Did you know?
That there is no one way to make a bath bomb? Companies or makers all have their own way and formula for making them. Some just Fizz, others may add bubbles or soften the skin with oils and butters. You have to look at the ingredients to see what they do. Example a bath bomb made with a milk powder will add some bubbles but not the amount as one made with SLS, SLSA or Coco Betaine. They are considered skin safe surfactant's derived from coconut oil. Some people are sensitive to them though even in the small amount they are used in most products.
If you are looking for a deeply colors bath look at bath bombs that contain Lakes & Dyes. Micas are beautiful but they will not color the bath water like the lakes and dyes. Micas also have a habit of clinging to the sides of the tub if not used with an Polysorbate. So if you have a porous tub that needs resealing or you didn't scrub it down and oils and gunk from your skin are sticking to it. It will be more noticeable!
I swear by equal parts of Vinegar and (Blue) Dawn dish soap in a spray bottle. Shake together and spray the tub down and walk away for about 45mins. It wipes down easy and clean! This mix isn't as effective after sitting in the bottle for a few days so only mix what you need.