How to run a neat bead of sealant

Learn to run a smooth, even bead of sealant without gaps, smears or wobbles.

SB-01Clean and dry the jointA joint is the gap between two surfaces, like where a bath meets a tiled wall. Wipe out old sealant, dust and grease with a damp cloth, then dry it fully. Sealant will not stick to a dirty or damp surface, so this step decides whether your work lasts.

SB-02Cut the nozzle to the right sizeThe nozzle is the plastic tip on the sealant tube. Snip the very end off at a 45 degree angle with a sharp knife or scissors, cutting only a small amount off first. The hole should be roughly the same width as your gap; too big and you will waste sealant and make a mess, too small and it will not flow.

SB-03Mask either side of the gapStick a strip of masking tape along each side of the joint, leaving a small gap between the two strips exactly where you want the sealant line to sit. This is optional for confident hands, but for a first attempt it is the single biggest help for a straight, neat edge.

1 roll · Masking tape

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SB-04Load the sealant gunA sealant gun is the trigger-operated frame that holds the tube and pushes the sealant out. Drop the cut tube in nozzle-first, then squeeze the trigger a few times until you feel resistance and see sealant just reach the tip. Doing this before you start stops the first few centimetres coming out in a stuttering, uneven blob.

1 each · Sealant cartridge

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SB-05Run the bead in one steady passHold the gun at a consistent 45 degree angle to the joint and squeeze the trigger gently and evenly as you move along, rather than in bursts. Move at a slow, steady walking pace, not stopping halfway if you can help it. The beginner mistake is squeezing too hard and moving too fast, which leaves a thin, patchy line with gaps.

SB-06Smooth the bead while it is wetDip a finger, or a proper sealant smoothing tool, in water with a drop of washing-up liquid, then run it along the bead in one continuous stroke. This presses the sealant into the joint and gives it a neat, slightly concave shape. Do this within a minute or two, before the surface starts to skin over.

SB-07Peel off the masking tape immediatelyWhile the sealant is still wet, pull each strip of tape away slowly at a shallow angle, working along the joint. If you wait until the sealant has started to skin, the tape will drag it and ruin the clean edge.

SB-08Check the finished beadA good bead is a continuous, even line with no gaps, no smears on either side, and a slightly rounded or slightly hollow surface depending on how you tooled it. Run a finger lightly along it once it is touch-dry; it should feel firmly stuck to both surfaces, not loose or hollow underneath. Leave it fully untouched for the curing time stated on the cartridge, usually 24 hours, before it gets wet.

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