Sealants and fillers
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.
Learning activity
Audio 7 (mp3 |6|KB)You've probably seen the huge range of sealants lined up along the wall at your local hardware store or building supplier. The particular brands that your company uses will have been chosen because they are the best suited for the types of jobs you do.
Choose one sealant brand and have a look at the information written on the side of the cartridge. Answer the following questions
What is the trade name of the sealant?
What are its features? (That is, what sorts of jobs does it do best?)
Does it clean up with water or a solvent?
Share your answers with your trainer and other learners in your group.