I have been told that keeping a mask on a Styrofoam head is bad for the mask. I use one but I cover it with 2 plastic bags and black nylon so to keep the mask safe and to give a nice blackout look on the eyes.
No one can say for certain, I think. Seems like an urban legend almost lots of people say it because the hero was on a Styrofoam head and it deteriorated, but that was more so because of the smoke sweat and dirt.
I kept my ToTs H2 on a styrofoam head until recently I used paper towels so the neck wouldn’t touch the floor. The mask hasn’t rotted at all and it’s 2 years old
The chemical make-up of styrofoam has been known to draw the natural moisture out of latex, which is essentially tree sap. That’s why it dies and decomposes. Now to say this doesn’t take a long time, well this can be true. I say, why take the chance. I stuff mine with grocery bags. Also, this I believe, has helped keep one of my 20 year old masks in tact after various use. Hope this helped.