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How to apply bathroom sealant

Freshly applied silicone sealant in a bathroom​

Overview

Over time, bathroom silicone sealant can become discoloured, mouldy, cracked or start to peel away from surfaces. Replacing old sealant not only freshens up the look of a bathroom, but also helps maintain a waterproof seal around showers, baths and splashbacks. Applying new sealant is a straightforward D.I.Y. project, and taking the time to prepare the area properly can make a big difference to the finished result.

Steps

1

Remove the old sealant

Use a utility knife or silicone removal tool to carefully cut and remove the existing sealant. Take care not to damage surrounding tiles, surfaces or fixtures. Remove as much of the old sealant as possible, as new silicone adheres best to a clean surface. Once the old sealant has been removed, brush or wipe away any loose pieces of silicone, dust and debris. Even small remnants can affect the adhesion of the new sealant and impact the finished appearance.

Wipe the joint thoroughly using methylated spirits or a suitable cleaner to remove soap residue, oils and dirt. Allow the area to dry completely before applying new sealant. Silicone should never be applied to a damp surface, as moisture can affect adhesion and lead to premature failure.

A person wearing gloves is using a clean cloth and methylated spirits to prepare bathroom surfaces before silicone application.

2

Apply masking tape

Apply masking tape along both sides of the joint, leaving an even gap where the silicone will be applied. This helps create cleaner edges and can make it easier to achieve a professional-looking finish, particularly for first-time D.I.Y.ers.
A person is applying ​masking tape around joints to help achieve a neat and professional silicone finish.

3

Prepare the sealant cartridge

Select a wet area silicone sealant suitable for bathrooms, laundries or kitchens. These products are designed to provide a waterproof seal and often contain mould-resistant properties to help keep the finished joint looking cleaner for longer. Sealants are available in a range of colours, so choose one that complements the surrounding tiles, grout or fixtures.

Load the sealant cartridge into the caulking gun and cut the nozzle at a 45-degree angle. Start with a smaller opening, as more sealant can always be applied if needed. A smaller nozzle opening often provides better control and helps avoid applying too much product when resealing a shower.

A person is trimming the silicone nozzle at a 45-degree angle using utility knife for controlled sealant application. ​

4

Apply the sealant

Before starting, test the flow on a piece of cardboard or scrap material to get comfortable with the pressure required. Hold the nozzle at a consistent angle and apply a continuous bead of silicone along the joint in one smooth pass. Moving too slowly can result in excess sealant, while stopping and starting may create uneven sections in the silicone bead.
A person is ​applying a bead​ of silicone sealant along a taped joint using a caulking gun.​]

5

Spray the sealant

While the silicone is still wet, lightly spray the bead and the silicone smoothing tool with a mixture of water and a few drops of dishwashing liquid. This helps the smoothing tool glide smoothly over the sealant and can make it easier to achieve a neat, professional-looking finish.
A light mist of soapy water is applied to fresh silicone to help achieve a smooth, professional finish.

6

Smooth the sealant

Run the smoothing tool along the joint using steady, even pressure in one continuous pass where possible. Wipe excess silicone from the tool regularly to avoid dragging it back across the finished surface. If there are small bumps, ridges or uneven areas, simply spray the area again and make another smoothing pass before the silicone begins to skin over. If a section has too little silicone or a gap has been missed, apply a little more product and smooth it again straight away. Working in small sections can help maintain control, particularly when tackling longer joints.
​A person is smoothing freshly applied silicone sealant using a smoothing tool to create a clean, even and professional-looking finish.

7

Remove the tape and allow to cure

Once the joint has been smoothed, carefully remove the masking tape while the silicone is still wet. Pull the tape away slowly at an angle to help create a clean edge. Check the manufacturer's instructions for silicone curing times before exposing the area to water. Most bathroom sealants require a curing period to achieve a fully waterproof seal. Avoid using the shower, bath or splashback area until the sealant has cured completely, as introducing moisture too early can affect the finished seal. Once cured, the new sealant will help protect against water ingress while giving the area a fresh, clean finish.
After curing, the new silicone seal leaves clean lines and long-lasting protection against water ingress.​

8

Looking for another bathroom refresh?

Check out our article on how to select the right shower head.
Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer.