Stir each time you use it or after it has sat for five minutes or more.  If you do not stir in between uses, it will dry mottled.

This glaze must be stirred all during the use of it.  If you do not, it won't dry clear.  It will have a milky cast.  (I usually paint 2, stir, paint 2, stir). This is great to get cookies to stick to each other. They will never fall off again.  I only coat the backs if it is to be eaten; both sides; if it's for a display.