Ok, after using the product on a trip to the chilly White Stag Rally in Beatty NV this past weekend I guess I have a few comments.
Preparation - Simple enough. Put a few drops (I did WAY too many) on the inside of the visor after first making sure it's clean. I smeared mine around with my fingers to get a good coating. Then buffed off with a microfiber cloth I had laying around. It was clear when done, no haze, etc.
My helmet - Schuberth Concept 2 with the factory visor that has a anti-fog treatment already applied. I know this because as has happened to others some of the treatment has peeled off, mainly in the area right above my mouth/nose, which happens to be the worst fogging area. On a normal moist cool NW day the visor fogs badly and actually collects mucho condensation right in this concentrated area. The Schuberth helmet has a great feature that "pops" the visor out from the mount points on each side (one side alone or both) and moves it slightly away from the helmet. This helps greatly in keeping the visor clear, but depending on wind conditions can cause a lot of noise in the helmet. It obviously also allows water to leak in the helmet if it's raining. I pretty much cannot ride with the visor fully closed if the temp are below about 40deg without it fogging. It's a very well sealed helmet. If it weren't for the excellent retractable inside sun-visor I'd be looking for something else. I'd love to try their new C3 but at around $800 shipped from the U.K. it's not an option.
Testing - My trip started off cool and got colder as we headed south through Oregon and into N. Cali. When we stopped for lunch in Shasta City there was feet of snow everywhere except on the road itself. It was COLD, but dry. I first tried running with the visor fully closed but it fogged up. But running with one side popped it did great, except for the area where the factory treatment had flaked off. On the way home we saw temps down to 22 deg. Breathing out slowly I could fill the inside of the helmet up with what looked like smoke, with it floating around in the helmet. Very weird looking, it would just kind of hang there then get sucked out the one side that was popped. But it didn't collect on the visor, unless I closed it all the way.
Final Thought - For me on the C2 helmet, the stuff is working. I didn't need to wipe the visor at all until it got dark on Sunday night (3.5 days of cold and moist riding). When I did wipe the visor it was because I could see a bit of haze on it and it was distracting in the oncoming headlights. Once I wiped it off it was good the rest of the evening. I should also mention I purchased and installed a Pinlock Universal kit and installed it on a spare visor I had. Last year it seemed to work great. This year it has not been as effective for some reason. So I applied the Clarity treatment to the side of the Pinlock shield. But I didn't get a chance to swap it out on this trip to try it out. When I do I'll add some more comment here. So, am I happy with the Clarity product? I'd say yes. I think for me it's going to be an improvement, even if it's not perfect for my particular helmet.
Obligatory photo, helmet and visor in action. Notice the fogging to the right of the red pin, the area where the factory treatment has peeled off.