Selecting infrared non-contact temperature sensor
Surface Material -  Emissivity Coefficient, ε


Glass, Pyrex  0.85 - 0.95 W/m2
SS, polished  0.075   W/m2
q = ε σ T^4 A  


q  = heat transfer per unit time (W) 
T = absolute temperature in Kelvin (K)
A = area of the emitting body (m2)   



The thickness will affect heat loss to ambient while container heats up to inside temp and will have a temperature gradient across thickness dependent on rate of lost heat (W/s).