The gun comprises a cradle that holds the cartridge in position, and a plunger that pushes the base of the cartridge forwards, forcing the sealant or adhesive through the nozzle.
This allows the adhesive to be delivered in a steady and controlled manner to create an even bead.
Most caulking guns are manual, with the plunger controlled by the lever action of the trigger.
Cordless caulking guns have an electrical-powered plunger that is activated by the trigger, resulting in an even flow and less fatigue.
TIP Keep the screw-on cap for the cartridge nozzle so unused compound can be stored without hardening.
1. Push the nozzle forwards
Position the nozzle at a 45º angle at the start of the gap, then gently squeeze the trigger while moving the nozzle forwards to fill the gap, keeping an even pressure on the trigger.
Pushing the nozzle as you work forces the sealant into the gap so it adheres to both surfaces and creates a neat result.
2. Meet in the middle
Long gaps can be tricky if they require more sealant than the gun can deliver in one run, as restarting where you finished the first run can create an uneven blob.
Instead, start at one end, then start at the other end and meet in the middle, keeping the midpoint away from eye level so you can’t see the join.
3. Smooth the bead
To smooth uneven beads, use a finger dipped in soapy water or a smoothing tool with rounded edges and drag it along the bead.
When using silicone, apply masking tape 5mm from either side of the gap before applying the silicone. Smooth the bead and remove the tape before the silicone cures.