What is Selleys Knead It Steel, and where should you use it?

Selleys Knead It Steel is a hand kneadable, fast setting, non-rusting co-extruded epoxy repair system intended for metal items. It is supplied with a black hardener inside a grey resin, so the mixing indicator is built in: you knead until the two colours disappear into one, and the cured repair dries dark grey.

The single most useful thing to know before you use it is how to tell it is mixed. Uniform colour is one signal. The other is heat — Knead It becomes warm as it is kneaded, and feeling that mild warmth radiating from the putty tells you the reaction has started. If it is still streaky and still cold, keep working it.

What the key numbers mean in practice

• 3–5 minutes at 25°C — the working time. Cut off only what you can place and shape in that window.
• Allow 60 minutes before handling — the point at which the repair can be touched without deforming it.
• Full cure in 24 hours at 25°C — the point at which machining, drilling and painting belong.
• Application temperature 5–40°C — the ambient conditions Selleys nominates for applying it.
• Service temperature −40°C to +120°C continuous, intermittent to +140°C — where the cured repair can live.

Those two temperature figures do different jobs. The application range describes the day you are working in; the service range describes the finished repair's environment. Continuous means sustained exposure, which is the number to design around. Intermittent to +140°C describes short excursions, not a normal running temperature.

The 60 minute and 24 hour milestones are also distinct. At an hour the repair is stable enough to handle. At 24 hours it has reached its final state, and that is when it is fair to drill, tap or machine it.

Where to use it

Knead It Steel is aimed at metal repair. Selleys lists it for:

• Repairing small engine parts, radiators and petrol tanks
• Sealing leaks and filling cracks in iron pipes, tanks and gutters

The stated substrate list is broad: steel, ferrous metals, aluminium, other metals, glass, concrete, timber and most plastics. Read "most plastics" as the qualified statement it is — it is not a claim that it bonds to every plastic, and on an unfamiliar plastic a small test is cheaper than a failed repair.

Its non-rusting formulation is the reason it suits gutters, tanks and pipework. A repair that itself corrodes in a wet steel fitting has only postponed the problem.

If your job is not metal-focused, the rest of the range on the specialist fillers and putty page covers the alternatives: Knead It Multipurpose for general repairs, Knead It Aqua for wet and underwater repairs, and Knead It Autofix for vehicle work.

How to apply it

1. Make sure the surface is clean and dry. On a leaking pipe or tank this means the repair area is dry at the time of application, not merely dry-ish.
2. Cut off the required amount and knead until the colour is uniform. The black hardener disappearing into the grey resin is your mixing gauge, and the mild warmth you can feel confirms the reaction has begun.
3. Apply within the working time — 3–5 minutes at 25°C. Press it firmly into the crack, hole or worn area.
4. Allow 60 minutes before handling.
5. Allow 24 hours for full cure before machining, drilling, sawing, sanding, filing or painting.

Shape the putty as closely as you can while it is soft. Every minute spent getting the profile right by hand is several minutes of filing saved once it has gone hard.

Machining and finishing

Once cured, Knead It Steel can be machined, drilled, sawed, sanded, filed and painted. That range of operations is what makes it useful for engineering repairs rather than only for filling: you can build up a worn feature and then bring it back to size with ordinary tools.

The cured colour is dark grey. If the repair is going to be visible and colour matters, plan on painting it — and do that after the full 24 hour cure.

Working conditions

Apply between 5°C and 40°C. As with any two-part epoxy, temperature moves the timings in both directions: warmth shortens the working time, cold lengthens the set. In cold conditions give the repair longer before handling rather than testing it early and marking it.

Hazard classification

Classified as hazardous under Safe Work Australia GHS 7, with the signal word Warning.

• Sensitisation — Skin — Category 1A. H317: may cause an allergic skin reaction.
• Skin corrosion/irritation — Category 2. H315: causes skin irritation.
• Eye damage/irritation — Category 2A. H319: causes serious eye irritation.

It is not classified as Dangerous Goods for transport by road, rail, sea or air. No composition breakdown specific to this product is published in the material available here, so none is reproduced.

Category 1A is the sub-category used where there is strong evidence that a substance sensitises humans — a step more definite than a plain Category 1, and the most serious thing on this product. Sensitisation is not irritation. Irritation is local and reversible; sensitisation is the immune system learning to react, it is generally permanent once acquired, and afterwards a far smaller exposure will set it off. It is built up by repeated casual contact rather than by one dramatic incident.

Which is exactly the risk with a putty you are told to knead until the black hardener disappears into the grey resin. Mixing it properly by hand is the whole technique, and doing that bare-fingered job after job is the classic route to epoxy sensitisation. Knead it inside disposable nitrile gloves — you can still see the colour change and feel the mild warmth the directions above describe.

The second exposure window is the one the page calls machining and finishing. Once cured, this putty gets drilled, sawn, filed and sanded, and metal-repair work of that kind is done close to the face. Wear eye protection and a dust mask for it, and do not clear swarf and dust by blowing on it.

Protection

• Gloves — nitrile rubber; the SDS suggests these as suitable for intermittent contact, with the user making the final assessment.
• Eye protection — eye/face protection while kneading and applying, and safety glasses while machining, drilling, filing or sanding the cured repair.
• Ventilation — general ventilation at the bench, local exhaust where the product is used in quantity, and respiratory protection if that is not enough.
• Avoid inhaling vapour, mist or aerosols. Wash hands before eating, drinking or smoking, and wash contaminated clothing before reuse.

First aid

Exposure	What to do
Eyes	Hold the eyelids apart and flush the eyes continuously with running water. Keep flushing for at least 15 minutes, or until advised to stop by a doctor or the Poisons Information Centre, then go to a doctor or hospital.
Skin	Effects may be delayed. Remove contaminated clothing immediately and flush the skin and hair with running water for at least 15 minutes. If a rash, swelling, redness or itching develops, including hours later, seek medical assistance.
Inhalation	Move the person to fresh air, keep them warm and at rest until recovered. Seek medical advice if effects persist.
Swallowed	Rinse the mouth with water. Do not induce vomiting. Give a glass of water to drink and seek medical advice. Never give anything by mouth to an unconscious person.

If poisoning occurs, contact a doctor or the Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand — with the container to hand. Selleys emergency line: 1800 220 770 in Australia, 0800 220 770 in New Zealand.

Common questions about Selleys Knead It Steel

How do I know it is properly mixed?

Two signs. The colour becomes uniform — the black hardener no longer shows as streaks in the grey resin — and the putty becomes noticeably warm as you knead it.

How long do I have to apply it?

3–5 minutes at 25°C once kneaded.

When can I handle the repair?

After 60 minutes. That is a handling milestone, not full cure.

How long until it is fully cured?

24 hours at 25°C.

What colour does it dry?

Dark grey. It is supplied as a black hardener in a grey resin.

Can I use it on a petrol tank or radiator?

Yes. Selleys lists small engine parts, radiators and petrol tanks among its uses.

Can I use it to stop a leak in a pipe or gutter?

It is listed as suitable for sealing leaks and filling cracks in iron pipes, tanks and gutters. The surface must be clean and dry when you apply it.

Will it rust?

It is described as a non-rusting epoxy repair system, which is why it suits gutters, tanks and pipework.

What surfaces does it stick to?

Steel, ferrous metals, aluminium, other metals, glass, concrete, timber and most plastics.

Can I drill and tap it?

It can be machined, drilled, sawed, sanded and filed once cured — after the full 24 hours, not at the 60 minute handling point.

Can I paint over it?

Yes, once cured.

How hot can the repair get?

−40°C to +120°C continuous, with intermittent exposure to +140°C.

What temperature should I apply it at?

Between 5°C and 40°C.