Flexible Adhesive To Join Neoprene Tubes

What flexible adhesive will join neoprene tubes?

Selleys' answer starts with a caution: this type of tubing can be difficult to glue. The recommendation is conditional. If what you have is neoprene pipe insulation — neoprene foam — you might be able to use Selleys Multi Grip, listed on this site as Selleys Fix & Go Multi Grip.

The word "might" is doing real work there, and it is worth understanding why, because it changes what you should do next.

Foam insulation and solid tube are different problems

Neoprene foam pipe insulation is a closed-cell foam lagging, usually slit down one side. Joining it is a low-stress task: the sleeve is not carrying pressure, it is not being stretched, and the joint only has to close a seam and stay closed. A flexible general-purpose adhesive has a reasonable chance here, which is the case Selleys is describing.

Solid neoprene tubing — the rubber hose sense of the word — is a different matter. It is a synthetic rubber that stays flexible, resists solvents and oils, and has a low-energy surface that most adhesives struggle to wet properly. If the joint will carry fluid, hold pressure or be stretched, an adhesive butt joint is not a repair Selleys nominates a product for, and no Selleys technical data sheet publishes a figure for it. For a pressurised line, the correct answer is a mechanical connector — a barbed joiner and clamps — not glue.

So the first thing to establish is which of the two you have. If it is foam lagging, read on. If it is a hose that will hold anything, use a fitting.

What Multi Grip is

Selleys Fix & Go Multi Grip is a multi-purpose solvent adhesive for household, hobby and DIY applications. It is fast bonding, flexible and water resistant, and it dries clear. That combination — flexible and clear — is what makes it the candidate here: a rigid adhesive on a foam sleeve would simply crack along the seam the first time the pipe was flexed.

It bonds plastics, though not polyethylene or polypropylene, and there is no published technical data sheet for it, so there are no cure-time or strength figures to quote. Treat the guidance below as method rather than specification.

How to make the joint

1. Confirm the material. If the tube is a solid rubber hose that will carry fluid or pressure, stop and use a mechanical fitting.
2. Make sure the surfaces are clean and dry. Neoprene foam often carries a dusty or slightly waxy surface film from manufacture — wipe it off.
3. Test on an offcut first. This is not optional advice on a material Selleys describes as difficult to glue. Bond two scraps, let them cure fully, then flex and pull the joint. A bond that peels on the bench will peel on the pipe.
4. Apply a thin layer to one surface.
5. For a faster bond, apply the adhesive and leave the surfaces open for 1 minute before pressing them together.
6. For very porous surfaces — and open-cut foam is porous — seal the surface first by coating it with a thin layer of adhesive and allowing it to dry, then apply a second coat to form the bond as directed. On foam, this priming step makes a substantial difference, because the first coat is otherwise absorbed rather than forming a film.
7. Press the surfaces together and hold or lightly clamp them. Tape wound around the sleeve works well and does not crush the foam the way a clamp can.
8. Allow it to set undisturbed. Full cure takes several hours.

Limitations

• Not suitable for polyethylene or polypropylene. Some pipe lagging sold as generic "foam" is polyethylene, not neoprene, and looks very similar. If yours is PE foam, this product will not bond it.
• Not for polystyrene foam. It is a solvent adhesive and will attack expanded polystyrene.
• Not for underwater use or constant moisture. It is water resistant, which is not the same thing. Lagging on a condensing chilled-water line sits in constant moisture and is outside this.
• Use on clean, dry surfaces, and replace the cap immediately after use.
• Neoprene tubing is difficult to bond. Selleys does not guarantee an adhesive joint on it, and the recommendation above is explicitly conditional on the material being foam.

If Multi Grip is not right for your tube

Two alternatives are worth knowing about, both with their own constraints.

For a difficult plastic, Selleys directs you to All Plastics, a two-step primer and adhesive system that bonds plastics including polyethylene and polypropylene, which ordinary adhesives cannot.

For a flexible, weather- and impact-resistant bond on rubber, Fix & Go Shoe Repair is formulated to stick to rubber, leather, canvas, cork, EVA foam and most plastics, with a working time of 1 minute, initial bond at 24 hours and maximum bond at 72 hours. It is a shoe adhesive rather than a plumbing product, but the substrate list is relevant. It is not for polyethylene or polypropylene, and it may cause some vinyl and plastics to discolour or harden — test in a small hidden area first.

Safety: all three candidates are Class 3 flammable liquids

There is no low-hazard option among the products named above, and that is worth saying plainly rather than burying. Fix & Go Multi Grip, All Plastics and Fix & Go Shoe Repair all carry the signal word Danger on the same three classifications: H225, highly flammable liquid and vapour; H319, causes serious eye irritation; and H336, may cause drowsiness or dizziness. Shoe Repair is additionally classified as Dangerous Goods Class 3, UN 1133. Substituting one for another changes what the joint does, not what the fumes do. Ventilation is the control here, not product selection.

The problem is where pipe lagging lives. Insulation gets joined in subfloors, ceiling cavities, cupboards under sinks, plant rooms and laundries — small, enclosed, poorly ventilated spaces, and often the same spaces that contain a gas hot water unit with a standing pilot. H225 vapour is what ignites, it is heavier than air, and it travels, so an ignition source at floor level some distance away is still an ignition source. A subfloor is the worst case: the vapour cannot rise out of it.

The method above doubles the exposure, for good reasons. The priming step — a thin coat on the porous foam, left to dry, then a second coat — is the right technique, and it also means twice the solvent applied and a long period where it is evaporating rather than curing. Add the one-minute open time before pressing, and the total time with wet adhesive exposed is substantial. Cut the lengths and make the bond in the open air where you can, then fit the sleeve, rather than gluing in situ in a crawl space.

H336 is the classification people discount, and it is the wrong one to discount here. Solvent narcosis in a confined space is not just unpleasant; getting out of a subfloor or off a ladder while dizzy is the actual injury mechanism. If you start to feel light-headed, that is the signal to come out, not to finish the join. And because much of this work is overhead — lagging on ceiling pipes — H319 stops being theoretical: gravity puts the adhesive on your face. Wear eye protection for anything above shoulder height.

The genuinely lower-hazard route is the one the page already recommends for solid tube: a barbed joiner and clamps carries no chemical hazard at all.

Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions about gluing neoprene

Is neoprene hard to glue?

Yes. Selleys describes this type of tubing as difficult to glue, and its recommendation is conditional on the material being neoprene foam rather than solid tube.

What does Selleys recommend?

For neoprene pipe insulation — neoprene foam — you might be able to use Selleys Multi Grip.

Can I join a pressurised hose with adhesive?

Selleys does not nominate a product for that, and no Selleys data sheet publishes a figure for it. Use a mechanical connector.

Should I test first?

Yes. On a material described as difficult to bond, test on an offcut and let it cure fully before you rely on the joint.

What if my lagging is polyethylene foam?

Multi Grip is not suitable for polyethylene or polypropylene. Selleys directs difficult plastics to All Plastics.

Will the adhesive stay flexible?

Multi Grip is described as flexible and water resistant, and dries clear — which is why it is the candidate for a joint that has to bend.

How do I glue a porous cut foam face?

Seal it first with a thin coat of adhesive, let it dry, then apply a second coat to form the bond.

How long do I hold it?

Press the surfaces together and allow to set undisturbed; full cure takes several hours. There is no published technical data sheet for this product, so allow generously.

Is it waterproof?

It is water resistant but not for underwater use or constant moisture.