One of my hobbies is optical fabrication, and various tests reveal the flatness and smoothness of surfaces. In ordinary life I see surfaces and I see the shapes and conditions.
Online, I often see high end guitars, Doubletops, and older classical ibnstruments, and in the reflections can see surface contours, bulges, ripples which are indications of stresses caused by bracing. That, I understand.
In less expensive models I sometimes see near perfect flatness which suggests machine made surfaces. I have a 1990 Washburn C40 guitar made by Cadiz in Spain which has a flat mirrorlike top.
A luthier question. What surface work is involved in creating a guitar top? Does custom hand work create the ripples and irregularities, and is it a result of fine tuning a top...thinning here and there to achieve a desired response that straight machine finish cannot achieve?
I attach a photo of my 1980 Ibanez Andorra GA400s which was made by Ryoji Matsuoka or one under him as they created the Andorra series. It shows fine rippled teture that would not result from large scale tooling like large sanding boards or belts.
When I see a perfectly flat soundboard on an inexpensive guitar it says to me “overbuilt, finish way too thick”.