I have noticed several times when I want to change a piece of gear in my build that has already been masterworked that after salvaging the old item, I cannot masterwork the new one to the same level with the available materials. This is a cheap shot, Blizz, which wastes my time and sets back my progress because I have to farm more pit materials with subpar gear.
The law of conservation of mass–matter is neither created nor destroyed in a chemical reaction–applies to Sanctuary too, you know.