BVC - Low Extraction Rates OxladeMac at
Mon Nov 23 14:32:11 PST 1998

I can't figure out what I'm doing wrong.  I keep getting low extraction rates
from my mash every time I brew.  (By low, I mean sugnificantly lower than the
recepie calls for - like 1.040 rather than 1.052)  Let me review my practice,
and see if anyone can tell me what I'm doing wrong:

My mash tun is a modified picnic cooler.  I have built a false bottom out of
slotted copper piping, and the piping branches out to cover the entire bottom
of the cooler.  I have built a similiar manifold setup that I suspend to cover
the top of the grain bed for even and gentle distribution of water during

I grind my own grain.  I had the guy at the homebrew store show me the
consistancy that the grain should be ground to, and have set the gap on the
mill to give me similiar results.  It coincides with what Papazian recommends.

I use a single step infusion mash.  My strike water temp is 170 F.  I use
1.25-1.5 quarts of water per pound of grain.  I add all the water to the
cooler, then slowly stir in the grain.  The temp usually stabalizes at
152-154.  I let the mash go for 90 minutes.  Every 5 minutes or so, I open the
top and stir the thing up to make sure everything is well mixed, and all the
sugars get equal oportunity to get converted.  I do not do an iodine test at
end - I just go right into sparging.  I try to pace the sparge so it takes
about 45 minutes to do 5 gallons, 60 minutes to do 10 gallons (my mash tun is
larger for 10 gallons).    At the end of the 90 minute mash, the temp in the
cooler has typically fallen to about 146 due to all the opening and stiring.

I know I'm not getting all the sugars out of the grains, because many more
come out after the mash tun has been sitting for a couple hours (during
cleanup after the boil is done).  One thing I have done in the past is to
collect less sparge runoff for the boil, then continue the sparge an hour or
so later to get some more concentrated wort.  This works, but it takes a
longer boil because I typically have to boil some excess off.  One thing I
could do
is just add more malt to make up for the low yields, but that seems wasteful -
especially when I know there are more sugars in the grain.  Any ideas on how
to get a higher yield?
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