Hi @GreenElf,
You can repair these fine cracks using this Rust-Oleum 946ml White Gloss Tub And Tile Refinishing Kit. It is a two-part epoxy acrylic coating kit designed to renew and refresh bathtubs, showers, tiles, sinks and other bathroom surfaces without needing to replace them.
To apply it, you'll want to follow the instructions in the Technical Datasheet, paying close attention to the surface preparation steps.
You should start by disconnecting the tap and the waste so that you have clear access to the entire basin. If there is any caulk or silicone, it should also be removed.
You can then thoroughly clean with a bleach-based cleaner to remove any mildew, clean with a hard water cleaner such as CLR Bathroom And Kitchen Cleaner, then sand the surface with 400 Grit and 600 Grit sandpaper and remove dust with a vacuum or by rinsing.
You can then mix the two parts together and apply it to the entire basing with a brush or roller.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
