Measure Specific Gravity with a Hydrometer

http://www.forrestwhitesides.com/node/49

Props to Forrest Whitesides, I heard this on Final Gravity Podcasts yesterday!

 

Good quick thinking, but there are several problems. Gravity is affected by the amount of sugar in solution, and you can reasonably measure that using a scale. I'd want to use a lot more than 40g to get a precise reading, but the principle stands.

The problem is that wort has all manner of undissolved, itsybitsy solids floating around that don't affect gravity but will affect weight. Eventually these would settle out due to differences in density, but that takes time and I don't suspect he waited for it.

Also, this line made the ghost of my high school science teacher cry:

Edit: also, this thread would probably draw more interest if you titled it "Measure Specific Gravity withOUT a Hydrometer"

 

Disconnect between the keyboard and my Brain Housing Group there, sorry!

 

So he spent 35$ to avoid spending 8$ on a hydrometer?

Also: since he measured the weight of a liquid and compared it to water, he didn't *avoid* a hydrometer, he basically built a hydrometer that happened to cost much more and also be much less precises.

 

He used what he had on hand to come up with a creative solution to a problem. He already had the scale and a way to measure liquid. It's just a quick and dirty way to get an approximate gravity reading if you find yourself in the same situation. If I broke my hydrometer/refractometer in the middle of my brewday I certainly wouldn't head out to the LHBS to purchase another one right away. Quick thinking and a good idea IMHO.

P.S. You spelled "precise" incorrectly...

 

Yeah, I skimmed over the introduction at first; I came back to say that the reason he wound up doing this makes a lot more sense than trying to avoid using a hydrometer.

Also, what he did (weigh the cylinder full of wort then again full of water and subtract) is a much better idea than what he said later (tare out the cylinder and assume the weight of distilled water)

 

I think I'll give this a shot on my next brewday to compare with my Refractometer readings. I've got a 60ml syringe that I can use for the measurements.