Larousse, sorry for the messups, this is the first time posting. Yogurt has to be made after having heated milk to about 195 degrees. Hold it there (I use a double boiler so as not to burn the milk) for about ten minutes. Then, transfer the scalded milk to an ice bath. Using a double boiler makes this easy: just lift the DB containing the milk up and put it into a larger pot prefilled with iced water. It will cool pretty rapidly. When at about 100 degrees (all Ferenheit), plop in (innoculate) 1 or 2 Tblspoons to one quart of milk, active cultured yogurt and whisk. When it is incorporated, the temp should be about 95.0 F. That's when you fill the yogurt cups and incubate. This is not an exact science for me. I made many attempts. If I added the cultured yougurt too soon, the final product was stringy (no issue except aesthetic). If I scalded the milk too long, it got too firm and tart. You have to play with it. Good luck. John S. San Jose, CA