Some Guy, can you compare the surfaces left by the spray can lacquer versus what I assume is the water based version you are spraying with the HVLP? I have been wanting to try the water based HVLP version, but right now there's no supplier that can reach me via a non-freezing route. I don't see a liter or gallon sized lacquer version for sale for spray guns, I think they discontinued those.
I assumed the properties I have been seeing with the can solvent spray would not carry over to the water version. For the most part I have not much liked aqueous varnish on papers. With careful technique a reasonably transparent surface can be had that eliminates bronzing and adds a lot of protection, but that still slightly hazes midtones and dark areas about the same as an uncoated baryta print.
What impressed me about the can stuff is how it seems to remove any barrier between viewer and print. One beholds an image through a window of perfect clarity. Sure you can see reflections, but not a trace of haze or masking. To get a better looking art piece I would have to go to something like (almost) zero-reflection TruLife acrylic and face mounting, which is a world-beating presentation at around 20 times the production cost.
This is what I use:
http://www.premierimagingproducts.com/pc_printshield.phpIt looks like water in the clear bottle, but it is lacquer. A very, very thin liquid much like ink and not normal lacquers you see from hardware stores. I shoot it with a Sata MiniJet gun and use a respirator and eye goggles. About 2-3 thin coats using about 2-3 ounces out of the gun for a 17x25 inch print. Clean up with acetone.
Their other stuff is the thicker water-based roller stuff (Eco Shield) which looks much like the Golden Clear Gel sold at most art supply stores too (Looks like white glue and dries clear.).
As to spray cans, they don't always spray well. The Marshall's SureGuard does, but it's expensive and probably like the Premier Shield in a spray can. The can cloud portioins and make the image soft which is annoying on glossy surfaces.
The best coating I've seen is using the Cone Gloss Optimizer with maybe two separate thin coats of 20K GO out of the K7 piezo printer using QTR. Little smell, and very even if you are unsure of spraying. Cheap HLVP guns I haven't had much luck either (Waggners) with so I had to use the Sata as the tips are changeable and the compressor's supply is water-free and consistent via a muffler, etc. much like an automotive spray gun setup.
SG