Original Gravity's?

[hamstringsally]

have done about 20 all grains now and have a refractometer and original gravity's are anywhere from 1.048 to 1.051 after boil. getting a pretty constant reading now throughout the brews and just wondering what the theory is with the readings to have a bit more understanding?

cheers

 

[manticle]

To have a bit more understanding of your question, you will need to clarify what it actually is.

So far - you have a refractomewter. You measure your OG. You brew AG.

What else?

 

[Wolfy]

'Original Gravity' is the specific gravity of your wort, measured before the yeast is pitched and fermentation starts.

It's used to help you calculate (once you know the final gravity) the alcohol content of your beer, and it also gives you an indication of your brew-house efficiency.

However, since the Original Gravity depends mostly on the amount of sugar in your wort, there is no reason to expect to the same for each beer you brew (unless you brew the same thing every time).

 

[hamstringsally]

cool. Im mainly doing pale ales and amber ales. I understand the part of taking a reading OG and then determining the FG but was brewing last night and saw the targets on my pro mash recipe and then looked over my notes and saw that mine always read to round 1.048 to 1.051

someone told me it can also determine brew-house efficiency. Not sure how to work it out though

details

4.5 kg ale malt
.3 wheat malt

mashed 17L at 66 deg for 60min. Batch sparged. (always pull around 11 Litres from 17. If I mash with 16 Litres I always end up with 10 Litres so I aways lose a about 6 litres through the mash).
sparged at 80 deg to make up 27 litres for pre boil amount

horizon AA 14%
amerillo AA 6%

horizon 60 min
amerillo 10 min
amerillo 0 min