I'm doing something a bit different on my current project and I don't specialise in flooring, but I'm trying to develop my own thin "pseudoterazzo" floor made from resin, decorative sands and fillers trowelled onto the slab, which then gets polished with resin pads like a concrete floor. I'm having this problem where after grinding and polishing it, despite it being very hard and incapable of being scratched with even metal, my fingernails are able to mark it. Other surfaces of similar hardness don't do this and I can't figure out what these marks actually are. I tried wiping it down with various chemicals, even acetone in case the surface is actually covered in remaining resin. Even polishing it only with metal-bond pads created this effect.
My possible theories as to what this is are that it could be
-parts of the resin pads smeared on the surface of the floor when when rubbed distort and create a "scratch"
-organic material from my fingernail filling in the porous surface (currently checking if a penetrating sealer solves this)
-a sheet of "burned" flooring resin glazed over the top as a result of the polishing process which isn't as strong at the flooring itself (although I tried wet polishing it and still had the same problem)
This doesn't seem to happen on any other surfaces, even those of similar composition such as manmade stone benchtops, marble, or polished porcelain tiles. The thing I don't understand is that although the surface is extremely hard and resistant to mechanical scratching, my fingernails are able to leave marks.
Strangely enough, the marks buff right out again, more easily with water, which leads me to think that it's only my fingernails leaving organic trails.
This could be something really obvious but I don't specialise in flooring and I'm developing this system because I'm not aware of anything similar commercially available.
If you know what these marks are, please let me know.
Here is a video of the problem.