Conversion time at 150 degrees?
 

How long should I mash at 150 degrees to get full conversion? 60 minutes? 90 minutes?

Yes. :) Seriously, 60 should be plenty but grist bill and mash thickness will have an effect on it.

just check for conversion with the iodine test, I think 75 would be plenty enough time though.

I find the iodine test pretty much worthless since you can get false readings so easily.

ok, just wait longer then ;)

seriously though, I have never had conversion problems with a 60M mash, I think it is just a matter and set it and forget it.

I'd agree with with ya, given most malts and a 150 mash temp.

If you're not checking for conversion, you really don't know if it converted, no matter how long you mash. I don't quite get what is meant above by "false readings". If you still have starch, you will get a positive reaction when you do an iodine test. Anytime I've gotten a positive reaction for starch, I knew I had to wait longer.

If you want to know more - read up in this thread:
http://www.homebrewtalk.com/f36/ah-yes-im-not-getting-conversion-i-think-150464/#post1721818

Thanks for the info.

OK...possible stupid question. If you are mashing dark grains for a stout how do you know if you converted starch to sugar with iodine? Doesn't iodine turn the liquid black if there is still starch?

Conversion can happen in as little as 15min. Test it.