This is the white wax as favored by Pete Hidy and James Leisenring from their book on Flymphs.  This wax was first mentioned by L Harrington Keene in his book Rhe Practical Fisheman in 1898.   Being a white wax it is less likely to alter the color of the threads especially the lighter colors.  This is a medium soft wax with medium rack.   Works great as a thread coating as well as on the Clark Dubbing Block and Composite Dubbing loops.