Starter Sweet Spot

Been wondering for a while about yeast starters, specifically how far ahead of brew day I should be preparing, and how long to leave them on the stir plate. In the past I’ve gotten it wrong and ended up with a lifeless, limp soup which may or may not have taken off given more time, but resulted in me pitching dry yeast on top just to be sure.

Anyway. I’ve just kicked off Yeti XI and this time I feel the starter was close to perfect, maybe a couple of hours early. Here’s how it looked:

Jan 17 09:000hStarted, stir plate on, room temp 19℃. 
Jan 18 07:3023hStir plate switched off, central island of Krausen in evidence but still spinning.
Jan 18 10:0025hThick Krausen now, still some milkiness in wort.
Jan 18 17:0032hWort clearing, Krausen beginning to thin out but still strong in places.
Jan 18 21:0036hDefinite recession now, brew’s clearing up.
Jan 19 06:3046hKrausen separating, visibly past its best.
Jan 19 11:3051hThe end is nigh – pitching now.
1 packet M44, 99g DME, 0.8 litres water. 19℃ ambient temperature.

Looking at the images above I’d say that the sweet spot for preparing a starter for this brew is somewhere around 26 – 28 hours before pitching, with the first 23 hours spent on the stir plate. Obviously the type of yeast and fermentation temperature are going to play a role here, but going forward I’m going to aim for similar timing and will record the results.