unless they have been used a shitload, the core's of skis get stress fractures from normal use because of chattering and buttering, if there used enough they they get weak, thats why skis over time get softer. SO in conclusion if there used a lot they yes you can break them by buttering them. But i agree with bret ( ride1080) you cant break a normal new ski bu butttering inless your a super fat fuck over 300
"you only live once, Just Fucking go for it!!"