70 replies to this topic

[djinkc]

How do you know what your gravity should be if you don't know the efficiency of the system? Is it just a calculation based on theoretical values? Serious questions, no snark at all...

I'm guessing you know when gravity stops changing. Nice time to have a refractometer I guess.

[Genesee Ted]

Yo tengo una refractometer. So the takeaway lesson is that the iodine test is snake oil of sorts?

[Brauer]

How do you know what your gravity should be if you don't know the efficiency of the system? Is it just a calculation based on theoretical values? Serious questions, no snark at all...

Kai Troester's site on Understanding Mash Efficiency has a lot of great information.Particularly useful here is the conversion efficiency chart. Basically, it tells you what the gravity should be at a given mash thickness at 100% conversion. Look up your mash thickness and it will tell you what gravity you would see at complete conversion. It doesn't matter what your final mash efficiency is, complete conversion is the same value for a given grist. And, yeah, a refractometer is very helpful.

[Genesee Ted]

Thanks for the links!

[Brauer]

You can figure out the target gravity for your specific mash with a little math, but it is slightly complicated by the fact that the sugar increases the total volume as it goes into solution.If you always mash at the same thickness, it's easy to just learn the target gravity for that thickness. For example, if you mash at 1.75 qt/#, the mash will be fully converted when it hits ~1.071. 2 qt/# is more typical for me, so I look for a gravity of ~1.064. Realistically, I look for at least 90-95% conversion, so I'd consider a 2 qt/# mash done as soon as the mash gravity gets near 1.060.For those of you that mash thick, 1.5 qt/# would be fully converted just over 1.080.

[Clintama]

I don't think the ratio of mash water versus sparge water is that critical, but the the temperature of the sprage water needs to be as high as possible without leaching tannins.

[denny]

I don't think the ratio of mash water versus sparge water is that critical, but the the temperature of the sprage water needs to be as high as possible without leaching tannins.

Actually, tannin extraction is pretty much dependent on pH, not temp. Otherwise decoctions wouldn't be possible.

[Clintama]

I keep my mash under 170 F at all times, so it's not a problem for me.

[denny]

I keep my mash under 170 F at all times, so it's not a problem for me.

Nor would it be if you went over 170 as long as your pH is good.

[Clintama]

Not so sure about that, but I'm not willing to risk it anyway.

[djinkc]

Nor would it be if you went over 170 as long as your pH is good.

I've gotten tannins sparging under 170df and good pH - simple oversparging a very low gravity beer. Next time I'll just dilute to the gravity I want after sparging

[denny]

I've gotten tannins sparging under 170df and good pH - simple oversparging a very low gravity beer. Next time I'll just dilute to the gravity I want after sparging

But wouldn't oversparging raise the pH so that it was ultimately the culprit?

[MtnBrewer]

But wouldn't oversparging raise the pH so that it was ultimately the culprit?

Yes, particularly if it was a low gravity beer to begin with.

[djinkc]

But wouldn't oversparging raise the pH so that it was ultimately the culprit?

Yes, particularly if it was a low gravity beer to begin with.

It's been a while but I suppose it's possible since I was fly sparging. I'll need to check my notes but I remember being concerned about this and checked runnings with chlorphast strips several times. At the time I wasn't concerned but the beer did end up with a bit of tannic astringency.

[denny]

It's been a while but I suppose it's possible since I was fly sparging. I'll need to check my notes but I remember being concerned about this and checked runnings with chlorphast strips several times. At the time I wasn't concerned but the beer did end up with a bit of tannic astringency.

Were you applying the correction factor for ColorpHast strips?

[djinkc]

Were you applying the correction factor for ColorpHast strips?

IIRC you want about 5.2 with those strips to be in the good range, right? Every wort reading I've taken here has been in the low 5's. The strips were a few years old then.

[Genesee Ted]

I don't think the ratio of mash water versus sparge water is that critical, but the the temperature of the sprage water needs to be as high as possible without leaching tannins.

I suppose, but this is kind of not what I am talking about

You can figure out the target gravity for your specific mash with a little math, but it is slightly complicated by the fact that the sugar increases the total volume as it goes into solution.If you always mash at the same thickness, it's easy to just learn the target gravity for that thickness. For example, if you mash at 1.75 qt/#, the mash will be fully converted when it hits ~1.071. 2 qt/# is more typical for me, so I look for a gravity of ~1.064. Realistically, I look for at least 90-95% conversion, so I'd consider a 2 qt/# mash done as soon as the mash gravity gets near 1.060.For those of you that mash thick, 1.5 qt/# would be fully converted just over 1.080.

1.5 qt/lb is thick? Damn! I always mash at 1.25 and sometimes even lower if I really need the tun space. I don't think I have ever mashed over 1.5

[denny]

IIRC you want about 5.2 with those strips to be in the good range, right? Every wort reading I've taken here has been in the low 5's. The strips were a few years old then.

Yeah, I think so assuming you were at room temp. From Martin....SPECIAL NOTE: Plastic pH strips (ColorpHast-trade name) typically used by brewers are reported to miss-report mash pH by about 0.2 to 0.3 units lower than actual. Brewers should use caution when using pH strips to measure mash pH. Without another means of pH verification, brewers are advised to accept a pH strip reading that is about 0.2 units below their targeted mash pH to avoid overshooting the pH. A pH strip reading of about 5.0 to 5.2 should indicate an appropriate room-temperature mash pH of around 5.3 to 5.5. pH measurement by a calibrated pH meter is recommended. Common paper pH strips are not recommended for brewery use since they are reported to have less reliability and accuracy than plastic pH strips.

[denny]

I suppose, but this is kind of not what I am talking about 1.5 qt/lb is thick? Damn! I always mash at 1.25 and sometimes even lower if I really need the tun space. I don't think I have ever mashed over 1.5

I've gone to 1.65 or more. Great results...it actually raised my efficiency just a bit.

[Genesee Ted]

I could totally see that raising efficiency. The problem that I (and I assume brewers for millenia) have often encountered is an undersized mash tun :blush:I am in the process of setting up a 20 gal B3 pilot system at work. We will probably only do 15 ish gal batches in it most of the time, so I am definitely looking forward to the luxury of an over sized mash tun!