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Touch up silicone joints

Old joints in the kitchen and bathroom are a nightmare to clean. They get more difficult to be cleaned properly as the years go by and often cause the swift development of mould due to small leaks. Water penetrates behind the shower tray and mould cultures find the ideal breeding ground in the humid, warm environment. 

Which silicone?

So-called sanitary silicone are available on the retail market for interiors and especially for use in bathrooms. It is specially designed for wet rooms and in most cases come with built-in mould protection. It is also extremely resistant to detergents and very elastic. This elasticity is important because shower trays in particular are not completely rigid and can move when a person steps on it. Sanitary silicone is available in a wide variety of colours. It does not always have to be white. 

My advice: Steer clear of cheap silicone. This often has the unpleasant property of shrinking more than better quality branded goods, which means it has to be replaced faster. This is penny wise and pound foolish.


Use a multifunctional tool to cut out the old joints. Alternatively you can also use a cutter knife. There are also special cutters (Fugenhai) on the market that make cutting out the silicone slightly easier. It is important to completely remove all silicone residues. This works quite well with the multifunkctional tool or a cutter knife. If you use a cutter knife it is best pulled along the joint at an angle, flush with the entire length of the blade. When you pull your fingers over the places where the silicone joints were and you still feel some bits of silicone, you can also use silicone remover. Apply this special cleaning agent to the old spots where the silicone was, wait for the contact time to pass and then properly wipe off with a cloth. The best time to use the mould remover and brush (follow the manufacturer's instructions) is as soon as you see mould stains in the joints. Once everything is clean, it is time for the caulking gun. Place the cartridge in a caulking gun, cut it open and screw on the spout. Use the cutter knife to cut the spout off at an angle. Depending on how big your joints should be, the hole should be between 3 and 5 mm. 

My advice: Do not cut the spout opening too big. You can always cut the opening bigger later.

How big should a joint be?

Of course, this depends on how big the spaces or rather the gap widths between the individual connections are. As a rule of thumb: about 2-3 times the largest gap width. As the gap width is rather irregular in most cases, use the largest space for the calculation, so that the whole joint have an even appearance.

Injecting the joint

The silicone is now injected into the joint. Hold the cartridge at a slight angle to the joint and apply pressure to the cartridge with the trigger. As soon as the silicone starts to flow out, keep applying even pressure and fill the joint without stopping. The more evenly you can apply the silicone bead, the better the gap can be smoothed afterwards. Release the mechanism with a small lever on the pusher when you reach the end or when you have to remove the cartridge. Because if you don’t, the silicone will flow out uncontrollably and you will have to remove the remains later. 

Smoothing the joint

You can use your finger or better still a so-called rubber profiling tool to smooth the joint. The rubber profiling tool costs only a few euros and gives you clean and even joints. As the rubber clings to the right and left of the joint, you can skip the tedious task of masking the sides with masking tape. The profiling tool is available in different profiles, but I recommend a semi-circular profile. Whether you use your finger or a rubber profiling tool, it is important to moisten it with lye (some detergent with water). This prevents the silicone from sticking to the tool or finger allowing the silicone to be wiped off leaving a nice and smooth joint. Do not apply too much pressure when using your finger, but stroke the silicone until it’s smooth. 

Now leave the silicone to dry. How long that takes varies from manufacturer to manufacturer. Therefore, take note of the relevant information provided by the manufacturer and always follow the instructions. As a rule, drying takes about a day.

By the way: Even if your joints are not 100 % smooth, they now look better than they did before. Above all, they are usually leak tight again and water cannot penetrate where it does not belong. In my experience, only us handymen see the not so perfect spots. So don’t be afraid that you will not be able to do it!

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