BIAB mash temperatures

After a recent tragic brew-in-a-bag that stopped fermenting at 1.036 and resolutely refused to go any lower, my autopsy concluded that most likely my mash temperature was too high.

But what should my mash temperature have been and what variables are at play? My findings in summary…

• Low temperature – 148 to 152 F – 64.4 to 66.6 C – needs a longer mash – more complete conversion of starches to sugars = cleaner, lighter tasting beer.
• Medium temperature – 153 to 156 F – 67.2 to 68.8 C – medium bodied beer.
• High temperature – 157 to 158 F – 69.4 to 70 C – less starch conversion, more unfermentable dextrines = fuller bodied, fuller flavoured beer.
• Higher – 158 F – 70 C + … ?