I recently purchased the Grex Tritium airbrush (fitted with the 0.5mm nozzle) and wish to report on it. I think most people use an external mix airbrush, where the cocoa butter does not pass through the body of the airbrush but is mixed with compressed air externally. I have used a Badger, and recently used as my regular airbrush a Paasche; both of these are external mix. The Tritium is an internal mix device, and I was nervous about clogging up the brush constantly with cocoa butter passing through it. In actuality that is not the case at all. I purchased a 0.7mm replacement nozzle to provide the largest available needle/nozzle for the cocoa butter to pass through. Replacing the 0.5 with the 0.7 was fairly easy. An internal mix airbrush requires more compressed air, so I knew my little Iwata Smartjet Pro (1/8 HP motor with top pressure of 35 PSI) was not going to be adequate. Grex sells a compressor for the Tritium (it is rebranded from another company, California Air Tools). They were phasing out the 1 HP model and so sold me a 2 HP one at the same price. A 2 HP compressor is an entirely different beast from the Iwata; its increased power is impressive--and a little scary for a mechanical-challenged user like me. But fortunately my nephew showed me that it was not as frightening as it looked, and my first time using it alone went without a hitch. This compressor is very quiet, as these things go. In these comments I am using space on the compressor because my conclusion is that the compressor makes all the difference in using an airbrush for cocoa butter.
The good thing about Grex is that they are aware of the food decorating crowd out there; they have a whole series of videos on various decorating techniques, mostly for cakes. Their tech support people are so responsive and I consulted them so often that Gmail now doesn't show the whole thread with my questions and their replies unless I specifically request it. Grex never failed to be responsive (usually within a few minutes) and to be sympathetic to the special needs of chocolate making. In explaining to me how to add a moisture trap between the compressor and the airbrush, one technician even took the time to set up the whole system (hoses, attachments, adapters, everything) and take a photo of it with every part labeled. I have never encountered tech support this good.
The Tritium setup I used had the cocoa butter in a container attached above the airbrush (not in little jars with siphons as I had been using with the Paasche--although the Grex can be adapted to use siphon-feed jars). This setup provides the most direct flow of cocoa butter to airbrush but does require a whole new system of preparation for airbrushing. I had the cocoa butter in temper in a Pyrex container (which can be microwaved and heated or cooled over water) and spooned it into the metal cup on top of the airbrush (I purchased larger cups than the ones that come with the airbrush so that I wouldn't have to waste valuable time refilling the cup so often). This process can get messy! But it really worked. The cocoa butter stays liquid much longer than it does when it is in an attached glass container and traveling through a siphon. Yes, a heat gun is still required from time to time to keep the cocoa butter liquid, but I could spray several molds without stopping. I learned a lot from this first session and now know to get a little stirrer to keep the cocoa butter from hardening in the bottom of the cup. But it does work much better than any external mix airbrush I have used. Changing colors is easier than I anticipated: You simply turn the cup (still attached to the airbrush) upside down above the cocoa butter container, drain out as much as possible, then wipe with a paper towel (again, this idea came from Grex tech support).
I had mistakenly thought the Tritium could be used on its own to splatter a mold. I saw a video featuring Salvatore Martone using a Grex Tritium to splatter, but when I mentioned this to Grex support, they pointed out what I did not notice in the video--that the chef is spraying the cocoa butter onto a little spatula or stick, and from there onto the mold. I tried this and had some success, though I will need a lot of practice to get it right. I think a spray gun (such as the Fuji or a Wagner) can do splatter without further equipment, but an airbrush cannot (though an airbrush can splatter with regular paint).
Final comment on customer service: Grex does not sell its products directly. I found everything I needed with Jerry Carter Airtools, and Jerry also provides excellent service and guidance. He even asked to see photos of the work I have done with chocolates.
Prices: Grex equipment appears to have the same prices everywhere. The airbrush was $209, the 0.7 nozzle $68, the larger cups $19 each, the compressor $299. Yes, it's appreciably more expensive than something like the Paasche I have. It does, however, do a better job in a shorter time and with less aggravation than any external airbrush I have used. It does not do all a Fuji can do, but with my limited space and the number of chocolates I produce in a batch (so far the most is 900 pieces), I think it is the most satisfactory and the cost is less than for the Fuji system, which even companies that sell paint gun types of sprayers have told me would be overkill.
Final verdict: I am very pleased with the Grex Tritium and would certainly buy it again. The added power of the compressor makes airbrushing almost (!) a pleasure.
Feel free to contact me with any questions.