Kettle Sour Steps
Starter
-Create a starter with 200 g DME, 2L of filtered tap water, and a pinch of yeast nutrient.
-Add 1/2 tsp 88% lactic acid (should get pH down < 4.5).
-Chill to ~110ºF, add 2 cups uncrushed rye malt.
-Top the starter off with carbonated water. This will purge oxygen and reduce headspace.
-Cap flask with airlock. This will ensure the aerobic competitors do not get the oxygen they need to produce off-flavors.
-Keep the starter as warm as you can (~110ºF is best) for 2-3 days. Strain then pitch directly into wort.
Mash
-Mash in, collect wort, and reduce pH to 4.0-4.3.
-Boil for 15 min (no hops!).
-Cool to 100F and pitch starter.
-Purge headspace with CO2, cover w/ Press'n Seal plastic wrap.
-Hold as close to 90-100F for 24-48 hours.
-Check pH in 24 hours, hold for additional time (if necessary) until pH is 3.2-3.6
-Once desired pH is reached, complete boil and continue as normal.