If I have a recipe for a beer that I'd like to simply make bigger, what should be taken into account when scaling the recipe?
Imagine I have an amber ale recipe that I like. It comes in with an OG of 1.050 and an FG of 1.015, which is about 4.5% abv. Now imagine I want to boost this recipe to get it to about 8% abv. Should I just up the total amount of all grains (or extract) used, keeping the percentages the same? Would doing so affect the color? What about hops? Should I shoot for the same number of IBUs, or should I up the IBUs to account for it being a lot maltier?
I know I can play around with recipe software to figure out how much of each ingredient to use to hit the same color & bitterness, but that won't tell me if the recipe would "work." Have you scaled recipes in this way before? How did it work out?