Drying sieves, melting flasks

I was going to expound on advantages of using high-temperature dry bath made of graphite flakes – cheap, good thermal conductivity, easy to clean, soft and shiny, does not scratch the glassware – and so I took this picture of half kilo of sieves baked at 380 C under vacuum, on a heating mantle filled with graphite flakes. (Btw, the thermo-probe on IKA stirrers really goes up to 400 C).

Only when I finished and cooled my sieves, I saw that the flask softened from overheating and its bottom got sucked in. Now we have a 2L Pyrex vase in our office, with a 24/40 joint on top…