I've made quite a few WE kits and all used Bentonite. What criteria should I use to decide if Bentonite is needed? What could go wrong if I skip it?
This is an excellent question. In addition to other effects, adding bentonite before inoculation starts the clarification process sooner.
From a kit vendor's POV, this is very important, both in meeting customer expectations and in increasing sales.
Customer expectations? Sure! A lot of folks get a wine kit and visualize drinking Chateau Petrus 2 weeks later! Ok, kit vendors can't
quite make that happen, but they can guarantee that a wine can be bottled in 4 weeks. Starting clarification on Day 1 helps ensure that.
Sales? Sure! A beginner bottles in 4 weeks, and immediately opens a bottle. The faster we drink it, the sooner we'll buy another kit.
Bentonite and other fining agents are not necessary. Most wines clear on their own, given sufficient time. If you plan to bottle after 9 to 12 months, you can skip it. If bottling on kit schedule you want to clarify. In between? It's up to you.
When making kits, I use the fining agents. For red grape wines, probably not. White and fruit wines? I find they benefit from a fining agent.