Preboil gravity will go up over time?

I noticed this last night and tonight (doing second AG WOO!!!). After I collect all my wonderful, delicious, aromatic wort, the preboil gravity seems to be a little low. After it sits for half an hour to 45 minutes (before I start the boil) it goes up? Last night it went up almost 14 points. Its been sitting for 15 minutes tonight and has gone up 5 points already???? Why does it do this? Is it lying to me?

Are you adjusting for temperature?

I'm confused (easily)
Why is your wort sitting for 45 minutes before boiling?

It sounds like temperature to me!

No, I'm not adjusting for temperature... I have no idea about that, never heard of it. I'll look that up. Anyone got a quick explanation of how temperature effects it?

It's sitting because I can only do half at a time, I guess half of its actually sitting for more like an hour, not 45 minutes. I just noticed it was doing it at 45 minutes of sitting last night.

Sure. It's very important.

The density of a liquid varies with temperature and pressure. Your pressure is constant but the temperature is not.

Most US hydrometers are set to read correctly at 60°F UK at 20°C any other temperature will give an inaccurate reading.


Here's a guide I've been working on.

https://www.homebrewtalk.com/wiki/index.php/Hydrometer

Always take the temperature of the liquid being tested.
The following corrections are for a Hydrometer rated at 20°C / 68°F
10°C (50°F) -0.002
15°C (59°F) -0.001
20°C (68°F) -None
24°C (75°F) +0.001
28°C (82°F) +0.002
32°C (90°F) +0.003

The following corrections are for a Hydrometer rated at 15°C / 60°F
10°C (50°F) -0.005
15°C (60°F) -None
21°C (70°F) +0.001
25°C (77°F) +0.002
29°C (84°F +0.003
35°C (95°F +0.005

Click to expand...

THanks Orfy, sorry for the dumb question, I went straight to google after posting, should've gone before. Makes sense, I found some good correction charts.

Well it's better to ask a dumb question and learn than not ask and not learn.
Although the EAC in me says it's much better to learn and not ask a dumb question.


No problems, glad to help.


Mystery solved hey.