I have had a violet-colored meluna classic cup for a year, and I had been cleaning it after each cycle in half-strength hydrogen peroxide (soaked for a few hours), which helped get the stains out. But gradually it became permanently stained an icky color that bothered me enough to buy a new cup (I bought a BLACK meluna classic this time, which kind of reminds me of a toilet plunger, but no stains for me anymore!).
But I noticed right away by comparing the two cups that the new black one is significantly stiffer than my old one.
Is lost stiffness just a part of cup aging, or might the hydrogen peroxide have softened the TPE material?
I'm not worried about staining anymore, so now my only concern is taking good care of this cup. Does anyone know what the least harsh method of cleaning is? Is it boiling?
Thanks in advance for your advice!