Switching Reducing Agent and pH Combo When Sharpening Your Vat

Q: I made an indigo vat using iron and lime. Now it is time to sharpen my vat. Do I have to use iron and lime again or can I switch to a different reducing agent/pH combo?

A: You can use any common reducing agent/pH combo! e.g. iron/lime, fructose/lime, thiox/soda ash etc. You don't have to stick with the one you started with.