Rising OG

[Sloop]

Sorry if this is covered elsewhere, but I've just made a brew (my first without using a kit), and I've noticed that the OG is rising the longer I leave the hydrometer in the test jar. I was aiming for 1.050, it started at 1.048 and now, about half-an-hour later, it's 1.052. Anyone know why this is happening? Thanks.

[Kev888]

is the trial jar cooling? Cooler wort shrinks and becomes higher gravity (density) compared to warmer wort - thats why you need to correct for temperature. Hydrometers are calibrated to read true at a given temperature (either about 16c or 20c are the common possibilities), and you can get tables or calculators to adjust the reading if necessary to compensate for having used it at other temperatures.

EDIT: Don't plunge it into really hot wort though; the compensating gets less accurate as you get further from the design temperature, and you can also crack the hydrometer.

Cheers
Kevin

[Blackaddler]

Bubbles may also be clinging to the hydrometer. Give it a spin to release them.

[Sloop]

Well, some fast responses guys, thank you.

Yep, Kevin, the wort was indeed cooling when I took the first hydrometer reading. It's cool now and stable at 1.052. It hadn't occurred to me that the reading would change with temperature.

Blackaddler - I took your advice.

Thank you both very much. I'm raising a glass to you