Hydrometer readings for bottling necessary?

I understand the rationale behind taking hydrometer readings up to the point of getting the beer in the primary. What I'm curious about is what utility it provides after that fact if you tend to leave the beer in the primary for 2-3+ weeks (like many people suggest). Most fermentation finishes up in the first week or so, correct? Is there a reason to take a hydrometer reading after 3 weeks, other than to simply know your final alcohol content? I know getting a constant reading for 3 days lets you know that fermentation is complete so you can bottle, but if the plan is to leave the beer in the primary well beyond that stage, what's the point of taking more readings?

Just wondering if it's a necessary step in many cases.

skelrad said:

What I'm curious about is what utility it provides after that fact if you tend to leave the beer in the primary for 2-3+ weeks (like many people suggest). Most fermentation finishes up in the first week or so, correct?

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Theoretically, yes....practically, maybe not. Every once in awhile, I still get a batch that might take over a week to fully ferment out. With novice brewers in particular: who might not use optimal amounts of yeast, aerating the wort, or having proper fermentation temps, is it more likely that the brew might even take a couple weeks or more to ferment out....

I don't think it is really necessary to get 3 readings for 3 days. I'm sure there are exceptions and it can be a problem, but I like leaving it sealed until bottling to reduce the chance of an airborne infection or something. I go for 3 weeks minimum before bottling and have never had a problem. Now, I'm sure I'll have a bunch of bottle bombs with my next batch for saying this, but I'll take my chances.

I basically agree ^^. I bottle at 3 - 4 weeks, and check the gravity just so I can see how it finished. The whole "same gravity for three days" routine is if you want to rush the brew into bottles at the earliest opportunity. I try to avoid that mindset (not always successfully I'm afraid).

When I did King Brian's Caramel Amber, it called for a pound of caramelized sugar and a low mash temperature. That thing chugged along for two and a half weeks, and eventually finished at 1.008. Good stuff!