[gymrat]

Is it true a thick mash produces a fuller bodied beer? If so what would be considered a thick mash?

[denny]

I have not found that to be true. 

[Thirsty_Monk]

I agree with Denny.
Thinner mash is easier work with and has more thermal mass.
1.4 to 2.0 is a good ratio.

[Mark G]

Theoretically, I believe it's true. Practically, however, I can't detect any difference whatsoever. Mash temperature has a much, much bigger influence on body.

[denny]

I should modify my answer to say that I haven't detected any difference in the finished beer from using a mash thickness from .75-2 qt./lb. 

[euge]

Hasn't made a difference to me as to body, but it might affect your conversion, as in slowing it down. If I have a thick mash then I mash longer. Others don't though. YMMV

[mabrungard]

I used to mash in the 1.25 to 1.33 qt/lb range with my RIMS.  I thinned my mashes to about 1.5 to 1.75 qts/lb in the past couple of years and have not noted a difference in body or fermentability due to that factor.  Mash temperature is more influential to fermentability in my opinion.  Body can be somewhat influenced by wort fermentability. 

The other big factor in body building is the level of beta-glucans in the wort.  That is a super body builder, but has to be managed carefully to avoid clouding the beer. 

Now I feel that mash thickness should be viewed as a factor decided by the size of the brewer's mash tun and the water chemistry of the water.  The water chemistry plays its part through the amount of alkalinity that the water delivers into the mash.  If the mash pH is a little too high because the water alkalinity is too high, then reducing the amount of water in the mash (thickening the mash) might help produce a decent mash pH.  If the water has low alkalinity and the mash demands more alkalinity, then adding more water (thinning the mash) may help produce a better mash pH.

In general, I think that mash thickness in the 1.5 to 2 qt/lb range is a good starting point.  I don't see a reason to aim for thicker mashes unless you can't fit it in your tun.

[euge]

Thanks Martin that actually helped me a bit. My mash is usually 1.6 to 2 qts. I've had trouble converting really thick mashes like 1.15 qts.

[gymrat]

Thankyou for your replies.

[paul]

I've actually heard the reverse: a thick mash produces a more fermentable wort.  The explanation is that in a thick mash the enzymes are less diluted and more available to do their work on starches.  And since beta amylase is responsible for producing very fermentable worts, and it denatures faster than alpha amylase, it makes sense that anything that allows the enzymes to work faster will give beta a chance to work while it can.  I've gotten some pretty good attenuation with mashes in the 1.1 to 1.2 qt/lb range, but I can't say I've done any experiments.

[veldy]

Is it true a thick mash produces a fuller bodied beer? If so what would be considered a thick mash?

If it produces more body in the beer I suspect this might be caused by hot spots and perhaps dough balls in the mash.  I personally haven't experienced this and usually mash around 1.25 to 1.33 qt/lb regardless of style.

Veldy

[nateo]

The rules-of-thumb about mash thickness were made up back when malt was enzymatically weak. I read that in thinner mashes, the alpha amylase is denatured more quickly than in a thicker mash. This is why old texts recommended to mash thick and hot for a full-bodied beer.

Most modern malts have so much excess enzymatic power (100-120+ DP), it doesn't matter if some, or even half of the enzymes are denatured in a thin mash. There will still be plenty left to fully convert.

I mash super thin now (4-5L/kg, which is about 2-2.4qt/lb), and haven't noticed any difference in the fermentability or body of my beers.