Let me put an perspective in to two layer , one layer over sharpened , hybrid files.
I visited Victoria and Albert Museum site and I found there an article on restoration of Queen Elisabeth 1's virginal , spinet. Its a 4 octaves harpsichord , an musical instrument which was the predecessor of piano but small and mobile and lightweight. It has a sound of when you are playing a metal string guitar with heavy thick gypsy jazz pick with strong impacts. Piano is a hammering instrument to strings with spring attached hammers , harpsichord is a mechanism which cut the way of string with snaps.
Well , they try to restorate the decoration of it and found that there was two layers. First under paint layer is a gold folio layer strongly attached to the wooden panel and there is an top paint layer on gold.
All the falcons , lions and what ever chavellier stuff is applied on the top paint layer with scraching with needle. When the top layer removed with scratching , the bottom gold layer is effected also and deformed.
This is the trick , when the gold been scratched , it shines wonderfully with like lots of gold mirrors.
I find the similar thing at two layer , one layer oversharpened with edges, hybrid files , that quality.
Thank you for pms and have a wonderful sunday.