Boil time

[Starchild]

Hi everyone
I am in need of some help again!
Probably a simple question but non the less
one I can't seem to figure out...
How do you determine your boil time?
most recipes calls for about an hour but still how do
you determine that?
O yeah and is there any way of predicting final gravity...
You can work out your original gravity but can you work out
your final gravity...is there a way or do you just ferment until the gravity is stable?

Thanx a lot

 

[Yooper]

For extract batches you just boil for as long as your longest hop addition requires. In many recipes, that is 60 minutes but not always. Extract itself doesn't need a boil at all, as it's already been processed, so boiling as long as the bittering hops need is a good rule of thumb.

For AG batches, other things happen during the boil and generally 60 minutes is enough time for most of those chemical reactions to happen. Occasionally, there will be an ingredient that may require a longer boil (like pilsner malt) so a 90 minute boil is desired.

You can usually guestimate your FG based on the recipe ingredients, the mash temperature, the yeast strain's attenuation, and prior experience with that recipe.

 

[Starchild]

So is AG boiling time only dependent on ingredients? what will happen to a 1 hour recipe if I boil it for 2 hours?