What is Selleys 3 in 1 Adhesive, Sealant & Gap Filler, and where should you use it?

Selleys 3 in 1 is a moisture curing silyl-modified polymer (SMP) that does three jobs from one cartridge: it is a high strength construction adhesive, a waterproof sealant and a no-shrink gap filler. It works on glass, metal, timber, brick, concrete, tiles and most plastics, interior or exterior, and — unusually for a sealant — it can be applied to wet or dry surfaces.

The single most useful thing to know before choosing it is that its versatility comes from the SMP chemistry, and that chemistry sets one hard rule about finishing: it cannot be painted with solvent-based paints. Water-based paint only. If you have already planned an enamel topcoat over the joint, this is not the product for that job.

Technical specification

Property	Typical result
Technology	Moisture curing silyl-modified polymer (SMP)
Colour	White
Density	~1.65
Application temperature	5 to 30°C
Tooling time (23°C, 50% R.H.)	~15 minutes
Skin time (23°C, 50% R.H.)	15 to 30 minutes
Cure rate (23°C, 50% R.H.)	3 to 4mm per 24 hours
Slump	0mm
Tensile strength (DIN 53504)	1.3MPa
Shore A hardness	40 ± 5
Elongation at break (DIN 53504)	>250%
Modulus at 100% elongation (DIN 53504)	~0.8MPa
Movement capability (ISO 9046 modified)	±20%
Service temperature	0 to 70°C
VOC content (theoretical calculation)	~34g/L

Supplied as a 480 gram cartridge in white. These are indicative data only, not intended for the preparation of specifications.

What the key numbers mean in practice

Cure rate of 3 to 4mm per 24 hours. This is a moisture-curing product, so it cures inward from the exposed surface at roughly 3–4mm each day. A shallow 4mm bead in a tile joint is through-cured in about a day; a deep gap filled in one pass will take proportionally longer, and the inside of that bead is still soft while the outside feels firm. Where you have filled real depth, wait longer before subjecting the joint to movement or load.

Tooling time ~15 minutes, skin time 15 to 30 minutes. These two numbers together define your finishing window. You have about a quarter of an hour to force the bead into the joint and tool it smooth. Once the surface starts skinning, tooling drags and tears the bead rather than smoothing it, and the only remedy is to cut it out and start again. Work in short runs rather than laying a whole room's worth of bead before you pick up the spatula.

Slump 0mm. The bead does not sag once applied, which is what makes vertical and overhead joints practical — you can run a bead up a wall junction and it will stay where you put it.

Movement capability ±20%. The cured bead tolerates the joint widening or narrowing by a fifth of its width without failing. That covers normal thermal movement in most domestic joints, provided the sealant has genuine depth in the joint rather than being smeared thinly across the surface.

Application temperature 5 to 30°C, service temperature 0 to 70°C. The first is the range you can apply it in; the second is what the cured bead will live with. Applying below 5°C on a cold winter morning is outside the stated range.

Where to use it

Selleys lists 3 in 1 for:

• Sealing, bonding and filling
• Wet or dry surfaces
• Interior and exterior use
• Glass, metal, timber, brick, concrete, tiles and most plastics

The technical features Selleys claims for it are a high strength bond, water and weather resistance, excellent adhesion, high durability, versatility, interior and exterior use, paintability, non-cracking, UV resistance, mould resistance, fast grab and low VOC.

How to apply it

Start the same way for all three jobs: cut the tip and attach the nozzle, insert the cartridge into a caulking gun, then cut the nozzle to the size you need. Size the opening to the joint — you can always widen the cut, but you cannot make it smaller again. Surfaces must be clean, dry and free from dust, grease, and old or crumbling sealant.

Using it as an adhesive

1. Apply to one surface — in beads for broad surfaces, spaced every 30cm, or in dots for small surfaces.
2. Press the surfaces together.
3. Allow it to cure. Larger, heavier items need to be supported until the adhesive cures.

Using it as a sealant

1. Apply the product, making sure it is forced into the joint with good contact to both surfaces.
2. Tool with a soap solution before skinning occurs.

Using it as a gap filler

1. Apply the product into the gap.
2. Smooth off with a spatula dipped in soapy water.
3. Allow it to skin before painting with water-based paints.

For neater joints, mask both sides before applying and remove the tape before the sealant skins. Tape pulled off after skinning drags the edge of the bead with it.

Limitations — where 3 in 1 should not be used

• It cannot be painted with solvent-based paints. If paint is required, paint with a water-based paint first. Selleys adds that a minimum of two coats are necessary to ensure the paint wets out the sealant surface properly.
• Not for polyethylene, polypropylene or Teflon. These plastics will not hold a bond.
• Not suitable for continuous water immersion. It is a waterproof sealant, not an underwater one.

If your job falls into one of these, the answer is a different product rather than this one applied more carefully.

Clean up and storage

Uncured product may be removed with mineral turps — which is why cleaning squeeze-out before the bead skins is worth the minute it takes. Cured product has to be removed by scraping or sanding, or with the help of a sealant remover.

Store in cool, dry conditions below 30°C, and use within 6 months of opening. Because this is a moisture-curing product, an opened cartridge left on a shelf will slowly cure in the nozzle; that six-month figure is a real limit, not a formality.

Hazard classification

Selleys 3 in 1 White is not classified as hazardous under the criteria of Safe Work Australia GHS 7, and it is not classified as Dangerous Goods by the Australian Code for the Transport of Dangerous Goods by Road & Rail or by New Zealand NZS5433. It carries no signal word and no hazard statements.

That is a definitive finding from the product's own safety data sheet rather than missing information, and for a product that does the work of a construction adhesive it is genuinely unusual. Most high-strength construction adhesives in this range are solvent-borne and arrive with a flammability classification and a list of hazard statements attached. This one does not, and the ~34 g/L VOC figure quoted in the specification above is the same fact expressed a different way: there is very little volatile solvent in the cartridge to evaporate, so there is very little to breathe and nothing to catch alight.

That has a practical consequence worth naming. The jobs this product is sold for — bonding and sealing indoors, in bathrooms, in cupboards, along wall junctions — are exactly the confined, poorly ventilated spaces where a solvent-borne adhesive makes you open a window and take breaks. Here natural ventilation is adequate under normal use. It is still worth working in a ventilated space, but the reason is comfort rather than exposure.

Ordinary precautions still apply. Wear safety glasses and nitrile gloves if you are tooling a bead by hand, wash your hands afterwards, and keep the product away from food. Store it below 30 °C in a cool, dry place out of direct sunlight, with the container upright and closed — which is also what protects the six-month opened shelf life noted above, since this is a moisture-curing product and the air is what starts the clock. If uncured product gets in an eye, wash it out with water immediately, and seek medical advice as a precaution.

One thing the classification does not cover: cured product has to be removed by scraping or sanding. Not classified as hazardous is a statement about the material as supplied, and sanding any cured polymer produces dust worth keeping out of your lungs and eyes.

Common questions about Selleys 3 in 1

Can I paint over it?

Yes, but only with water-based paint. It cannot be painted with solvent-based paints. Allow the product to skin before painting, and use a minimum of two coats so the paint wets out the sealant surface properly.

How long before it is fully cured?

The cure rate is 3 to 4mm per 24 hours at 23°C and 50% relative humidity, so it depends on how deep the bead is. A thin bead cures in about a day; a deep fill takes proportionally longer.

How long do I have to smooth the bead?

Tooling time is about 15 minutes, and the surface skins at 15 to 30 minutes. Tool with a soap solution before skinning starts.

Can I apply it to a damp surface?

Yes. Selleys lists it as suitable for wet or dry surfaces. The surface still needs to be clean and free from dust, grease and old crumbling sealant.

Will it work underwater or in a pond?

No. It is not suitable for continuous water immersion.

Will it stick to plastic?

It works on most plastics, but not polyethylene, polypropylene or Teflon.

Will it sag if I run a bead up a wall?

Slump is 0mm, so the bead holds its shape on vertical joints.

How much movement will the joint take?

Movement capability is ±20% under ISO 9046 modified — the joint can widen or narrow by a fifth of its width without the bead failing.

What temperature can I apply it at?

Application temperature is 5 to 30°C. The cured product has a service temperature of 0 to 70°C.

What size does it come in?

A 480 gram cartridge, in white.

How do I remove it once cured?

Scrape or sand it off, or use a silicone remover to help. Uncured product comes off with mineral turps.

How long does an opened cartridge last?

Use it within 6 months of opening, stored in cool, dry conditions below 30°C.

Can I use it to hang something heavy?

It is a high strength construction adhesive, but larger and heavier items need to be supported until the adhesive cures — do not rely on initial grab to hold weight.

For the rest of the range, see other glues and the broader glues and adhesives category.