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Reshared post from +Wil Wheaton

#Homebrew question: I'm making a barley wine. My boil gravity should be 1.106. Hydrometer reads 1.042, and at 140* the adjusted SG comes out to more like 1.06. Iodine test says I have all the sugars out.

I mashed 22 pounds at 148 for 90 minutes, just like the book said. I have collected just about 6 gallons.

Did I sparge too fast? Do I put the wort back into the mash tun and keep it there for X minutes or something? Am I going to have to put LME or DME into the boil?

I will be very unhappy if I fucked this up beyond salvaging. Any help you can give me would be much appreciated.