Replace Silicone Sealant around a Bath

The main purpose of the Silicone Sealant around your bath or shower is to provide a flexible barrier to stop water seeping into the gap between the fixture and the wall. If a non-flexible sealant was to be used, it would crack after just a small amount of use.

Once silicone sealant begins to get stained or go mouldy it is almost impossible to clean completely. It will also, over time, lose its adhesion to one or both of the surfaces and allow water to penetrate.

Whatever the reason you want to replace the sealant, this guide will show you how to achieve the best finished result.

Removing the Old Sealant

  • Using a utility knife and a small pallet knife, cut and scrape the old sealant away from the joint. If the sealant is very old, it may peel away quite easily.
  • If you can get the knife or scraper under the edge of the silicone sealant, you can often slide it along the edge and peel it off in large strips.
  • Take care not to scratch the wall tiles as you work. If the sealant is particularly stubborn, you can buy sealant remover which is brushed on and softens it.
  • If any sealant remains on the bath, shower or tiles, you can use a cloth dipped in white spirit to clean off the last bits. You don’t need to get all of the sealant out of the gap between the surfaces, but make sure you clean off the flat surfaces.
  • Finally, use a clean, dry cloth to make sure the whole area is completely dry. Any moisture in the surfaces or in the joint could stop the new sealant adhering.

Applying the New Silicone Sealant

You can buy silicone sealant in a variety of colours, and in a variety of applicators. The traditional method is a cartridge which is fitted into a metal applicator gun. The trigger of the gun is squeezed, compressing the canister and squeezing the sealant out of the nozzle. You can also buy silicone sealant in squeezable tubes and aerosol applicators. For this guide we have used the traditional cartridge and gun applicator.

The nozzle of the cartridge should be carefully cut with a utility knife at a 45 degree angle. Where you make the cut on the nozzle depends on how thick you need the bead of silicone to be. Cut a small amount off the nozzle to start with, test the thickness of the silicone bead on an old piece of wood and then trim off more if required.

Use masking tape to mask off both surfaces about 5mm away from the joint. You don’t have to do this, and it can be quite tricky, but it is the best way to ensure a neat finish. Place the tip of the nozzle at one end of the joint and squeeze the trigger of the applicator gun until sealant starts to come out. Slowly move the nozzle along the joint, applying an even bead of silicone along the full length of the joint. As the sealant starts to come out more slowly, squeeze the trigger again.

Check the instructions on the sealant canister to find the time you need to leave it before smoothing. It is usually about 10 minutes. While you are waiting, mix a little washing up liquid with a pot of water (this stops your finger sticking to the silicone). After the prescribed waiting time, wet your finger and use it to smooth the sealant along the joint. This helps to ensure that the gap is filled and the sealant has a smooth, concave surface. Wipe off any excess from your finger onto a rag as you go.

When the whole length of the joint is smooth and neat, carefully peel off the masking tape and throw it away. This should hopefully leave the strip of sealant with beautifully smooth and straight edges. You will probably need to leave the silicone sealant to cure for at least 24 to 48 hours (check the manufacturers instructions) before you use the bath or shower. The longer you can leave it, the better.