From Lost Fables Wiki
Binding chalk, also known simply as chalk, is a type of limestone which is frequently quarried from cliffs. It makes an excellent base for paints and pastes, both for alchemical purposes, and for general usage. Many magic-infused or alchemical war pastes are made with binding chalk, but it is also used for a wide variety of purposes the world over.
Gathering binding chalk is a very easy process. Anywhere there is chalk in quantity, simply set up a quarry to chop it from Gaia, and get yourself several tons of the stuff.
Binding chalk can be used for all sorts of purposes, depending on what one wants to do with it. War paints can be made using various other alchemical reagents, protecting the user from all sorts of specific threats. Further, it can be used with tainted blood or the blood of a demi-celestial and a thickening agent to create a paint or paste which can form a containing circle for summoning purposes. It can be made into magically enhanced grout which can greatly enhance the strength of the building it is made out of.