As Fasta said, don't spray your semi-perms. They all CAN be applied by spray, but there's no need. For one, you will always get wastage. Even with a very well setup HVLP gun, you will always waste at least 25% of your material. That's just how it is.
And somewhat more importantly, it just isn't needed. Semi-perms don't build a film, they evaporate. They are a polymer suspended in solvent, so when you apply them the polymer stays in the microporosity on the surface of your tool and the solvent evaporates. This makes spraying totally redundant, as the only reason to spray any material (paint, gelcoat, PVA, etc) is to get a smooth surface film. With semi-perms there is no surface film, so you can just wipe it on and it will leave no trace on your substrate.
And lastly, over application is detrimental to both your tool surface and the release agents effectiveness. With semi-perms you want to apply them so thinly that they only just wet the surface before evaporating. If you were spraying, this would be quite difficult to achieve.
The exception would be if you are doing something VERY large. A 50 foot boat hull for example you might question whether wiping it on would guarantee full coverage, not to mention the time it would take. Even then, I've seen a local company here prepping their moulds for a boat hull, and they just employ a team of people to cut down the work load, and apply the release agent strategically to ensure coverage.