^^^^^^^^^^^
Dipping the ends into hot water is the standard method to soften them to ease push fitting. They firm up again on cooling. I remember taking a kettle onto the factory floor to do retro fitting of anti microbial versions of the pipes as a test. Our paste pumping system pumped a cellulose (plant based) type adhesive ( mixed and looked similar to wallpaper paste) but could get affected by pseudonomas bacteria. Fresh paste daily and regular flushing. The bacteria ate the paste and turned it into smelly water!
