I made a Caerphilly yesterday, and I had a bit of a shock.  I’ve been using the flocculation method to check for curd set time.  I start checking at about 10 minutes, and then every minute thereafter until the flocculation point is reached.  I have never had one at less than 13 minutes, and have had it go as long as 19 minutes on one occasion.  So yesterday, when I put the bowl in to check at 10 minutes, I was shocked to see that it had already passed the flocculation point.  This left me with no clue as to when the curd would be ready, except to test frequently for clean break.  Well, at 20 minutes, the curd was ready to cut.  I don’t recall ever reaching clean break before 35 minutes in the past.

I’m not sure what difference was in play to cause this quick set; but the lesson seems to be keep on your toes.

Same rennet as always? Sure about the qty of rennet? Other milk? Raw milk (Is giving me different floc times depending on the cow where the milk is coming from)?

Rennet from the same bottle as the last 15 batches, measured to be the same quantity - 1/2 tsp.  I’m using raw milk from the same source - in fact from the same cow, since the woman I buy from only has one.

Temp the same ?
Rennet will change with age also.

Yes, temps were the same.  Seems odd that rennet would get stronger with age, rather than weaker.  In any case, the two I’ve made since this one have been back in the normal time range.  Chalk it up to a freaky oddity I guess.