Technically not a guide, but the handy preview on the right should hopefully help understand the effects of adding different chemical mixes to your explosive (or otherwise) assemblies!
You need to be signed into your Google account to make a copy of this sheet for yourself to edit.
Will not work in Microsoft Excel, uses several helpful sheets-specific functions.
You can select up to 6 different chemicals for your payload by simply typing the first few letters of a chemical in the light-blue chemical column, and using the ‘Tab’ key for auto-complete, then entering the amount of that chemical in your assembly immediately to the right.
All the container properties are adjusted by selecting which assembly you are using in the top-left corner of this light-blue box.
Thanks to @Doubleumc for a working example of an explosive falloff grid.