When do you need a specialist adhesive rather than a multipurpose one?

Many adhesives are multipurpose, suitable for a variety of projects and materials. A specialist adhesive earns its place when you have a unique repair, or when you are working with materials that other adhesives do not support. That is the whole test: if a general-purpose glue names your material, use it; if it does not, this is the category to look in.

The two situations that most often send people here are water and flexibility — a bond that will be wet, or a bond in something that bends. Both defeat ordinary adhesives, and both have a purpose-built product in this range.

How to choose

If the repair will be wet, or underwater

When you are working with fibreglass and materials that will be exposed to water more frequently, Selleys points to Selleys Fibreglass Fix Repair Kit and MarineFlex. MarineFlex was developed to be applied above or below water and will cure under water — which is the property that distinguishes it, since most adhesives need a dry surface to bond to at all. Its product description covers sealing and bonding above and below the waterline, for protecting a boat from water damage.

If the material is plastic

Selleys All Plastics is the product for an extra strong bond on plastic surfaces, for DIY and industrial use. Plastics are the classic case where a general adhesive simply does not grip, so reaching for the specialist product first saves a failed repair.

If it is footwear

When you are not ready to give up your favourite pair of shoes, Selleys Shoe Fix is strong and flexible and works on leather, fabric, canvas, rubber and other footwear materials. It is described as setting in 24 hours — so plan the repair for a day you are not wearing them. Selleys Fix & Go Shoe Repair is the other footwear option, for repairing and reinforcing soles, heels and leather.

If the surface is glass, mirror, metal or stone

Two products outside this category do specialist work that people often come here looking for. Other Liquid Nails adhesives can be used on glass, but Selleys Liquid Nails Mirror, Metal and Glass offers higher heat, UV and steam resistance — which makes it suited to fixing house numbers to exterior walls, or mounting bathroom fixtures where steam is constant. Selleys Liquid Nails Landscape is the better choice for pavers, stones, and even stabilising stone steps.

The products in this category

• All Plastics — extra strong bond for all plastic surfaces, for DIY and industrial use.
• Marine Flex — sealing and bonding above and below the waterline; developed to be applied above or below water and to cure under water.
• Shoe Fix — strong, flexible footwear adhesive for leather, fabric, canvas, rubber and other footwear materials; sets in 24 hours.
• Fix & Go Shoe Repair — for repairing and reinforcing soles, heels and leather.

Selleys Fibreglass Fix Repair Kit is named in this category's own text for fibreglass work, but does not have a published product page in the current catalogue.

The safety divide in this category — three solvent products and one that is not

Four products, and on hazard they split three to one. It is the sharpest divide in the adhesives range, and it does not follow the job — it follows whether the product carries a solvent.

Group	Products	Classification
Danger — highly flammable solvent	Shoe Fix, Fix & Go Shoe Repair, All Plastics	H225 highly flammable liquid and vapour; H319 causes serious eye irritation; H336 may cause drowsiness or dizziness. The two shoe adhesives are also Dangerous Goods Class 3, UN 1133 by road, sea and air; Shoe Fix is additionally Packing Group II and a Schedule 5 Poison
Warning — one classification	Marine Flex	Eye irritation Category 2A, and nothing else. No flammability classification, no narcotic-effect classification, and not Dangerous Goods for transport

Marine Flex is the mildest product in this part of the range by a wide margin, and that follows from its chemistry rather than from a softer formulation of the same idea. It is a Sil-X hybrid polymer that cures with atmospheric moisture, so there is no solvent to evaporate, no flammable vapour, and no sensitisation classification. If the deciding factor is an enclosed space, a boat cabin, a household with children, or work near any ignition source, it is the only product here without a flammability classification attached.

The three solvent products share a mechanism, and every one of their classifications comes out of it. These adhesives work by evaporation, so the step the instructions call letting the film go tacky is the same event as the vapour entering the room. That matters most for the shoe repairs, which invite the worst posture for it — indoors at a table, face a foot above an evaporating film, for as long as it takes to work along a sole. Feeling light-headed is the classified H336 effect, not fatigue. And H225 applies even though nothing is heated: an acetone-dominant blend is flammable above an open tube on an ordinary day, and the clean-up solvent is the same chemistry, so the rag is flammable too.

All Plastics is the one whose hazard sits in the part people treat as preliminary. Its classifications belong to the primer, over 60% isopropanol; the adhesive itself is a cyanoacrylate, which bonds skin instantly and reacts strongly with cotton and wool. This is a bench-repair product, so the hazard to think about is a soldering iron or heat gun on the same bench while the primer flashes off.

Comparing the four on the numbers that decide the repair

These products run on completely different timescales, and the spread is the opposite of what most people expect. Shoe Fix publishes no technical specification table; its two published timing statements are shown, and where nothing is published the cell says so.

Product	Working or set time	Initial bond	Full strength	Pack
All Plastics	Sets in 30 seconds	30 minutes	24 hours	3mL tube with primer
Fix & Go Shoe Repair	Working time 1 minute	24 hours	72 hours	50mL tube
Shoe Fix	See product page	Sets in 24 hours	Maximum strength over several days	See product page
Marine Flex	Skin formation approx. 40 minutes	See product page	Cures approx. 2mm per 24 hours	410g cartridge, white or black

A small repair is not a quick repair here, and that catches people out. All Plastics sets in thirty seconds and is at maximum strength in a day. The two shoe adhesives take a full day to reach initial bond and another one to three days to reach full strength. The failure reported with shoe repairs is almost always the same: a joint loaded hard while it was still building strength, which peels at the toe or the heel and then never re-bonds as well the second time. Plan the repair for a day you are not wearing them, and if the footwear takes a beating, the extra days before hard wear cost nothing and materially change the result.

The two shoe adhesives carry identical hazard classifications, so choosing between them is not a safety question — it is a question of what the solvent does to the shoe. Fix & Go Shoe Repair is built on acetone with acetate esters. Shoe Fix is acetone with petroleum naphtha and methyl ethyl ketone, and that blend is the sourced reason for its own warning that it may affect some plastics and vinyls. Modern footwear is largely synthetic — EVA midsoles, TPU cages, coated uppers — so on anything other than leather and rubber, test on a hidden area before committing to a visible seam.

All Plastics only reaches its published strengths if you use the primer. The 2.9 MPa on polypropylene and 5.6 MPa on polyethylene are quoted in tensile shear at 24 hours with the primer pen applied to both sides of the substrate. Polyethylene and polypropylene are the plastics that bond to almost nothing, and the primer is what makes the surface accept the adhesive at all — skipping it is not a shortcut with a strength penalty, it is the difference between the repair working and not working. It is also where the flammability sits, so the primer step is the one that needs the window open.

Marine Flex behaves in the opposite direction to every intuition about drying. Selleys qualifies its 40-minute skin and 2mm-per-day cure figures with a warning that both run slower in the cold and faster in wet conditions or submersion — water accelerates this chemistry rather than spoiling it, which is what lets it be applied and cured under water. The practical consequence is the depth of the fillet: at roughly 2mm per 24 hours, a deep bead on a hull is a multi-day job, not an afternoon one, and a boat relaunched on the strength of a firm-feeling surface is resting on a bead that is still soft at the back. Note too that it is a stiff sealant by marine standards — Shore A 75, elongation up to 30% — so it is a bonding and sealing product for joints that hold position, not a high-movement expansion joint sealant.

Common questions about Selleys specialist adhesives

When should I use a specialist adhesive instead of a multipurpose one?

When the repair is unique, or the material is not supported by the multipurpose adhesives. If your material is not named on a general-purpose product's page, that is your answer.

Which adhesive works underwater?

MarineFlex. It was developed to be applied above or below water and will cure under water.

What should I use on fibreglass?

Selleys names the Fibreglass Fix Repair Kit and MarineFlex for fibreglass and for materials exposed to water more frequently.

Which glue works on plastic?

Selleys All Plastics, described as giving an extra strong bond on all plastic surfaces.

What is the difference between Shoe Fix and Fix & Go Shoe Repair?

Both are footwear adhesives. Shoe Fix is described as strong and flexible across leather, fabric, canvas, rubber and other footwear materials, and sets in 24 hours. Fix & Go Shoe Repair is described for repairing and reinforcing soles, heels and leather.

How long do I have to wait before wearing repaired shoes?

Shoe Fix is described as setting in 24 hours.

What should I use to fix house numbers to an exterior wall?

Liquid Nails Mirror, Metal and Glass, which offers higher heat, UV and steam resistance than the other Liquid Nails adhesives, and which Selleys names for exactly this job.

What holds pavers and stone steps?

Liquid Nails Landscape, described as better suited to pavers, stones and stabilising stone steps.

Is there a specialist adhesive for bathroom fixtures?

Liquid Nails Mirror, Metal and Glass is named for mounting bathroom fixtures, on the strength of its steam resistance.