I assume that Alain Cloutier (big up for this great musician who plays Weiss wonderfully!) refers to Savarez Alliance KF, which come in about each and every diameter and lenght. The wound strings are indeed available either in silver or copper, and both are OK for early instruments; silver may sound a little brighter than copper, which has a more intimate sound, as stated by Alain.
So, searching online will surely get you more results with the keyword "alliance kf".
Hope this helps,