I've given this failure a lot of thought (okay, I admit it...I've been obsessed with it) and I honestly can't say for sure what process I followed.
This was a bad batch from the start, mainly because I was working in a brain dead state.
I do know that I screwed up the amount of proprionic I added at first. My 5 gallon recipe called for 2-1/2 tsp. and I only added 1/2 tsp. and then had to add more, after the milk had already started to acidify.
I also do think that I added the calcium chloride at the same time I added the starter but I can't be certain.
That being said, I've added calcium chloride before the milk has been warmed.....right before renneting.....at the same time as the starter and even a couple of seconds after renneting if I realize I have forgotten it. Even with all of this variation, I've never failed to get a good set.
I really don't know what I did wrong here but the rennet I used is from the exact same batch I used two weeks ago with no problems. I screwed up somewhere, but I'm just not sure where.
As I said, I was pretty much brain dead when I started this batch.
First of all, I set my milk by one of the heat vents to help it warm and forgot about it for 4 hours. By the time I poured it into the vat it was at 80 degrees which I don't think should have caused a problem, but who knows.
Also, I checked the empty jugs and the expiration date on the milk was 3-7-09 which was only 6 days from when I tried making this batch. Usually my milk is still close to two weeks from the expiration date.
It could have been any of the aforementioned things or it could have been a combination of all of them.
Regardless, I'm not going to try making cheese while sleep deprived, mentally stressed, emotionally drained and a bit hung-over, again. I've learned my lesson.