OG sample dropped 40 points in 12 hrs?!

[moses1]

I brewed last night and the wort OG (well-stirred) was 1.039 at 85 F (corrected to 1.042). I left the hydrometer sample out and two hours later noticed it had dropped to 1.020 at 72 F. The next morning it was 1.000 at 65 F.

Is this normal? Is it just fermenting super fast? It seems like way too much of a drop, too fast. The sample was taken before pitching the yeast, so any fermentation would be due to natural airborne yeast.

What's going on?

 

[david_42]

Shake it really hard and check again.

 

[storunner13]

The gravity dropped to 1.000? Sounds a bit fishy to me. It could have something to do with your high pitching temp. If the beer is going to ferment at 65˚, then it would be best to cool down the wort to that temperature before pitching. At temperatures above 75˚ the yeast ferment like crazy, so the quick drop is understandable.

 

[moses1]

Maybe I should be more clear. I'm talking about the specific gravity of the small sample (quarter pint or less) I took out for measuring the OG. I scooped this out of the wort and took a reading (1.039 at 85 F, corrected=1.042) just before pitching the yeast. This same hydrometer sample (without any yeast added) dropped to 1.020 at 72 F two hours later, and 1.000 at 65 F 12 hours later. I haven't checked the SG of my beer since then, and don't plan on it until transfering to secondary next week. I'm just curious why the SG of my hydrometer sample dropped so much so fast without any yeast added. Any guesses?

 

[storunner13]

My apologies. The part about not having pitched the yeast just slipped through my fingers...