Karen, is the Wyandotte bantam partridge or Cochin partridge not double laced? Or both? I'll have to check it out more thoroughly. Should have to begin with.
no, they are not double laced... they are penciled...
in single lacing, the black (or blue/splash, as the case may be) is pushed to the outer edges of the feather. this involves 3 mutations. Pg pattern gene, Ml melanizing and Co Columbian.
the pattern gene provides the basic pattern required (as in penciled), adding melanizing makes the feather blacker, causing the marked areas to become wider and spread out closer to the edges of the feather (double laced), and adding Columbian pushes all the black pigment to the outer edges (single lacing).
penciling (patridge or silver laced)
Double lacing (Barnevelders, dark Cornish)
Single lacing (silver laced, gold laced, blue laced red)