I'm finishing a table and bench right now. The finishing process for the tops of both pieces involves a hand applied dye, followed by a sprayed coat of Sealcoat shellac, then 2 or 3 coats of uncatalyzed EM-8000CV, then a final coat of the same product with the catalyst added. Because the table top is too large to easily move I'm not able to do everything in a linear sequence. I'm doing everything on the bench top and then I'll move the table top to my finish area, once, and do everything on it.
With a conventional spray gun cup I would have to clean it completely between the shellac and two different finish coats. But with the PPS system all I have to clean is the gun body, which is fast and easy. The removeable bags/lids allow me to just pull them out of the outer cup and cap them for later use. Here you can see the bag of shellac and the uncatalyzed finish coat capped off waiting for use a day later.
John