For a good wire drawing practise it is recomended to look for a patenting structure of 85% fine perlite and 15 % coarse or medium resolvable perlite.
It is convenient to have the temperatures of the furnace constant and adjust speed accordingly to the obtained structures.
Common temperatures are (+ -) 1000 oC on the furnace and 500 oC on the lead .
It is convenient to keep the first zones on 1000 oC , the soaking or stabilizing zones can be at lower temperatures.
The reducing and presure atmospher on furnace is very import to avoid lead drag out.