from what ive heard, the silver speckles have an adverse effect to either alcaline or acidic cleaners, i think they can turn black, can't remember which one though. stupid 45 year old brain. i can remember what i did in first year at primary but i can't remember where i put my keys, whats that all about.
A few years ago i had a chat on the phone with the guys at altro. they mentioned using a thin coat or 2 of metalised polish on the floor after cleaning if it was looking dull. telling me this could reduce the non slip properties by upto 30% but when i asked them if they would put that in writing you can guess the reply