I've done some french polishing on instruments and now I'm getting into aniline dyes on the surface under the shellac. I've used the bullseye spray can shellac with mixed results - when it works it leaves a (reasonably) smooth surface and the dye is well-sealed so I can french polish over the top without any dye smearing or coming through. However it's really hard to tell how old the spray cans are, and I've now had more than one instance where the spray shellac is clearly too old and refuses to harden. I mix my own flakes for french polishing, so I'm thinking a preval sprayer may be my best option. I bought one and tried it out with a 1lb cut - it sprays alright although the surface is a little bumpy. However I did see my dyes run a bit on the test piece, including a little black dye running over an inlay. I tried to keep the coats really light, but it's possible I sprayed too many in quick succession. So, am I missing anything here? Has anybody tried shellac in a preval? What's the recommended cut for spraying shellac in a preval unit? Any other suggestions? Thanks!