Safety issues with heating glycol.

[gainer]

It has been pointed out to me that heating anything in a microwave oven can be dangerous. I have not had any fires or explosions, but I have seen that at high temperatures, a solution of ascorbic or isoascorbic acid in glycol will have a color. Further experimentation indicated that this color might be due to decomposition of the acid. Products of such decomposition include furfural and L-xylosone. The latter appears harmless. The furfural is something I don't want in my developer, even if it does superadd to phenidone. I'm not sure that's what I got, but just the fact that it could be goes against the premise, if not promise, that there is nothing harmful in my ascorbic acid developer. Besides, I did an experiment using a Pyrex pitcher in a water bath in an open, electrically heated tea pot so I could observe the temperature at which all of the ascorbic acid needed to make a 10% solution would dissolve in glycol. It was all dissolved by the time the temperature in the glycol reached 150F, and the solution stayed water white. Adding 0.2 grams of phenidone did not change the color. Thus it is possible to dissolve the ascorbic or isoascorbic acid without reaching the decomposition temperature of the acid. Since it is difficult to control the temperature in the microwave, I will have to recommend that it not be used, for the purpose of avoiding the decomposition if not for safety's sake.

 

[Ole]

I would suggest that anyone mixing their own chemicals on a regular basis take "the lazy way out" and get a magnetic stirrer with heating. Heating liquids in a microwave oven is at best uncontrollable, and at worst downright dangerous.

With a stirrer you can even dispense with the usual advice about dissolving Metol before the sulfite!