Hello all, first post. Search function leads me to pages and pages of threads so I'm posting. Doing some reading I've gathered that when sparging an all grain batch, you're supposed to sparge until your gravity is 1.015 or so. I'm just wondering what magic happens in the boil to allow your post boil readings to be in a ferment able range (1.050 or higher) just seems a little backwards to me is all. Links, threads, personal experience all welcome. Just curious of the science behind it. Thanks, your average homebrewer
The 1.015 or lower reading is from your LAST runnings (or rinse), hence it is the weakest or has less sugar. What you have in your boil kettle is ALL the runnings which will contain more sugar and after boiling, have an even higher gravity. Low gravity on the last running could result in a higher ph and consequently more tannin extraction from the grain husks (not a good thing).
