The tack-free time tells you how quickly the fresh caulk s outer surface will dry, or skin over. Once the caulk has skinned over, it will not pick up dirt and dust, and in most cases can be painted. Consult the cartridge label, though, before painting over the caulk. Some products such as silicone cannot be painted. The total cure time indicates the time required for the caulk to become completely stable, or reach the point where no further drying or shrinking will occur.
Most caulk poses no known health hazards after they are fully cured.
However, most caulks give off solvent fumes while they are curing, so adequate ventilation is needed for indoor caulking projects. As Table A indicates, some high-performance caulking compounds contain irritating or potentially toxic ingredients, and should therefore only be used outdoors. Never use lead-based caulking compounds, as they are highly toxic. Many states have already banned their use. Carefully read the manufacturer s instructions and take the appropriate precautions to ensure that pets and small children do not come into contact with the fresh caulk.