How much of a difference does mash thickness make?

[DrewG]

I normally mash with 1.5 quarts per pound of grain. I calculate my strike water temp using the equation in Palmers book for a preheated tun:

tw= (.2/water to grist ratio) (target mash temp - grain temp) + target mash temp.

I batch sparge, and from what I understand I will have my best efficiency if my first and second runnings are an equal volume. Depending on the total grain in my recipe, which changes all the time, I get different runoffs every batch. For instance, I'm brewing today and my total grain bill is 11 pounds, adding in my dead space and grain absorption my strike water will be 6.5 gallons, giving me a 1st runnings volume of 4.5 gallons, then I'd sparge with 3 gallons to get my 7.5 desired preboil volume.

My question is this:
Can I just adjust (reduce in this case) my grist/water ratio to make my  first runnings 3.75 gallons? How will different ratios effect my beer? My ultimate goal is to get consistent efficiency batch to batch, will my extraction be all over the place if I change up the grist/water all the time?

[roguejim]

I do exactly what you are suggesting you want to do.  I try and keep my first runnings, and sparge within a 1/2 gal of each other with no concern for the grist:water ratio.  If my memory is correct, I don't recall Gordon Strong being too concerned with this ratio either.  I've also found that a thinner mash makes it easier for me to hit my strike temps dead on.  I batch sparge.

[euge]

My ultimate goal is to get consistent efficiency batch to batch, will my extraction be all over the place if I change up the grist/water all the time?

Yes.

Mash thickness and grain-bed depth both have impact on your efficiency. One aspect of it is that if you use less water you will rinse less sugar out.

The best way to get consistency is not change your variables too much. I wouldn't expect to get the same eff with an 11# grist vs a 21#. And the same goes with the water. Reduce your overall water and eff will suffer. I try to use the same bill, same ratio and amount of water to gain consistency. Then you can extrapolate what will happen if you increase/reduce the amounts.

[hubie]

The short answer, I believe, is for the level changes you're talking about (which if I did the math correct is changing from 1.5 qts/lb to 1.2 qts/lb) is that you wouldn't notice much difference and you shouldn't worry about it.

Kai Troester did some nice experiments on mash thicknesses http://braukaiser.com/download/Effects_of_mash_parameters_on_attenuation_and_efficiency.pdf.  His results, and the results of others he cites, suggest that mash thickness has little effect on attenuation.  He did see a temperature effect of mash thickness on overall efficiency.  He was comparing mashes done at 1.2 qts/lb and 2.4 qts/lb and found that the thin mash had better efficiency at higher temperatures.  I suspect that for the amounts you want to change and the temperatures you'll most likely be at, batch-to-batch variations in your efficiencies will depend more on your measurement accuracy than changes in your mash thickness.

[mabrungard]

Depending on the water chemistry and grist composition, mash thickness can substantially alter the mash pH. That might have more to do with the differences in efficiency and attenuation than the thickness or thinness.

[DrewG]

Thanks Martin. Water is my next hill to climb.

[DrewG]

I try to use the same bill, same ratio and amount of water to gain consistency. Then you can extrapolate what will happen if you increase/reduce the amounts.

This sounds like a good approach. The problem is brewing the same grain bill more than once 

[denny]

I try to use the same bill, same ratio and amount of water to gain consistency. Then you can extrapolate what will happen if you increase/reduce the amounts.

This sounds like a good approach. The problem is brewing the same grain bill more than once 

IMO, that's one of the keys to learning to be a great brewer.

[DrewG]

IMO, that's one of the keys to learning to be a great brewer.

I need to find one beer I really like, then. This could work out great for my friends

[euge]

IMO, that's one of the keys to learning to be a great brewer.

I need to find one beer I really like, then. This could work out great for my friends

You can vary the hops and yeast up and have a different beer quite easily without altering anything else.

[DrewG]

You can vary the hops and yeast up and have a different beer quite easily without altering anything else.

Good point. Session IPA maybe?

[thebigbaker]

You can vary the hops and yeast up and have a different beer quite easily without altering anything else.

Good point. Session IPA maybe?

I think I just heard Denny scream!

[denny]

AAAAAAAAAARRRRRRRRRGGGGGGHHHHHHHHHH!


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[ccfoo242]

AAAAAAAAAARRRRRRRRRGGGGGGHHHHHHHHHH!


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Introducing, the Denny Conn AAAAAAAAAARRRRRRRRRGGGGGGHHHHHHHHHH! Session IPA!

[wamille]

Session IPA = Pale Ale?