Missing Wort

[UsernameTaken]

Sorry, I posted that as your reply appeared!

This never used to happen and now it always happens!

I'm not sure if it's just cause i'm measuring things more precisely now?

Or less precisely as it may be!!

 

[S.E]

Are you allowing for shrinkage (well, you know what I mean) of the liquid as it cools from boiling?

I’ve already asked that post #2 but didn’t get an answer.

 

[UsernameTaken]

I said in post in #15 "I was not aware of shrinkage! Is this a thing?"

 

[Brewno Marz]

The volume of a set amount of a liquid varies with temperature.

Edit: maths deleted, as I assumed the temps. What temps were the readings taken? I can then re-do at actual temps

 

[UsernameTaken]

Wow, good maths and science Brewno, I will happily take your word for it and stop worrying!

Cheers,
UNT

 

[MHB]

When you take a gravity reading if you want it to be accurate you need to correct for temperature, above 4oC water expands as it gets hotter, so becomes less dense (1kg takes up more than 1L) so your hydrometer sinks lower
At 100oC a water has a density of 0.9577 around 0.042 less than water at 4oC (maximum density).
From that we can calculate that 1L or 1kg at 4oC (SG 1.000) would have gained volume to about 1.044L
So yes shrinkage is a real thing, the standard number (rule of thumb) is 4% between boiling and pitching temperatures (it would be 4.4% at 4oC but a bit less at around 20oC)
Mark