A rubber mask is a modeling mask that someone else mixed for you.
Instead of powder and a bowl, you get a pre-formed sheet of the same kind of rubbery gel, and an ampoule to go under it. You apply the ampoule, lay the rubber over it, and leave it for twenty minutes or so. It seals exactly as a modeling mask does, without the timing pressure or the washing up.
The cryo part is the interesting half, and it is the part most people skip.
Cooling can temporarily change the appearance of puffiness or redness and can make hot or uncomfortable skin feel calmer. Those are short-lived cosmetic and sensory effects, not treatment for inflammation or a skin condition. The rubbery mask simply keeps that cool, occlusive contact in place longer than a thin wet sheet.
If the manufacturer says the mask can be chilled, refrigeration can make the cooling sensation more pronounced. Room-temperature use still provides the rubber-mask format. Never freeze a mask unless the product directions explicitly allow it.
Getting it right
Follow the temperature instructions on the specific pack. If chilling is permitted, use the refrigerator rather than assuming colder is better.
Use the ampoule as directed. In a two-step kit it is formulated as the first step, while the mask keeps that layer in close contact and slows evaporation.
Twenty minutes is the usual instruction and it is worth setting a timer, because a rubber mask does not dry out and tell you when it is done the way a sheet mask does. It will simply sit there.
Expect a heavier, more occlusive feel than a cotton sheet. That sensation comes from the format itself and should not be read as proof that ingredients are being driven deeper.
Who it is not for
Anyone with a cold-triggered condition, and anyone who finds the weight of an occlusive mask uncomfortable. If skin is actively broken or freshly treated, check with whoever treated it first.
In the cabinet
Dr.Jart+ Cryo Rubber with Soothing Allantoin. The version that made the format known outside Korea, and the allantoin variant is the one to start with, since soothing is what the cold is already doing.