On Sun, 27 Jan 2019 13:32:28 -0500, wrote:

I bought a house with a nice outdoor, flat stone tiled walk way.
Unfortunately the tiler/installer was "quite sloppy" in a few areas.
There many of the tiles now have a thin, but annoyingly Noticeble
coating "film" of concrete grout on the top.

I have tried coarse steel wool, with limited (slow) improvement. Is
there a better/ recommended way, to remove that concrete film? I
would really like all tiles to be fully visible, no film.

As previously mentioned, use diluted muriatic acid.
https://www.google.com/search?q=cleaning+patio+muriatic+acid
I did that to my parents patios and walkways many years. It worked
just fine but required some extra pre-cleaning and scrubbing to remove
some soaked in grease and dirt where I had previously rebuilt an
automobile engine. I don't recall exactly what cleaner I used except
that it was made for the purpose and supplied by the local hardware
store.

If your patio is made from flagstone, I suggest you apply a sealer
after neutralizing the acid and letting it dry:
https://www.google.com/search?q=patio+flagstone+sealer
After acid cleaning, the surface becomes rather porous and will absorb
and trap water, dirt, grease, mold, mildew, shoe scuff marks, etc. I
suggest you avoid the "wet look" sealer as it's difficult to keep
shiny.

This looks fairly accurate:
https://www.wikihow.com/Acid-Wash-Concrete

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558