Short answer
Pereseal AF, N and 802 go tack-free in about 15 minutes and cure about 10 mm deep in 7 days. Our acrylics, 702 and FR, skin in 20–25 minutes and must be kept away from water for 24 hours. A bead that feels dry on top can still be soft in the middle.
When people ask how long sealant takes to dry, they usually mean something more practical. When can I shower? When can I paint? When can the joint take movement? The answer depends on the sealant, the size of the bead and the air around it.
Skin, tack-free and full cure
Sealant cures in stages. It helps to know which one you're waiting for.
- Skin time: a film forms on the surface. Tool the bead before this, and leave it alone afterwards.
- Tack-free time: the surface is no longer sticky. Dust won't stick to it and a light touch won't mark it.
- Full cure: the whole bead has cured through. Only now does it have its full flexibility and strength.
Silicone cures by drawing moisture from the air, so it cures from the outside in. The surface is finished long before the centre. Acrylic dries as its water evaporates, which also works from the surface inwards.
Cure times for the Pereseal range
- Pereseal AF, Pereseal N and Pereseal 802: tack-free in about 15 minutes, cures about 10 mm deep in 7 days. Tool within 5 minutes.
- Pereseal MP: skins in about 7 minutes, cures about 1.5 mm every 24 hours.
- Pereseal 702: skins in about 20 minutes. Keep it away from water for 24 hours.
- Pereseal FR: skins in about 25 minutes, tack-free within an hour. Keep it away from water for 24 hours.
These are typical figures at normal conditions. Dry air slows silicone down. Singapore's humidity helps, but a bead in a cold, dry air-conditioned room will take longer than the same bead outdoors.
Why a thick bead takes longer
Because silicone cures inwards, depth matters more than width. At about 10 mm a week, a 6 mm bead cures through in a few days. A 20 mm plug stuffed into an open cavity can stay soft in the middle for weeks.
That's one reason we use backer rod. It holds the bead at the right depth, so the sealant cures properly and still has room to stretch. Sealant trapped between two non-porous surfaces, such as behind a panel, gets little air and cures slowly too.
When you can use the joint
Water
Acrylics need 24 hours before water. For bathroom silicone, we tell customers to keep the shower off for at least 24 hours, and longer for a deep bead or a cold, dry room.
Paint
Only the acrylics take paint: 702 and FR. Let the bead dry through before painting, not just skin. Painting too early is the most common reason paint cracks over a joint; see can you paint over sealant. Don't paint silicone. The AF and N data sheets both exclude paint coatings.
Movement and load
A joint that has to move, or a part being held in place by sealant, needs the full cure. Support anything heavy until then.
If it stays soft
A bead that is still soft or sticky well past these times usually has one of four causes: it's too deep, the cartridge was past its shelf life, it went over contamination such as old silicone or soap, or the air was very dry. See how to store sealant for checking an old cartridge.
Don't paint over it or seal on top of it. Cut it out, clean the joint and do it again. If a whole run won't cure, keep the cartridge and tell us the batch number.
Working to a deadline?
Tell us the sealant, the joint size and when it has to be back in use. We'll tell you whether the timing works.
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