There have been some recent articles in ISCA about merit badges. One part of the discussion was questioning whether merit badges were made using silk thread. We brought this up a couple of years ago as we offered up narrow tan merit badges (circa late 1930s to 1945) that identified versions embroidered with silk thread and versions embroidered with cotton thread. This change over in thread types occurred sometime during the WW2 years. The collectors of adult insignia or youth rank badges have known of the thread difference for at least a decade (see Terry Grove’s books on Eagles or Paul Myers’ books). Some collectors of merit badges though have still been in denial. Unfortunately Terry and Paul’s work was ignored by some merit badge experts.
Well, as we have been preparing the auction of a very nice collar pin collection we opened up one of our favorite reference books Uniform Badges and Insignia the BSA published in 1933.
Going into the book, there is a section on merit badges. In black and white they note that the patches are embroidered in silk on khaki cloth. 
I am not sure what better documentation to come up with for those still in denial.
