I Have an Omni on the way
To regulate air flow with the Omni, does one:
Use both the spinning mouthpiece and the carb at the same time when drawing?
Or set the airflow with the MP pre session and use the carb as preferred?
The Omnivap does not have a spinning mp. What makes an Omni an Omni is the threaded integrated mouthpiece/condenser unit.
The Omni airflow is adjusted by intentionally turning the mp that is threaded onto the Omni condenser.
By turning the mp clockwise you thread the mp onto the condenser threads which brings the two pieces closer together, shortening the condenser length and opening the airpath.
Turning the mp counter clockwise threads the mp away, lengthening the condenser to the extent that the beveled condenser end, enters the neck of the tip, cutting off the airflow.
So, you can adjust the amount of airflow by the degree with which you thread the mp on or off of the condenser. The idea is that you set it and forget it. Set your preferred airflow before using.
New Omnis may have a mp/condenser that is bit tight and difficult to adjust, so it can be helpful to pull out the mp/condenser and thread it on and off to understand what's happening and to initially set your airflow. Then lubricate the orings with a bit of spit and push the condenser assembly back into the stem.
With use the condenser will become easier to adjust. When adjusting the condenser AS it sits inside the stem, always check to make sure that the mp has not been pushed away from the stem. If so push the mp into the stem until they meet.
Set your airflow before using. Then use the air intake hole as desired. Everyone has their sweet spot. I like mine set tight in its longest position for satisfying mouthpulls.
Slightly off topic — is there an "official" way to clean the cap? I remember reading somewhere that an iso wash can lead to rust.
I'm not sure why you would need to clean a cap. The cap does not come in contact with resin containing vapor, only clean air passes under it. The parts that require cleaning are the tip and the condenser.
If you don't like the patina that results from repeated heating, I've heard that toothpaste works to polish and clean the exterior of the cap.
If you suck and blow, I could imagine the inside of the cap becoming soiled. If the inside needs a clean up, I would use an ISO moistened Q-Tip and swab the inside of the cap. Rinse thoroughly with water and dry completely before using.