The drying time of bathroom silicone has to be the most common query i get from clients. And it’s understandable. Naturally they just want to know how long they have to leave their bath or shower before using it again.
As a rule of thumb, i always advise to leave the area for at least 24 hours, depending on the size of the silicone bead. A thicker silicone bead of more than around 4mm in depth will always take a little longer to fully cure.
Silicone is a deceptive material. It can feel touch dry within minutes, however this does not mean the sealant has fully cured.
Drying and curing are 2 different things, and this can be confusing. Let’s take a look at the difference.
Drying refers to the fairly rapid process of moisture evaporation from the surface of the silicone. When this happens, the sealant “skins” over and can feel almost dry to the touch.
Curing refers to the slower chemical reactions that take place under the surface once the sealant is exposed to oxygen. It usually takes anywhere between 1 to 5 days for sealant to be fully cured.
Baths & showers should only be used once the sealant has cured fully. Excessive moisture and rapid changes in humidity during the curing process can compromise the strength and flexibility of the sealant.
Factors That Can Affect Overall Curing Time
Size and thickness of the sealant bead
The thicker the sealant bead, the longer it takes to fully cure. A regular sealant bead of around 4mm will usually take around 24 hours to cure in regular conditions. Whilst thicker beads can take up to a week or even more depending on the size.
Please note, if the sealant is applied too thick (for example over an inch in thickness), i’m afraid it will probably never fully cure. The silicone just can’t obtain enough oxygen to create the chemical reaction required to cure the sealant.
Type of sealant
Some sealants take longer to cure than others. Different brands use slightly different chemical formulas when manufacturing their silicone.
Some bathroom sealants release different chemicals during the curing process, and as such are used for slightly different purposes.
For example, acetoxy curing silicone (Dowsil 785, No Nonsense Sanitary Sealant, Mapei AC), releases acetic acid when curing. This gives off a strong vinegar like smell and can be harmful to materials like metal and natural stone.
Neutral cure sealant (Dowsil 785N, Ardex ST) on the other hand releases alcohol during curing. It has a less offensive odour and is more suitable for sensitive substrates.
Acetoxy curing sealant always tends to cure faster than neutral cure silicone.
For more information on acetoxy and neutral cure silicone see out blog post "What's The Difference Between Acetoxy and Neutral Cure Silicone Sealant?"
Room temperature & humidity
Humid climates and warm room temperatures tend to facilitate a faster curing time than cold dry rooms. However, a hot room may cause the silicone to bubble, so try not to have the radiator on full blast when applying new silicone.
If you are looking for product recommendations or more information on which sealant to use for your bathroom, take a look at our blog post "The Best Silicone Sealant For Showers - Ultimate Guide".
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