Mash thickness

[Leo1983]

I havent brewed for a while but if i remember rightly, most recipes recommend a mash of like 1-1.5 litres of water per pound of grain.

I tried doing this for a bit and found this to get my 50l mash tun about 2/3 full when brewing a fairly strong recipe.

I think this gap in the tun affects the temperature retention though as i have noticed a fair few degrees being lost after the hour.

This may be why my stout that was supposed to be like 8 percent came out at 5.5 with a much higher finishing gravity than it was supposed to (although should a lower mash temp make it more fermentable?).

next time i may just fill the tun to the top to keep temp better, any problem with doing a thin mash like that? I think consistent temp will be more important as i have heard mash thickness shouldnt make too much difference when only brewing around 20 litres. Any thoughts?

 

[cushyno]

I recall that German brewers typically use a thinner mash. Your figure of 1.5 l per pound roughly equates to my metric brewing equivalent of roughly 2.7 l/ kg. The anecdotal figure for German brewers if I recall correctly is 5l / kg, so you have plenty to play with. Thinking that many brewers do a full volume mash and the figure goes even higher.

It's not so much the empty space in your mash tun as the small volume to surface area that results in heat loss. Depending on the shape of your mash tun, if it's broad and low doubling the volume doesn't come anywhere near to doubling the surface area where heat can be lost, so greater volumes are much better at retaining heat relative to small volumes.