Sealants are used to provide a waterproof seal around sinks, basins and other fitted items that may be splashed by water.

Fillers are used to fill small gaps between the wall and cabinets, so that there is no visible gap remaining.

Some people refer to sealants and fillers as caulks or caulking compounds, and call the tool that holds the cartridge a caulking gun.

The word 'caulk' dates back to the days when boat hulls were made of wooden planks and had to be sealed with fibre caulking to make them waterproof.

There are dozens of different products on the market, each of which has a particular formulation designed for specific uses.

Some sealants and fillers have anti-mould additives, or chemicals that make them more flexible, or bonding agents that help them to stick better to certain materials.

They can be grouped into three main categories, as described below.

Solvent-based silicone

Silicone is waterproof and flexible, and bonds well to glass, metal, ceramic tile, and porcelain. It's typically used to seal bath tubs, shower screens, vanity basins and stainless steel sinks. Because it is highly weather resistant, it's also used by other building trades to seal roof guttering, downpipes, flashing, vents and window glass.

One of its main disadvantages is that it doesn't stick well to timber. It can also be difficult to work with, and requires solvents to clean up. Most silicone sealants can't be painted over; however, they are available in a range of colours, including translucent.

Water-based caulks

Water-based caulks are flexible and able to be painted over. They are also easier to apply than solvent-based silicone, because the excess can be wiped off with a damp cloth. Some water-based caulks contain silicon, such as Selleys 'No more gaps', which is used widely as a gap filler in bathrooms and kitchens.

However, unlike the solvent-based silicones, they are not fully waterproof and are not suitable for damp locations, such as shower recesses or other areas subjected to a lot of moisture.

Polyurethane

Polyurethane bonds well to concrete, metal and timber. It can withstand harsh weather conditions, abrasion and joint movement. Polyurethane can also be painted over, particularly with acrylic paints. It is often used in high traffic areas, such as on floors and driveways.

On the downside, polyurethane is toxic and emits fumes while it is being applied. It also needs to be cleaned up with a special solvent.