Bottling my Christmas Ale today. My OG was 1.079 and FG was 1.014. That was with the shorter mash time of about 24 minutes. Pretty happy with that and will be doing shorter mash times from now on.
I did a traditional hour mash this AM because it worked out better with my morning activities. The result was an abortion. I measure brix when doing a stove top mash, and stir steadily and watch for conversion, which is visible as the mash thins and clears. With an hour mash, I simply wrap the kettle with insulation and blankets and forget about it. Mash temp was 152 at the start, and consisted of 5 pounds of two row and a pound of wheat malt, and a quarter pound of CR75.
When I unwrapped my mash and set it on the stove top the wort was still milky and thick, and the brix was only about 10....... far below my expected brix of 16. I started heating and stirring slowly, and at about 155, the brix took off and leveled out at 16. I'd only lost a degree and a half during the hour mash, so I'm not sure what went wrong. When doing hour mashes in the past, I never monitored conversion, I just trusted in God like everybody else, so I don't have a baseline for comparison. I presume the conversion probably completed previously as I heated toward mash out. (note that these brix readings are uncorrected refractometer readings.... I use brix during the mash instead of corrected SG..... I don't know why, I just started doing that and know what to expect).
Interestingly, my 20-30 minute mashes achieve the same attenuation as I was getting with a "conventional" 60 minute mash, so as far as I'm concerned, there is absolutely no reason to mash much longer than 30 minutes........if you do it right. "Doing it right" appears to be the challenge.
For me "doing it right" means doughing in at a fairly low temp and heating rapidly into the mid 140's, and then either managing my rate of temp rise, or doing a "splash down" with cold water from the low 150's back to the mid 140's and repeating the slow temp rise. Raising the temp faster, and straight through to the low 160's results in a lower attenuation wort. 155F seems to be the magical temp where conversion happens very rapidly, but fermentability is reduced if you get there too fast.
I'm reaching the point where I can predict attenuation pretty accurately. I design my mash procedure and know at the outset where I'm going to end up fairly closely. I'm for some reason not achieving the efficiencies I was......... this one hit 79% according to Brewer's Friend, but that's pretty darn respectable.
H.W.