The short answer: Sanitary silicone is available in well over a hundred colours – the big manufacturers match their ranges directly to the grout colour charts of Weber, Mapei, Sopro, Ardex, Kerakoll and PCI. The most reliable route to the right colour therefore does not run through comparing by eye but through the name of the grout used: look up the grout brand and colour, check it in the silicone manufacturer's assignment list, done. If the grout is unknown, the only option is a colour chart held against the original in daylight – and a trial joint at an inconspicuous spot, because silicone dries differently from how it comes out of the cartridge.
Why the colour of the silicone joint is so noticeable
A silicone joint is narrow, but it runs through the whole room – along the bathtub, around the shower, at every transition between floor and wall. If the colour is off, in the finished bathroom that is the first thing you see: a light or dark line that cuts up the surfaces.
With grey and white tiles that used to hardly stand out. Nowadays there are tiles in anthracite, sand, taupe, concrete look and wood decor, and matching grout in dozens of shades. That has turned the silicone joint into a visible component – and the choice of colour into a real decision.
A second point comes in: the elastic joint and the rigid mortar joint butt directly against each other. In the corners, at the transitions to the floor, along the bathtub, both run side by side. Every deviation in tone is directly compared there.
The safe route: via the grout
Manufacturers of sanitary silicone solve the problem by aligning their colour ranges to the common grouts. For every silicone colour there is a list of which grout colours of which manufacturers it matches.
In three steps to the right cartridge
1. Establish the manufacturer and colour of the mortar joint. It is on the sack or bucket, in the tiler's quotation or in the invoice – for example "Weber.fug 897 cement grey" or "Sopro DF 10 no. 22 Bahama beige".
2. Look it up in the silicone manufacturer's assignment list. The matching silicone colour is stored there. This assignment has been matched against the original and is considerably more reliable than any comparison by eye.
3. Note the colour number, not the name. Colour names such as "grey", "manhattan" or "beige" exist in several variants at every manufacturer. Only the number is unambiguous.
This works above all in new builds and fresh renovations, where the material used is still known. That is why it is worth noting down the grout information while it is to hand – at the first joint renewal in a few years it is worth its weight in gold.
When the grout is unknown
The more frequent case in existing buildings: the bathroom is twelve years old, the joint has to be renewed, and nobody knows any more what was used back then. Then comparison is the only help – but systematic comparison.
1. Choose the reference spot correctly
Do not compare with the old silicone joint – it is yellowed, dirty and usually considerably darker than when new. Take the mortar joint between the tiles as the reference, and at a clean spot not directly exposed to weathering.
2. Compare in daylight
Artificial light falsifies shades of grey massively – warm-white LED pulls them towards beige, cool-white towards bluish. The colour chart belongs at the window or outside in the shade. And place it directly on the joint, not next to it on the tile.
3. Shortlist two candidates
Usually two neighbouring tones remain between which the decision is hard. Take both – a second cartridge costs little compared with the effort of cutting a wrong joint out again.
4. Run a trial joint and let it dry
At a concealed spot – behind the toilet, under the bathtub apron, in a corner that will later be hidden by a cabinet – run a short joint and let it cure through completely. Only then assess it.
Wet looks different from dry
This is the point at which most wrong purchases arise. Freshly run silicone looks darker and richer because the surface still shines wet. After curing the tone lightens and becomes more matt – clearly so with light colours, by a noticeable shade with greys.
Anyone who decides after ten minutes decides on the wrong basis. Allow at least 24 hours, longer with thick joints and a cool environment.
The common colours at a glance
| Colour group | Typical tones | Where they are used |
|---|---|---|
| White | White, off-white, cream white, jasmine | Standard on sanitary fixtures, white tiles |
| Transparent | Colourless, crystal clear | Glass showers, when no tone matches |
| Light greys | Silver grey, manhattan, light grey | grey tiles, concrete look |
| Medium greys | Cement grey, concrete grey, basalt grey | the most frequent range at present |
| Dark tones | Anthracite, black, graphite | dark large formats, slate look |
| Beige and sand | Bahama beige, sand, pergamon, caramel | Natural stone look, warm tiles |
| Brown | Brown, medium brown, nut brown | Wood decor, terracotta |
In practice most sales fall on a handful of tones around white, manhattan, silver grey, cement grey, Bahama beige and anthracite. The remaining depth of the range covers the special cases – and that is exactly what it is there for.
Transparent: the emergency solution that is often the best
If no tone really matches, colourless silicone is often the cleverer choice than a shade of grey that is off by two nuances. Transparent recedes visually and lets the substrate show through.
Two restrictions: in wide joints transparent looks glassy and makes irregularities visible. And on strongly textured substrates it can appear milky. For narrow joints on glass and on multicoloured mosaics, on the other hand, it is often the cleanest solution.
White is not the same as white
Sanitary fixtures are seldom pure white. Ceramics from different manufacturers and from different decades differ noticeably – from cool white through off-white to pergamon. A pure white joint on an off-white bathtub stands out immediately.
So hold the colour chart directly against the fixture even with white, not only against the tile.
Practical points to think of beforehand
Coloured silicones are mixed in batches. Between two production batches there can be minimal deviations that become visible on a continuous joint. Work out the requirement once and buy with a reserve – from one delivery.
On marble, granite and other natural stones no normal sanitary silicone may be used – the plasticisers migrate into the stone and produce dark edges along the joint that no longer go away. A natural stone silicone belongs there; which one is explained in the comparison of Ottoseal S70 and S80.
The most beautiful colour is no use if the joint is wrongly dimensioned or smeared. On width, depth and joint-back adhesion everything is in the instructions on joint width and joint depth; for application in detail there are separate instructions.
A decision with consequences for everyday life: on anthracite and black, limescale edges are clearly visible, on white and beige, by contrast, every dark spot. How to get both under control is explained in the article on Cleaning silicone joints.
Colour stability over the years
Silicone changes over time, and the colour helps determine how noticeable that is.
White joints yellow, above all in rooms without daylight. That is not a defect but a property of the material: without the UV component in the light, ageing processes proceed differently than at the window. Windowless bathrooms are therefore particularly affected.
Dark joints bleach out when exposed to direct sun. At the window connection and on the south side that is visible after a few years.
Sanitary silicones with fungicidal additives hold back mould infestation for longer, but not indefinitely. The active ingredients are washed out over the years; at some point every wet-room joint is due. As a rule of thumb, a well-applied sanitary joint lasts five to ten years.
Reading colour charts correctly
A printed colour chart is an approximation, not proof. Printing inks can reproduce the appearance of a cured silicone only to a limited extent, and depending on print run and paper, two charts from the same manufacturer differ slightly from each other.
More reliable are sample strips made of real material, on which the colour is applied as cured silicone. Where they exist, they are to be preferred to any printed chart – they show not only the tone but also the degree of gloss.
Three things that apply to every colour chart:
Colour charts age. A chart that has lain on the shelf by the window for two years has faded. If it is visibly yellowed, it is no longer good as a reference.
The surrounding colour deceives. The same grey looks darker next to white and lighter next to anthracite. So place the chart directly on the joint, do not hold it next to it – and when comparing, cover the remaining fields with your hand.
The degree of gloss counts too. Two silicones in the same colour, one glossy, one matt, look different on the surface. Next to matt tiles and natural stone a glossy joint stands out, even if the tone is right.
Emphasising the joint or making it disappear
Beside the question "which tone suits" there is a design one: should the joint be invisible at all?
The disappearing joint is the normal case. Colour as close as possible to the grout, matt finish, clean narrow line. The result is calm and lets the tile surface work – the right choice in small bathrooms, where every additional line cuts up the room.
The emphasised joint is a deliberate decision, for example a dark joint with light tiles. It works if it is carried through consistently: then, however, in the whole room, in the same width and in the same colour as the mortar joints. A dark silicone joint at the bathtub with light mortar joints in the rest of the bathroom does not look intended but wrong.
What applies in both cases: one colour for the whole room. Nothing looks as untidy as three silicone joints in three shades because more was bought on three occasions.
Special cases
| Situation | Recommendation |
|---|---|
| Glass shower screen on tile | Transparent – any colour shows in the glass as a dark edge |
| Acrylic bathtub, white | Match the colour to the bathtub white, not to the tile |
| Stainless steel sink in worktop | light grey or transparent; white contrasts too harshly |
| Two tile colours meet | Tone of the continuous mortar joint, not of the tiles |
| Connection to varnished wood | Tone of the wood; a paintable sealant is also conceivable here |
| Dark large format, narrow joint | Anthracite instead of black – pure black acts as a harsh line |
If the joint is already in the wrong colour
Painting over is ruled out, applying a second layer over it as well: new silicone does not adhere reliably to cured silicone, and a second layer becomes thick and untidy. Only complete replacement remains.
The procedure in brief: cut through the old joint on both flanks with a joint knife or utility knife and pull it out in one piece. Then remove the silicone residue completely – with a plastic scraper, on delicate surfaces with silicone remover. Then clean the flanks with isopropanol and let them dry completely.
The critical point is the removal of residue. Remaining silicone haze prevents the new joint from adhering – and because the old colour is in it, it also shimmers through the new tone. Anyone who is sloppy here runs the joint again in two years.
Frequently asked questions
How do I find out what colour my silicone joint is?
Via the grout: look up the manufacturer and colour of the mortar joint and check it in the silicone manufacturer's assignment list. If the mortar is unknown, place the colour chart in daylight directly on a clean mortar joint – not on the old silicone joint, which is discoloured.
What colours are there for sanitary silicone?
The big ranges comprise well over a hundred tones: white and off-white, transparent, the complete grey series from silver grey to anthracite and black, beige and sand tones as well as browns. They are aligned to the colour charts of the common grouts.
Does the silicone joint have to be exactly the colour of the grout?
Not necessarily, but it should be close. The elastic joint and the mortar joint meet directly in the corners, where every deviation is in direct comparison. A deliberately contrasting joint is possible as a design choice – but then consistently in the whole room.
Why does my joint look different after drying?
Fresh silicone shines wet and therefore looks darker and richer. As it cures it lightens and becomes more matt. So assess the colour only after complete curing, at the earliest after 24 hours.
Can I paint over silicone to change the colour?
Not with classic silicone – paint does not adhere to it permanently and tears off the first time it stretches. Acrylic and certain hybrid sealants can be painted over, but in the sanitary area they do not offer the same resistance to water and mould.
Which silicone do I take for multicoloured mosaic tiles?
Usually transparent silicone or a tone that picks up the joint colour of the mosaic. Orienting yourself on a single tile colour almost always leads to a joint that matches one part of the picture and not the rest.
How many cartridges do I need?
Rule of thumb: joint width in mm × joint depth in mm gives the usage per linear metre in millilitres. With a joint 8 × 8 mm that is 64 ml per metre, so a 310 ml cartridge is enough for just under 5 metres. Add waste and a reserve.
Are there colour differences between two cartridges?
Not within one batch; between two production batches there can be minimal deviations. With continuous, clearly visible joints, therefore, obtain the whole quantity at once.
