Rager Hop Formula Clarification

Question

I'm coding up some personal brewing software, and I'm confused by the explanation of the [Rager Formula][1]

[1]: http://www.realbeer.com/hops/FAQ.htm l

What is meant by the term "boil gravity", Is that the gravity when the hop addition is made? I get the feeling Rager was testing against the pre-boil gravity..

Secondly, can anyone point me towards Ragers original article in zymurgy?

Answer 1

I recently went on a quest to understand hop utilization formulas for a service we're developing (plug: http://mybrewco.com) . Couldn't find Rager's original article the best was this Zymurgy article in 1997:

http://www.scribd.com/doc/47604590/zymurgy-IBUs

There's an excellent book by Ray Klimovitz that I found very helpful.

https://interactive.asbcnet.org/source/Orders/index.cfm?section=unknown&task=3&CATEGORY=BK04&PRODUCT_TYPE=SALES&SKU=25513

There was a lot that didn't sit well with me once I wrote the code and saw them in action. There are so many factors that impact hop utilization and most of these can't be controlled by the average homebrewer. I wasn't convinced it was worth the effort.