This product works because you are actually applying a thin layer of new grout atop the old. Like paint, the effect is immediate but dries quickly. I did not apply sealer though you certainly could. It’s “permanent” in the sense that it does not chip or wear away, but daily wear and tear/dirt buildup, especially in my heavy-traffic kitchen, requires a refresh every couple of years of the galley area shown in the righthand pic above. It takes me less than an hour to complete that area. I haven’t had to touch up any other area.
And, yeah, for the cost of a professional cleaning or having a professional do the Grout Renew, I’ll pay $20 for the bottle and do it myself.
Tip: The typical applicator top from a hair color bottle will fit the Grout Renew bottle. With the applicator top, I can squeeze a very fine line down the grout and then use a toothbrush to fill in with little spillover to the tile. Most of the videos show pouring the product into a small cup, dipping the brush in, and then applying way too much to the grout with a lot of wiping/cleanup, wasting a LOT of the product and making a bit of a mess.