With Herself at Work, and The Bairn at nursery, I was able to give my Tetenal C41 kit its first outing. I'd lost the instructions, but got the basics here , and a whole lot more here . I used a plastic bowl in the kitchen sink, and warmed the chemicals there first, (I made up 500ml of each - developer, blix and stabilizer, and put the first in an elderflower cordial bottle, the second in a tomato sauce bottle, the third in a brown sauce bottle). I used an electronic thermometer, the sort you use to see if you have a temperature, so it was very accurate. It was 39.5C when I started. The developing is the most temperature crucial part, but it's only 3m 15s, so it wouldn't have dropped by more than a degree or two, I'd guess. The counter-intuitive part comes when you add the blix straight after the developer, but then, heigh ho. Then the rinse, then the stabilizer, and then... no final rinse. The stabilizer is a bit sticky, so it seem...