Moisture-curing sealants start curing at the surface first, typically forming a skin in about 10 to 60 minutes depending on chemistry, temperature and humidity. Tooling must be done before the skin forms, or the bead tears, wrinkles and loses contact with the joint faces. Tack-free time, a little later, is when dust no longer sticks. Hot, humid days shorten both.
Skin time on this silicone is ten minutes in this sun, so gun a short run and tool it right behind.
On hot afternoons crews gun shorter runs so the tool man stays inside the skin time.
Also heard as
- skinning time
- tooling time
Related terms
Tooling
Pressing and shaping freshly applied sealant with a tool to force it against the joint faces and give it a neat profile.
Dry tooling
Tooling sealant without water, soap or solvent on the tool, as most manufacturers require.
Silicone
A sealant with a silicon-oxygen backbone, prized for UV resistance and high movement capability.
Sausage
A soft foil or film tube of sealant loaded into a barrel gun, used instead of rigid cartridges on big jobs.