transparent elastomer safety shields for laboratory glassware subjected to vacuum evacuation , and for electronic components , is disclosed . removable glassware sheaths permit viewing vacuum processes while protecting personnel from implosion hazards . removable sheaths also permit adding conventional heat transfer materials such as powders , strips , and fluids to the sheath prior to securing to the glassware to assist evaporation and sublimation procedures . further , the addition of thermally conductive nanopowders , such as copper , aluminum , and iron to flowable polymer formulations prior to curing into a solid elastomer , provides enhanced thermal conductivity for these transparent sheaths , and for “ see through ” heat sink potting compounds for protective covering of electronic components .