[dzlater]

 I am planning on sour mashing 2.5 lbs of grain.
I understand that you want to minimize contact with oxygen during the process.
My idea is to put the mash in a ZipLoc bag and get all the air out and seal it up.
Put the bag in a larger pot of 120º f water with a thermometer in the pot, stick the whole thing in the
oven and try my best to keep it between100º and 120º for 24 hours. Or maybe a cooler instead of the pot / oven ?
Anyone see any major flaws in this plan of action?

[hoser]

Skip the ziploc bag.  Just put the sour mash in the crockpot.  I may be mistaken, but you may need to do your saccrafication rest first to convert the sugars and then mash out above 170F?  Once that is converted, cover the mash with saran wrap.  That will be sufficient to keep out the oxygen.  Then set the crock pot to  the lowest setting to keep it around 100-100F.  This will be the best and safest way to maintain your temps.  Once that is soured to your liking (48-72hrs), place that back in your main mash and proceed as normal.

[dzlater]

I was considering the crock pot but read that they heat up to 170ºf, which would be too hot.
I just thought the ziploc would be a god way to keep out air?

[tschmidlin]

My crock pot gets too hot on low.  I've never measured the temp, but it bubbles gently around the edges.

[tomsawyer]

I don't see the real need to prevent all contact with air, I haven't had hat much acetic character develop in my few attempts.  I just leave the mash in my cooler mashtun for 24-36 hours with the lid on.  It converts and then as the temp drops the bugs get going.  Gets real funky smelling, but it creates a modest lactic tartness.  if you do a mini-mash I'd definitely let it go a good long time otherwise when you add it to the rest of the wort it won't have much of an effect.

[b-hoppy]

All my efforts have been successful without any problems due to oxygen.  Just mash your grain like you would for a regular beer then cool it down to about 100F.  Put some plastic wrap over the surface and let it set.  My oven light keeps the temp inside the oven right at about 100F.  Within two days it's like 'funky' lemonade.