You need 5 Geb's Compound Extract and 1000 Clinker to make 5 Priming Residue.
Priming residue reduces the warm up time of a Reactory from up to an hour to up to 3.75 mins, and reduces running time from 8 hours to 30 mins. Ktisibios claimed that timings for doping would be 1/16 of the standard values, but this is not the case for many alloys. Research is ongoing at Priming Residue
1 deben of priming residue is consumed when the reactory is fired. You will see 2 options for firings - "Fire Reactory" and "Fire Reactory with Priming Residue".