All serious unknowns are bad for something that is characterizing a Null device.
On the other hand, I haven't yet tried to recalculate the dummy with a lower LWIR emissivity, using the reiterative values as a start point. Note that the drop in LWIR E should affect the total emissivity also, since LWIR is the primary emissive part of the total IR spectrum for alumina-like materials.
I will still be in Italy for about another week.
When back I want to follow some leads I have found about the thermal conductivity of castables.
Hope that this will result in bringing the internal temperatures of my simulations more in line with those measured on your rods and also in a better understanding of what is the main factor what determines the thermal conductivity.
However still a lot of other activities on my list.
So it may be a while before there is anything to report.
In the meantime looking forward to see recalculations based on lower LWIR emissivities.