Two different hydrometer readings?

So I fill up my wine thief enough so that the hydrometer is free-floating, and it gives me a reading of 1.010.

If I put a couple more inches of beer into the wine thief, it gives me a reading of 1.004.

I THINK the 1.004 reading is correct actually. It was at 1.010 a while ago, and I turned off the temperature control in my room. I'm guessing the elevated temps gave the yeast another fermentation cycle and dropped it down to 1.004. This would also explain the slight amount of phenols present in this brew.

Any ideas on why this would happen?

In my case the hydrometer is too wide to fit in the thief. I can get a reading accurate to about 0.020 (which is useless) in the thief, but if I drain into a measuring cylinder (which has a larger ID) i can get an accurate reading.

-a.

size said:

I turned off the temperature control in my room. I'm guessing the elevated temps gave the yeast another fermentation cycle and dropped it down to 1.004. This would also explain the slight amount of phenols present in this brew. Any ideas on why this would happen?

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You have to correct the reading for temperature. Raising the temp will gas of C02 without any fermentation.

Try shaking the sample to de-gas it completely.