Gravity readings

[stubrewworx]

When would a post mash reading be higher than post boil?

Post mash was adjusted to 1.052 (1.036 @ 65c), which is higher than expected and post boil (cooled) is 1.041.

I full volume biab, left in boiler overnight to cool, sure the hydrometer is good as I checked the 3 I have and chose this one. I only boil for 30mins, so wasn't expecting too much of sn increase?

Stu.

 

[Drunkula]

The details after the first question confuse what you're asking. If you could simplify things it might help.

Is there exactly the same amount of liquid post boil and post mash? Particles suspended in a mash gravity sample can give the illusion it's higher than it really is, too.

 

[stubrewworx]

Going into the boil i had 15.2l, end of boil 14.1l and ambient wort 13.6l.

I possibly took the sample with the bag still in

 

[dannythemanny]

Are you sure the correction for temperature is accurate? It doesn't seem possible that the gravity dropped from mash out to chilled wort unless more water was added at some stage. Could the first sample have been concentrated somehow? Pre-bag squishing, maybe? Still seems unlikely...

 

[foxy]

When would a post mash reading be higher than post boil?

Post mash was adjusted to 1.052 (1.036 @ 65c), which is higher than expected and post boil (cooled) is 1.041.

I full volume biab, left in boiler overnight to cool, sure the hydrometer is good as I checked the 3 I have and chose this one. I only boil for 30mins, so wasn't expecting too much of sn increase?

Stu.

Depends where you took your samples from, the density of wort will be higher at the bottom of the mash tun. It is impossible to get a higher reading post boil.

 

[stubrewworx]

Are you sure the correction for temperature is accurate? It doesn't seem possible that the gravity dropped from mash out to chilled wort unless more water was added at some stage. Could the first sample have been concentrated somehow? Pre-bag squishing, maybe? Still seems unlikely...

Yeah correction was correct and as it cooled, the reading slowly worked up to 1.052.

Yeah, I think I took the reading prior to removing and draining bag.

 

[stubrewworx]

Depends where you took your samples from, the density of wort will be higher at the bottom of the mash tun. It is impossible to get a higher reading post boil.

All makes sense now. I'll know for next time.

The projected 1.052 was higher than expected; which was very surprising, but the actual OG of 1.041 was much lower.

So I need to improve my mash efficiency.

Cheers,

 

[foxy]

All makes sense now. I'll know for next time.

The projected 1.052 was higher than expected; which was very surprising, but the actual OG of 1.041 was much lower.

So I need to improve my mash efficiency.

Cheers,

A lot of brewers seem to make a big deal from efficiency and turn it into a pissing contest. What you are looking for is consistency from your system and your method. Doesn't matter whether it is 50, 60, 70% efficiency it all come's back down to your system and method. As long as you are consistent and happy with what you are brewing that's all that matters.

 

[dannythemanny]

100% this. When I started AG brewing, I was so obsessed with getting my efficiency up to 80%, but looking back, I've no idea why! Grain is relatively inexpensive, especially to account for a 10-20% difference in efficiency. So now, I've decided it's better to be sure that I fill a 19L keg completely and have total consistency (and thus, replicability) in my system (because I could boil it down to 17L, and appear to have achieved better "efficiency") even if it's "only" operating at 69% efficiency. There's a great argument to be made for no-sparge having relatively poor efficiency with the trade off of not having to sparge, which can be a PITA and shaving an hour off of your brew day. I would probably choose to do most brews that way, but I can't usually fit all the grain and water into my countertop system.

 

[Scrattajack]

A lot of brewers seem to make a big deal from efficiency and turn it into a pissing contest. What you are looking for is consistency

Agreed, mostly. It was the conclusion I reached when my efficiency turned out to be quite low (~60%) and nearly all the articles on how to improve it said not to worry, just chuck a bit more grain in. This was fine for a while, system limit is about 6 kg which matched the sort of beers I wanted to brew. Trouble started when I fancied a mild, which used 2.8 kg of malt (rounded to 3 due to efficiency) for a 3.3% ABV ale. It ended up at 4.2%. Efficiency, it seems, varies depending on how much grain is in the tube. Certainly, when it has a full load it's a lot harder to stir in than with a half load.

So, consistent over similar recipes but not those with different grain bills.

 

[Drunkula]

Was listening to the Brulosophy Q+A #15 and somebody asked near enough the opening question. They said knock the warm hydrometer reading compensation on the head and get a refractometer, or you could chill the wort sample.

Somebody was having problems and it turned out their chiller was leaking water into the wort.