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How to silicone a gap

Finished silicone seal neatly applied along the joint between a stone-look benchtop and matching splashback, creating a clean, continuous finish in the corner of the installation.

Overview

Applying silicone sealant is a simple way to create a waterproof seal around sinks, benchtops, baths and tiles, helping stop water from getting into gaps and causing damage over time. With the right preparation and technique, you can achieve a clean, professional-looking finish that helps protect wet areas from moisture and mould.

Steps

1

Prepare the area

Before applying fresh silicone, make sure all old sealant has been removed and the area is completely clean and dry. Remove old silicone and cleanClean the surface thoroughly using methylated spirits or an appropriate surface cleaner to remove any soap scum, dust, grease or residue that could stop the silicone bonding properly. Allow the area to dry fully before applying silicone. If you want extra neat edges, apply painter’s tape along both sides of the joint before you begin silicone application.
Hand wearing a black glove wipes the junction between a stone-look benchtop and matching splashback with a blue microfiber cloth to clean the surface before sealing.

2

Prepare the silicone cartridge

Load the silicone cartridge into the caulking gun and cut the nozzle at a slight angle using a utility knife. It’s best to start with a smaller opening because you can always trim more off later if a larger bead is needed. Once the nozzle is cut, use the pin on the caulking gun, or a skewer, to pierce the inner seal inside the cartridge. Before applying silicone to the joint, test the flow on a piece of cardboard to check the bead size and make sure the silicone is dispensing evenly.
Black-gloved hand uses a utility knife to trim the nozzle of a silicone cartridge while the cartridge rests on a stone-look benchtop beside a piece of cardboard.

3

Apply the silicone

Place the nozzle into the gap and apply steady pressure to the trigger while moving along the joint in one smooth, continuous motion This is a key step when learning how to apply silicone. Try to maintain an even speed and consistent pressure to help create a uniform bead of silicone. Avoid stopping and starting too often, particularly around corners, as this can create uneven sections or air gaps in the seal. If needed, slightly overlap sections to keep the bead continuous along the full length of the joint.

Apply only enough silicone to fill the gap evenly, as using too much can create excess mess and make the joint harder to smooth neatly. It’s easier to add a little more silicone where needed than remove large amounts once applied.

Person wearing protective gloves, glasses, and a dust mask applies a bead of silicone along the joint between a stone-look benchtop and splashback using a caulking gun, guided by blue masking tape.

4

Smooth the silicone

Once the silicone has been applied, lightly mist the area with soapy water to help stop the silicone sticking to the finishing tool and allow it to glide more smoothly across the surface. Use a silicone finishing tool to smooth the bead straight away, pressing the silicone firmly into the gap while removing excess product from the surface. Wipe the tool regularly with a damp cloth to help keep the finish clean and even as you work.
Black-gloved hand uses a blue silicone finishing tool to smooth a bead of silicone along the joint between a stone-look benchtop and matching splashback, with blue masking tape protecting the edges.

5

Clean up the area

After smoothing the silicone, inspect the joint for any small gaps, uneven sections or excess sealant. If needed, apply a little more silicone and smooth the area again before the surface begins to skin over. If you used painter’s tape, carefully remove it while the silicone is still wet to help leave a crisp edge. Clean away any remaining residue with a damp cloth before the silicone starts curing.
Hands remove blue masking tape from the joint between a stone-look benchtop and splashback, revealing a neat silicone seal along the edge.

6

Allow the silicone to cure

Once you’re happy with the finish, allow the silicone to cure fully according to the manufacturer’s instructions before exposing the area to water or moisture. Silicone curing time can vary depending on the product, room temperature and humidity levels. Avoid touching or disturbing the silicone while it cures, as this can affect the finish and weaken the waterproof seal.
Finished stone-look benchtop and splashback with a clean, continuous silicone seal visible along the joint after application and cleanup.

7

Successfully filled a gap with silicone?

Try replacing all your bathroom silicone with our guide how to apply bathroom sealant.
Health & Safety

Asbestos, lead-based paints and copper chromium arsenic (CCA) treated timber are health hazards you need to look out for when renovating older homes. These substances can easily be disturbed when renovating and exposure to them can cause a range of life-threatening diseases and conditions including cancer. 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 or visit our Health & Safety page.

When following our advice in our D.I.Y. videos, make sure you use all equipment, including PPE, safely by following the manufacturer’s instructions. Check that the equipment is suitable for the task and that PPE fits properly. If you are unsure, hire an expert to do the job or talk to a Bunnings Team Member.