Well just had my first encounter with the slimy yogurt that I've heard so much about reading the archives. I thought I'd post the procedure I followed and perhaps the experts can zero in on the causes and techniques to avoid it.
I deviated from my normal yogurt making procedure and here's what I did.
1. I poured 6 quarts of store bought Organic Pasteurized and Homogenized milk (Horizon) into my new
Cheese Vat. 
3 Quarts were 2%, and the other 3 Non fat. I use this milk a lot and in my standard yogurt making procedure it has never produced slimy yogurt before.
2. Via the double boiler I then brought the milk up to 185F and held it there for 30 minutes. The vat was uncovered as it is too big for any sort of a lid. I usually warm up the milk very slowly. Maybe over the course of 3 hours to arrive to 185F. But yesterday I did it within an hour.
3. I let the milk cool to 115F and added 2 cups of yogurt, a little more than usual. Normally I use the Strauss/Trader Joe's European style Organic yogurt. Either store bought or from my previous make and the results have always been consistent. This time it happened to be from a previous make.
4. I left the inoculated milk to incubate for 8 hours and the yogurt did not set. Over the course of the day I had to heat up the double boiler a few times to maintain the 115F temperature. I waited another hour and the yogurt still did not set. I bundled it up as best as I could, covering it with my baking sheet on top and some kitchen towels
and went to bed as it was already 10pm. Yes I'm getting old.
5. By 7am this morning the yogurt set, but it looked somewhat slimy. I recognized the look since I saw it described here multiple times. So my mind started racing to figure out what happened. I then proceeded to ladle the yogurt into the quart containers and realized that I only have 4 Quarts of yogurt.
So basically I lost 2 quarts worth of liquid during the making process. Also I had absolutely no whey. In my normal process I always have some whey in my yogurt.
My intuition tells me that the excessive moisture evaporation may be a big reason why I got the slimy yogurt. My second suspicion is on the maintaining of 185F for 30 minutes. But I will wait for the gurus to chime in and break this down so we can finally pin down this slimy yogurt phenomenon.
As a side note the flavor of this make was very very mild, as opposed to my usual extra tangy European style flavor. However, I suspect this has nothing to do with the slimy texture. The mild flavor is probably due to temperature falling too low overnight and no longer being anywhere near 115F.
So what do you guys and gals think?
