The key to fixing the problem we are discussing here is to ensure that every last bit of mould is removed, and that the repair is confined as closely as possible to the problem area.

After all… you don’t have you car completely resprayed because some idiot pushed a shopping trolley into a door and scratched it.

One tube of white mould-resistant bathroom sealer; soapy water.


  1. The first action is to cut the existing seal about 8mm on either side of the problem area. Make sure you cut it right down to the basin surface and the tile surface as well.
  2. Now use needle-nose pliers to pull away the sealant between the two cuts you made. Making the cuts ensures that you confine the repair to the specific area and you don’t end up having to make an extensive repair after pulling away too much of the sealant that is still perfectly OK. You also avoid jagged edges to the repair and possible lifting of existing sealant – under which mould could grow.
  3. Use tweezers to really get in and remove even the smallest bits of contaminated sealant – i.e. any sealant that has black mould on it. Once you have removed every bit of mould, give the bare area a spray of mildew killer, leave it for a few minuted, then use a brush and clean water to totally clean the area and finally dry it thoroughly with a dry cloth and paper towel until it is all perfect dry… you could even use a hair-dryer as well to removed even the last vestige of moistness.
  4. Here are some of the mould-covered bits we removed.
  5. Now apply masking tape along the edge of the basin and on the tiles above, and also to the left and right of the sealant you have removed, but about 3-4mm outside of each cut you originally made on either side. This will ensure that though the new sealant won’t end up being applied all over the place; it will overlap the repair area and the cuts you made.
  6. Now to apply the new sealant… you can use the nozzle supplied with the product, but a toothpick works also works well… save the nozzle for some future occasion.
  7. Use the toothpick to work the new sealant deeply into the repair area.
  8. Use the tip of your finger to force it in even further. Then apply more sealant and with the tip of your finger moistened in soapy water, smooth the repair.
  9. Now remove the masking tape.
  10. Re-soap your fingertip again and gently and lightly smooth the sealant once last time… this will get rid of the ridge left by the edges of the masking tape and in doing so will not only make for a seamless repair, but also remove any sharp ridges on which new mould can grow (even though the sealant you applied is mould-resistant, mould is very persistent.)
  11. The completed job… it is very difficult to spot the repair even when you know where it is.

Project guide

Skill level: 1

Estimated time: 30 minutes

Cost: R40-50… depending on the cost of a tube of sealant at your local Mica.

Assistant: No

Tools required:

Utility knife, masking tape, needle-nose pliers, tweezers, soapy water.


These materials are available at Selected Mica Stores. To find out which is your closest Mica and whether or not they stock the items required, please go to the Mica Store Locator find your store and call them. If your local Mica does not stock exactly what you need they will be able to order it for you or suggest an alternative product or a reputable source.