. #11
    titrisol's Avatar
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    It should work, k-oxalate solutions have excellent dielectric properties so it should heat up faster than plain water.
    Try 1/2 the time you'd use with water as a start point
    Mama took my APX away.....

  2. #12

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    There's another reason to keep a lid on the PO at all times. I've been told that it is quite corrosive, so you will probably want to avoid getting any into the air, where it can start to work on the metal in your darkroom.

    I don't know if this is true, but I figure it's better to take a few precautions.

    ---Michael
    www.mutmansky.com
    B&W photography in Silver, Palladium, and gum bichromate.

  3. #13
    titrisol's Avatar
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    According to the MSDS the powder seems to be a lot more toxicn tahn solutions of it.
    It is not volatile, but the powder can be fine, a granular type would be better to minimize those risks:

    J.T. Baker SAF-T-DATA(tm) Ratings (Provided here for your convenience)
    -----------------------------------------------------------------------------------------------------------
    Health Rating: 3 - Severe (Poison)
    Flammability Rating: 0 - None
    Reactivity Rating: 1 - Slight
    Contact Rating: 3 - Severe (Corrosive)
    Lab Protective Equip: GOGGLES; LAB COAT; PROPER GLOVES
    Storage Color Code: White (Corrosive)
    -----------------------------------------------------------------------------------------------------------

    Potential Health Effects
    ----------------------------------

    Inhalation:
    Inhalation of dust is corrosive to mucous membranes. Oxalates can be absorbed through the lungs. Symptoms of poisoning include nervousness, cramps, central nervous system depression.
    Ingestion:
    Mean lethal dose for oxalates in adults is estimated at 15-30 grams with death within a few hours or even minutes. Corrosive action on the mucosa and severe gastrointestitis can occur with pain, vomiting, etc. Sharp reduction of serum calcium can cause disfunction of the brain. Calcium oxalate may be deposited in the kidneys.
    Skin Contact:
    Corrosive. Symptoms of redness, pain, and severe burn can occur.
    Eye Contact:
    Corrosive. Contact can cause blurred vision, redness, pain and severe tissue burns. Prolonged contact may cause eye damage.
    Chronic Exposure:
    Circulatory failure or nervous system irregularities may follow prolonged calcium metabolism disturbances due to oxalation.
    Aggravation of Pre-existing Conditions:
    Persons with pre-existing skin disorders or eye problems, or impaired liver, kidney or respiratory function may be more susceptible to the effects of the substance.


    I wouldn't heat with the lid on, but in a half full container, there's less risk this way because when you microwave with lid on vapours are promoted.
    Last edited by titrisol; 11-02-2004 at 03:00 PM. Click to view previous post history.
    Mama took my APX away.....

  4. #14

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    I like to use one of those coffemug warmers. It's like a little hotplate that holds a mug sized container. I just sit the bottle on it and leave it there warming up and staying at the same temperature for the session.

    Not sure what temperature it got to exactly, but was warm.

    joe

  5. #15
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    I decided to test k-oxalate in the MW oven for myself.
    First I measured dielectric properties of 0.1, 0.5, 1, 2, 5 and 10% solutions

    Increasing the concnetration of k-ox increases the "loss factor". Thus, heating is more efficient at higher concentrations.
    A 1% solution will heat 3 times faster than water, and a 10% solution about 5 times faster.

    In an old crappy box I have here (it's almost shot), I was able to heat 1 cup (250 ml) of 1% solution from room temp (about 25C) to 80C in about 1:00. In a household MW box, it should take about 20 sec

    So beware of the speed of heating, and start with short times. Use a half empty container to heat, it'll avoid spills.
    Mama took my APX away.....

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