How can a full boil be done, but still have a late edition extract?
You add an amount anywhere from 1 pound to half your extract in the initial boil....following the recipe for the hop additions, then at around the 15-20 minute remaining mark, you add the remainder of the extract.
The early extract is to help your hop isomeration.....but if your recipe called for any steeping grains, you can even skip the early extract addition and go for the total late, especially if, as some recipes call for there is a bit of two-row (Like kits from Austin Homebrew).
When I am formulating any extract with grain recipes I ALWAYS base it around Extralight DME, then I get all my flavor and color complexity from my steeping (or partial mashing) grains. That way you get to use more and varied grains.
For example, let's say you are making an amber ale....If you based it around amber extract, you have very little room to get complexity from roasted or crystalized grains.....you run the risk of muddying the flavor and ending up too dark for your recipe.....
Staying with my Amber example...The Srm range for that style is SRM: 10 17 so if your base extract
already puts you into 14 srms, you son't have much room to move around it....you may be able to sneak in a pound of crystal 30 let's say in it.
But if your Extralight DME has a color of 5 SRMs, you can really get into the recipe and play around with different combinations of grains until you get into the right color and Og range for the style.
It's kind of like making model airplanes....remember the "snap together" types that you started out with? You had maybe 8 pieces; 2 body halves two front wings, 2 rear wings and maybe 2 pieces for a cockpit, or two pieces for landing gear...
But if you got one of those 500 piece b52 bomber kits....you had a much more complex final product.