Preparing VCT (Vinyl Composite Tile), BCT (BioBased Composite Tile), and SPC (Stone Polymer Composite aka Stone Plastic Composite)
Existing tile must be structurally sound, firmly bonded, and free of moisture-related failures. Completely remove all waxes, polishes, acrylic floor finishes (where present), dirt, grease, and contaminants prior to coating. Failure to remove existing maintenance coatings may result in adhesion failure. These substrates generally provide a more favorable bonding surface than flexible vinyl flooring products. A small test area is recommended to verify adhesion before proceeding with large installations.
Do not apply over loose, damaged, poorly bonded, moisture-compromised, or heavily contaminated tile.
Remove all waxes and finishes using a commercial VCT floor stripper according to the stripper manufacturer's instructions. A swing machine (also called a rotary floor machine or low-speed buffer) equipped with a black or green stripping pad is strongly recommended. Intro video is linked here. Your work must lead to a uniform dull finish. A 60–80 grit sanding screen may be used to improve surface profiling and contaminant removal. Thoroughly rinse the floor and pick up all rinse water with an auto-scrubber or a squeegee+wet vac. DO NOT EVER ALLOW RINSE WATER TO DRY ON THE FLOOR!
Again, what you use and how you use it is ultimately up to you. I can’t take responsibility for your prep work, but I’ll share every link, tip and trick I’ve found in hopes that you are as successful as possible. This floor stripper worked really well for me - 4 stars over 95 reviews - $15.28
Home Depot generally rents buffers and sells black stripping pads
IF YOU’VE NEVER USED A BUFFER, PRACTICE IN THE MIDDLE OF THE FLOOR AND BE READY TO STOP IT.
The trick is to keep lifting the handle up and down to swing it left to right. Staying in one spot is next level when you are first learning.
Water should uniformly wet the surface without excessive beading. Persistent beading may indicate residual wax, polish, or contamination that must be removed before priming. If in doubt, prep more. Nearly all coating failures on VCT and similar flooring systems are the result of inadequate preparation, not coating failure.
Wipe with acetone. If you missed a spot, when stripping off the floor finish, you’ll discover it here. Acetone and scraping will remove contaminants, but it is generally best to get the stripper and buffer out if you find you did not do the previous step properly.
Verify the surface is clean, dry, and free of residue before applying CleanPrime.