🫧 Forest Glasshouse: Glass Viscosity, Cooling of a Gather, Reheating and Annealing Limit (2D)

A gather of hot glass on a blowpipe cools in air, its skin stiffens, and it goes back into the glory hole. Set the gather mass, start temperature, potash flux, furnace temperature, wall thickness and annealing rate, and see the viscosity scale, skin and core temperatures and the cooling rate the wall can survive. Four in-page numerical checks.