How to seal around bath tub or basin
It is essential to have a seal around basins and bath tubs to prevent moisture access to furniture, walls and floors.
Silicone sealer or sanitary sealer is available in cartridges that are used in conjunction with a caulking gun, to apply sealer around the edges or bath tubs, basin and showers in a bathroom, and sinks, countertops and around hobs in a kitchen.
Remove old sealing
Removing old silicone sealant can be tricky depending on the surface. One method is to use the blade of a craft knife. Slide the knife blade behind and under the silicone with the blade against the surface. Take care not to scratch the surfaces. After slicing the sealant at both surfaces, use the blade to cut the silicone into sections. Place the blade back under the sealant and then lift it away from the surface. Grab the loose end of the sealant and pull it gently, you should be able to lift the section of sealant away fairly easily. You can remove any remaining remnants of silicone by gently scraping it off with the knife blade. Wipe clean with acetone (nail polish remove) to ensure the surface is absolutely clean.
Sealing a bath
For best results, fill the bath with water before you apply the silicone, as some baths give slightly when they are in use. If you seal the bath without water in it, then when you use the bath, it may stretch the silicone and eventually lose its seal. Apply a line of masking tape above and below where you will apply the silicone sealer. This will give you a nice, neat finish.
Good to know
In order to determine how much to cut off, measure the gap/joint to be sealed and cut the nozzle according to the size of the gap. For easy application cut the applicator nozzle at a slight (30-45º degree) angle, this will allow you to keep the nozzle tight against where the two surfaces meet. Puncture the cap on the silicone sealant tube with either a pair of sharp scissors or a craft knife.
Attach the nozzle to the tube by screwing it clockwise onto the thread of the tube. Pull the pressure rod back to allow you to load the sealant tube into the gun, then squeeze the trigger gently until the pressure rod goes into the base of the tube. Keep squeezing the trigger gently until the rod makes contact with the diaphragm. Don't squeeze the trigger too hard or the silicone will leak out of the nozzle.
Use tub and tile caulk for most bathroom sealing projects. Most tub and tile caulk is a blend of silicone and latex that offers the best features of both. Pure silicone expands and contracts with fixtures, like bathtubs, that can shift position. It is a long-lasting, effective sealant, but it is relatively expensive and cannot be painted.
Applying the silicone
Position the applicator nozzle against the surface, then gently squeeze the trigger until the silicone starts to come out. While applying gentle pressure to the trigger, move the applicator nozzle along the surface at a measured pace. Try to cover the whole surface in one stroke.
The simplest way to get a nice finish is to use your finger. If you want to avoid getting covered in silicone, wear disposable latex gloves. Wet your finger first to stop the silicone sticking to it, use a bit of saliva or some washing up liquid. Run your finger along the sealant to leave a smooth even coat.
To remove the excess silicone from your finger, use a sheet of paper towel. Trying to get silicone off your hands with water just makes things worse! Use soap and water to clean your hands only after you have got the majority off with a paper towel.