Applying sealants

Sealants (apart from brushable types) are applied using a caulking gun, which can take a little practice to use properly. Before putting the cartridge into the gun, the tip tube may need to be cut off to allow the sealant to be forced into the nozzle. Once this is done, screw the nozzle back onto the tube then clip off the end of the nozzle at a 45-degree angle, using a sharp utility knife. The further down the nozzle you cut it, the larger the bead of silicone that will come out. If you only need a very fine bead, clip it off quite close to the tip as it’s
always easy to make the bead larger if required.

Slide the handle of the caulking gun all the way back, then slip the tube into place before pushing the handle of the gun in until it stops against the plug in the end of the tube.

To apply the silicone, turn the handle and then firmly apply constant pressure to the trigger until the silicone starts to flow out the end of the nozzle. To stop the flow, turn the handle until the pressure is released.

There are two ways of applying silicone – either ‘pushing’ the bead in front of the nozzle or ‘pulling’ it behind the nozzle. Try and produce an unbroken bead of silicone but, if necessary, smooth it out with a filling knife.

To create a tidy job, apply masking tape to both surfaces, creating a ‘valley’ where the silicone can be applied. As soon as the silicone has been applied, remove the masking tape. Alternatively, spraying the area with a fine mist of soapy water allows any excess sealant to be cleaned up effortlessly.


There is a wide variety of sealants, with many of them  referred to generically as ‘silicone sealants’, even though this isn’t technically always correct. Silicone sealants are primarily designed as a waterproof seal, making them ideal for around baths, basins and showers and roof spouting downpipes.

silicone sealants

When choosing a silicone sealant, select one that is designed for the right job (Roof & Gutter or Window & Glass), as these will have a different chemical make-up. Most silicone sealants are treated with a mould/mildew retardant, so they have improved resistance to those ugly stains that can sometimes appear in the sealants around your bath or shower.

Many are also resistant to paint, so take care when applying them or choose a pain table co-polymer sealant. Co-polymer sealants perform in much the same way as silicone sealants and can be used on surfaces that are damp or even wet, which is extraordinarily useful when working outdoors or in areas where moisture is a constant problem.

silicone sealants

Selleys has a wide range of silicone sealants, including the new 3 in 1, which are specifically designed for certain purposes, but one of the new additions to the range is Wet Area Speed seal, which is designed to cure quickly, to a point where it is possible to shower just two hours after application.
Ados also has a number of different silicone sealants available at Mitre 10, ranging from a kitchen/bath option through to a roof/gutter version and a window/ glass formula, as well as their All Purpose silicone. Selleys All Clear, a co-polymer sealant, also comes in a tin rather than the standard tube, so it can be brushed onto awkward and irregular cracks.


With the advent of both flexible and rigid fillers in recent years, putties have become less and less common but they still have a place. Glazing putty is still used when glazing wooden windows and doors, while woodfilling putties and other products like Selleys Plastic Wood are still available for a more traditional approach to woodworking.

One recent advent has been the introduction of two-part epoxy putties, the perfect example of which is Selleys Knead It. Knead It (which has a couple of different varieties) comes in a roll that allows you to cut off what you need and then knead the two components together to create a putty that can be used for a range of different tasks. Knead It cures to an extremely hard, durable finish and can be sanded, filed, sawn, screwed and painted when dry.

Foam fillers

When undertaking renovations or repairs to a home, it’s often easy to be left with quite large cavities where pipe work or ducting goes through a wall. These can reduce the insulating properties in a wall or ceiling and provide spaces that can be draughty and cold. It’s also possible that awkwardly-shaped cavities and voids (such as under the edges of sheets of roofing material) will provide a haven for birds to nest or vermin to make their home, so it’s a great idea to fill them and seal these spaces off. 

Foam fillers

 Expanding foam fillers, such as Selleys Space Invader or Polyfilla Expanding Foam, are an excellent solution to these difficult areas. Available in a spray can, expanding foam fillers can be applied through a nozzle into these gaps where they expand to fill the empty space. If it expands too far (through over application) it can be trimmed back with a sharp utility knife to sit flush with it surroundings.

Rigid fillers

If you have ever filled a nail or screw hole or had to repair a blemish in a wall, ceiling or on the surface of a panel, a rigid filler is the type of product you would have used. Normally these come as pre-mixed products in a tub or tin and can be used directly from the container and applied to the affected area with a putty knife, where they will cure (dry). They can be sanded back to match the surrounding area. In some cases, a second application of filler may be required.

CRC has a product called Builder’s Fill, which can be used on a wide range of materials, while Selleys has a variety of fillers including Permafilla and Rapidfilla, the latter of which also comes in a version called Coloursmart, which changes colour from pink to white when it has cured and is ready for sanding.

Mind the gap

Fillers and sealants are a necessity for your home workshop and can be used in a wide variety of applications. From filling nail or screw holes and fixing blemishes in the surface of panels, through to bathroom renovations, sealing up leaks in a gutter and filling annoying gaps around architraves.
There is a massive range of sealants and fillers available at Mitre 10, which can cause some confusion when selecting the one for the job you are undertaking. No need to feel overwhelmed, though, because a bit of How To knowledge will help you get what you need.

Flexible fillers

Flexible fillers are one of the most versatile on the market and are designed for sealing gaps where some type of movement will still be required. This makes it ideal for along the top of skirting boards or around door and window frames, which need that flexibility due to natural contraction and expansion. Although a wide range of flexible fillers area available for interior use, there are also a number designed for outdoor applications or where there may be high levels of moisture, such as in bathrooms or laundries.

Flexible fillers

The Selleys range of No More Gaps products has a number of solutions to your flexible gap-filling needs. One of their latest products – Selleys 3 in 1 – is a multiple-use product that seals, bonds and fills, so offers the versatility of a filler, adhesive and sealant in one tube. Ados has a flexible filler called Gap Filler, while Sika’s Fast Gaps Filler is also designed for this application. Another option is Bostik’s Fill-A-Gap, a
water-based, paintable, acrylic gap filler.

Flexible fillers

In almost every instance, you’ll find that flexible filler is paintable but it pays to check on the packaging beforehand. Generally, flexible fillers can’t be sanded so they require careful application to ensure the best
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