I want to see if this can work or has been done by anyone else, here are my thoughts:
- make 9 1/2 gallons of wort with base grains, specialty malts and hops
- regular process: mash, boil, chill
- split the 9 1/2 gallons into 5 gallons and 4 1/2 gallons
- make a 1/2 gallon wort with dark specialty grains (steep or mash) on the side
- boil to sanitize
- chill to fermentation temps with ice bath
- add 1/2 gallon wort to 4 1/2 gallons wort to make 5 gallons
First batch would be an IPA, while adding the dark specialty malts to the second batch would create a BIPA.
I'm guessing theoretically this could work, wondering if anyone has other combinations they have tried.