Hydrometer measurements

I have been wondering about the low original gravity (OG) for the ESB - 1.035. I did not have a specific figure in the recipe for the OG , but given that the wort had six pounds of malt syrup in there, I expected an OG something more like 1.045-1.050 - based on insight from reading backed up by expertise from Karps and Keystone. They said the final gravity (FG) of 1.010 sounded about right. From my reading, 1.015-1.005 is normal for a medium strength beer.

Allan at Karps suggested that the OG measurement might have been thrown off if the sample was well-aerated (which it was). All the bubbles in the solution could have lightened the reading. More to consider for the future - letting the sample settle before taking the OG.

John Palmer's How to Brew has a good appendix on using hydrometers that I will re-read before the next time, but there isn't much troubleshooting info there. Bodensatz has some good hydrometer info in one of their FAQs as well.