Thiocarbamide - Safety and image tone

Discussion in 'B&W: Film, Paper, Chemistry' started by Tom Stanworth, Jul 31, 2005.

  1. Tom Stanworth

    Tom Stanworth Member

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    I have used this variable tone toner a fair bit, but saw a comment on the web a few days back suggesting that this (thiocarbamide component) stuff is especially poisonous. I realise all chems should be treated with care, but is this something to be especially....doubly, triply careful with?

    Now onto using it 'Cold'. What difference does this make? Is is just a colder image tone and the converse true if it is 'warm'? I have always used at room temp and not given it much thought as I have used little in the last few years.

    Tom
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Thiocarbamide is commonly known as thiourea, a sufur derivative of urea.

    Thiourea is produced naturally by several plants, and has recently been discovered to have some toxic effects and is a suspected carcinogen. OTOH, it has been used in photography and other areas for at least 100 years, and only recently has come under scrutiny.

    It is known to fog film and paper, so if you do use it, make sure you clean up and don't get the dust on anything.

    PE