Re: Mixing paints
Mixing different sheens is a very slippery slope. What is your plan when you run out of paint, you're not going to be able to run down to the store and pick up another gallon, and unless you measure your paint to know how much of each you are mixing, there won't be any way to "custom mix" another batch when needed.
As far as "can" you mix different sheens of the same brand, yes. Can you mix different brands/sheens, yes, but not recommended. The differing formulations of different brands is going to drastically change the appearance of the final product, and can affect the durability of the product as well. If you must mix, stick with a single brand.
Mixing sheens won't affect shelf life, that will depend upon the container it is in and the quantity left when stored. A full gallon of paint will store for a longer period than an inch or two in the bottom of a can.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!