Friction factor

Friction factor is how much Mixing heats the dough. It is a number in °F or °C that bakers plug into Desired dough temperature, not a physics coefficient. King Arthur Baking: mixer type, mix time, speed, and dough quantity all move it ¹. Change the protocol, throw the number away.

The water-temperature formula lives on the DDT page. Measuring friction keeps the calculation tied to the mixer in front of you.

Measure it #

King Arthur's precise method: choose a water temperature, record room, Wheat flour, water, and preferment if any, mix as you actually mix, then take dough temperature in the mass. Multiply that dough temperature by three (or four with a preferment) and subtract the known temperatures; the remainder is friction ¹.

Their illustrations describe their tests: a 7-quart KitchenAid on a stated stir-then-speed-2 protocol near 22–24 °F; hand mixing near 6–8 °F, or 0–4 °F for gentle folds and cool hands ¹. A bread machine that also heats the dough is a poor fit for this arithmetic.

Tweaking is allowed: if you aimed at 77 °F and landed at 75 °F, subtract 2 °F from the friction you assumed. A bakery log of water, mix, and outcome beats a formula used once ¹.

If calculated water is colder than ice or hotter than the tap, change the mix, the batch, or chill the flour. Do not invent a new equation. DDT itself is a fermentation starting condition for Fermentation scheduling, not a food-safety temperature.