Sparging and squeezing questions

[forgetaboudit]

Hey all,

Im 4 brews deep into my BIAB life. A few questions popped into my head after struggling with boil volume and low OG (getting better with each brew).

I use beer smith and was wondering how to input something to account for the extra volume after squeezing the grain bag? I feel this is where my boil-off/volume issues are originating from.

Ive been told to try dunk sparging to be sure I get all the sugars from the grain. Ive dunk sparged in two stages with 2 different kettles with room temperature water. Would mash temp water be better? I was thinking of trying it next brew session.

 

[RM-MN]

Water temp has little to do with getting out the sugars. The usual problem with low OG is not getting a fine enough crush.

 

[Oginme]

Hey all,

I use beer smith and was wondering how to input something to account for the extra volume after squeezing the grain bag? I feel this is where my boil-off/volume issues are originating from.

If you know the mash water in vs mash water out, then you can recalculate the grain absorption rate. You can update this in BeerSmith under 'options' > 'advanced' > 'grain absorption' or 'BIAB grain absorption'. Note that the BIAB grain absorption figure only works with mash profiles which are checked as being 'BIAB mash with full volume', otherwise the program uses the standard grain absorption figure. If you want to include a sparge step in your BIAB process, then you need to treat your system as a standard mash tun process within the software.

 

[MikeCo]

I strongly agree with Oginme on calculating grain absorption by monitoring your pre and post mash volumes. I found the default BIAB absorption value in BeerSmith to be high, since I squeeze the bag. I currently have that value set as 0.465 fl oz/oz. For your next few brews, make a spreadsheet using grain weight and pre/post mash volumes and calculate grain absorption per pound and convert it to fl oz/oz. Take an average and adjust the value in BeerSmith.

And yes, you need to make sure you check the "BIAB mash" box in the mash profile you use.

Also - check the boil-off rate in your equipment profile for accuracy. Like the grain absorption, record pre and post boil volumes for your batches and adjust the value as needed.

I never bother with dunk sparging (or any sparging). I mill my grains finely (mill gap is 0.030 inch) and squeeze.

 

[David SEMich]

How do you get meaningful measurements of volume? Wouldn't you want to get within 4 ounces or so? I think I wouldn't get that close with my kettle markings.

 

[balrog]

volume measurements will be the trickiest thing, at least it was for me, and I just did

THE

SAME

PROCESS

EVERY

TIME

and kept track of it. Eventually, for that process, the volumes worked out. But the work is in doing it exactly the same. Draining is all I do with my BIAB. No squeeze, no sparge, always the same draining time. Repeatability, aye, that be my mantra. And use sunscreen. And don't drop your reading glasses into the boil.

 

[Oginme]

How do you get meaningful measurements of volume? Wouldn't you want to get within 4 ounces or so? I think I wouldn't get that close with my kettle markings.

I made a measuring stick from a piece of 1 inch aluminum stock. I use a slurry of corn starch and food coloring to coat the aluminum stock and allow it to dry. This gives my easy marking of the levels as I do the next steps.

I filled a cooler full of water at a temperature of 60F and then weighed water by the liter (1 liter at 60F = 999 grams) into the kettle I am looking to calibrate. Once this has settled, I put the aluminum stock piece in and the colored corn starch will dissolve off the stick at the level of the liquid inside. I then measure this and add another liter: dip, measure, repeat.

I can then take a permanent marker and mark the aluminum stock with lines for each liter, and using the mid point for half-liter markings. For smaller pots, I can also put in quarter liter markings without crowding. I use an etching pen to make these marking permanent. I estimate my error of measurement to be around +/- 50 ml, but my actual calculations of the gravity point balance has me at less than 10 to 20 ml variability.

BTW, I have several kettles with permanent markings. Of all of them, only one was dead nuts accurate in the markings. The rest were off by varying amounts which is to be expected from standard variability of mass production.

 

[forgetaboudit]

I'll try to monitor the volumes and calculate my absorption. Now I need to fine tune my volume markings on my keggle.