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  1. #1

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    Pyrocat-P in glycol

    I'm getting ready to mix up a new batch of part A in glycol for the first time. I have always used water before. My question is in regards to the P-Aminophenol. Can it be mixed in the glycol, or does it have to be mixed in water like the bromide and soduim metabisulfite? Also can the glycol be heated in the microwave?
    Thanks,
    John

  2. #2

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    You don’t need to mix P-Aminophenol in water – it will go into solution in glycol quite easily.

    I will stay away from discussions on glycol and microwave ovens – but it has been discussed here: http://www.apug.org/forums/forum37/4...chemicals.html

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    Thanks, All my questions have been answered. I guess it's off to get a hotplate, as I have a gas stove.

  4. #4
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    You cannot mix the sulfite in glycol. Substitute some ascorbic acid. I forget how much, but it's not much. The sulfite in Pyrocat activates the superadditivity between catechol and p-aminophenol. A small amount of ascorbic acid will serve as well.

    You have not seen the latest about heating glycol. If you use a Pyrex saucepan and cover it with Glad or other brand of microwave-safe plastic wrap, and leave enough slack so that the wrap rests on the surface of the glycol, you can see the instant boiling begins and remove the saucepan from the stove. That temperature is very much higher than you will need. No vapor can arise from the surface without lifting the plastic, and none can overflow the container without breaking the seal between plastic wrap and container. If you heat the glycol container in a water bath, or use a double boiler, you will not be able to boil the glycol until the water boils away, if then. The only purpose of the heating is to speed up the dissolving by reducing the viscosity and increasing the molecular motion. If you have a stirring device, magnetic or other, and can wait long enough, lukewarm will do.
    Gadget Gainer

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    Got-R-done. I stopped by the thrift store to see if they had a hotplate. Then I noticed a 1Qt rice cooker with an aluminum insert. It worked great. Constant stirring with a thermometer in the glycol took maybe 5 minutes at the most, then I removed the insert from the heat, and mixed. The rice cooker cost $7.50

  6. #6

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    Quote Originally Posted by gainer View Post
    You cannot mix the sulfite in glycol. Substitute some ascorbic acid. I forget how much, but it's not much. The sulfite in Pyrocat activates the superadditivity between catechol and p-aminophenol. A small amount of ascorbic acid will serve as well.
    John,

    If you mix Pyrocat-P in glycol, and I highly recommend that you do as the p-aminophenol version of Pyrocat appears to not keep as well as the metol and phenidone versions, you can do one of two things.

    1. Mix the sodium metabisulfite in a small amount of hot water to dissolve, and then add to the glycol solution,

    or, and this is best,

    2. Substitute 4 grams of ascorbic acid (per liter of developer) for the sodium metabisulfite.

    The working characteristics are virtually identical, whether you do #1 or #2.

    The version that uses ascorbic is called Pyrocat-PC, for obvious reasons. With stirring all of the chemicals of Pyrocat-PC dissolve readily in warm water at 120-150F.

    Sandy King

  7. #7

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    Thanks Sandy,
    That is why I did the developer in glycol this time as my last liter didn't last through use, whereas the HD version did. I mixed the sodium bisulfite with 50cc of water before I started heating the fluid and had other measures already laid out in coffee filters. I will try the PC version next time. Will the results be like -P or -HD? I prefer the -P. My results indicated that the mid range didn't stretch out as much as -HD when doing N+. Plus the grain structure is different than -HD. I also highly recommend the rice cooker route.
    John

  8. #8

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    Quote Originally Posted by vet173 View Post
    Thanks Sandy,
    That is why I did the developer in glycol this time as my last liter didn't last through use, whereas the HD version did. I mixed the sodium bisulfite with 50cc of water before I started heating the fluid and had other measures already laid out in coffee filters. I will try the PC version next time. Will the results be like -P or -HD? I prefer the -P. My results indicated that the mid range didn't stretch out as much as -HD when doing N+. Plus the grain structure is different than -HD. I also highly recommend the rice cooker route.
    John
    John,

    The results with Pyrocat-PC should be the same as what you get with -P. The use of ascorbic acid or sodium metabisulfite gives almost identical working characteristics so in practice -P and -PC are highly alike.

    Compared with -HD the biggest difference I note, as you observe, is the grain structure. I find it just a tad larger, but somehow more tightly defined in away that enhances acutance.


    Sandy

  9. #9

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    Thanks Sandy,
    John



 

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