No. 1 Paperhangers Knife

I recently acquired this Knife.  It is 18 cm long, and the faded label appears to read “RIDGEL”, then “No. 1 Paperhangers Knife/ Made in U.S.A.”  The paint decorating the handle is quite spectacular, I’m guessing it is an oil based paint, but am unclear how this complex, tiny pattern was formed – the black paint appears to have been spun or dripped onto a turning handle? Any information is appreciated.