OG Increased Overnight?

[rmiranda]

I'm somewhat new to home brewing and all-grain brewing, but I had the strangest thing happen to me. I took an OG reading from my refractometer for an IPA that I was brewing.

I placed a small sample into a cup right before transferring it to my fermentor. The reading gave me an OG of about .068. However, the next morning I took another sample from the same cup and I got a .076.

I cooled off the sample before testing it the first time, but it was already in the upper 68. The second sample was probably in the mid-60's.

What are your thoughts?

 

[BargainFittings]

evaporation from the sample cup will increase the gravity.

 

[buzd]

Once there is alcohol in the fermenter, you need to convert from Brix to get an OG reading from a refractometer.

http://www.northernbrewer.com/learn/resources/refractometer-calculator/

Also, why would you pull a sample on the second day?

 

[BargainFittings]

They said the measured gravity is from the same sample cup, not the fermenter.

 

[rmiranda]

Thanks. Evaporation might be why.

 

[Brinck17]

Yes, Temperature can be the difference. As temperature decreases SG will Increase.

http://ucce.ucdavis.edu/files/repository/calag/tab4503p23.jpg