dont do anything to it except wear it…you will appreciate the longevity of your top this will allow for…stretching, or even worse, cutting…will only lessen the life of your gasket…it will loosen up after a few weeks on the water.
They don’t stretch, they may loose a bit of strength due to deterioration but stretching just isn’t really a part of it. If you make a difference in fit by stretching you have probably just stressed the gasket and hurried up it’s demise.
Cutting can be done correctly and does nothing to shorten the life. Not cutting may be worse since the gasket is over stretched while your wearing it leading to premature cracking etc.
More likely than stretching is that you simly get used to the tightness. Mine always feels constrictive the first couple outings, then I just forget about it.
Cutting should be done by placing the gasket over an object like a pot or traffic cone until it is tight. Using a razor blade / box cutter trin just beyond one of the ridges that circle the neck. These are there to help guide you and are intended as cutting areas by the manufacturer.
Scissors tend to leave little knicks each time you sto and start, these lead to tears, that is why blades are better.
Yes they do loosen up. I have used my pelli case or if Im at home a traffic cone to lossen them up …this will not shorten the life span . My last gasket lasted for over 400 days of paddling. As stated above , lubricate with 303 protectent or there is a silicon based paste made specificly for latex gaskets and is available at Dive shops. Kepping it lubed up will protect it from UV and drying out and keep it from chafing your neck and it will slip over your head or wrists even if you are sweaty or wet.