Steve Demchak of Seattle, WA asked: "Does anyone know of a good product for putting a protective clear coating over water transfer decals on a powder coated frame? I'm concerned that anything heavy in solvent would wrinkle or eat-up the decal. Ideally, it would be brushable."
I'm not sure how terrible you mind having your frame look by brush applying clear over the water slide decals. You've going to have all sorts of things adding up to ugliness without even considering the level of beauty of the powder coat itself. One of the basic principles of a great looking paint job is to spray the entire frame quickly so the entire frame is wet at one time. Otherwise, there is going to be an obvious division between where the wet paint ends. The standard way to overcome this (if only painting a small part) is to sand the newly painted area with progressively finer sandpaper until it can be buffed out with special compounds - being careful of course not to cut through the clear to the decals. John Cherry, a framebuilder in Indiana, would sometimes like to make his power coated MTB frames look better and send them to me to be decaled and clear coated.
Anyway, the method I use to clear over water slide decals is: 1. apply decals and allow quite some time (a day or more) for the water to completely evaporate. 2. Sand the entire frame to give the clear ability to adhere to the surface. 3. Spray 5 to 15 coats of Urethane enamel (a polyurethane like Imron is probably too toxic to go directly over water slide decals) over the decals. 4. Sand the decal area so the entire frame is sanded. 5. Apply the final polyurethane enamel clear coats.
Water slide decals have little durability by themselves but would still be fragile if not protected by clear. I'd be really surprised if you could a decent look without using good spray equipment. You will still get good durability putting an Imron clear over a powder coat.