Answer: ANNEALED

AnswerCrossword Clue
ANNEALEDDid a glassblower's job, perhaps
ANNEALEDStrengthened by heating
ANNEALEDToughened, as glass
ANNEALEDTempered and rendered malleable.
ANNEALEDTempered, as steel.
ANNEALEDTempered
ANNEALEDHeated, as glass
ANNEALEDGot hot, then cooled off
ANNEALEDToughened
ANNEALEDTempered with heat
annealedANNEAL, to toughen (to make tough (strong and resilient))
annealedto toughen or temper (metal or glass)