A recess former is the rubber, plastic or magnetic part that holds the lifting anchor against the mould face and forms the void around the anchor head. It is bought as a mould consumable and it behaves as a safety component: the shape of that void decides whether the lifting clutch can reach under the head and fully engage — and a partially engaged clutch is how elements get dropped. So: match the former to the anchor's load class, fix it rigidly and flush so no concrete gets in, never vibrate it directly, twist it free at de-moulding rather than levering, and patch the recess afterwards, because that void is a hole straight through the concrete cover to the anchor steel.
1. What people think it is, and what it actually is
Almost every article about recess formers is a shopping guide: rubber or magnetic, which size, what price. That framing is the problem, because it is how a safety component ends up being bought by whoever is ordering mould consumables.
2. The void is the safety feature
Think about what has to happen on site. The clutch arrives, and its claw has to get in under the ball head, seat, and be able to rotate as the element turns. All of that happens inside a hole that was cast weeks earlier by a piece of rubber.
3. Rubber, plastic or magnetic — decided by the mould, not by preference
| Type | How it fixes | Best on | Why you'd pick it |
|---|---|---|---|
| Magnetic recess former | Integrated magnets clamp to the mould | Steel moulds and steel casting beds | ✓ No drilling, welding or gluing; reposition instantly. The default for high-turnaround steel-bed plants. |
| Rubber recess former | Bolted / nailed via fittings, or held by a magnet plate | Most mould types | ✓ It flexes — so it twists free at de-moulding without chipping the recess edge. That flexibility is a feature, not a compromise. |
| Plastic recess former + fitting | Bolted or nailed through the fitting | Timber and plastic moulds; repeatable low-cost use | Cheapest per cast where the fixing method is mechanical anyway. |
| Double-head former | As above | Double-head anchors | Matched to the anchor geometry — you cannot substitute a single-head former. |
4. Match the load class — the former, the anchor and the clutch
The lifting system is designed as a matched set, and the recess former is part of that set — not an afterthought bolted onto it.
Two practical consequences:
- Buy them together. The former is matched to the anchor's load class, and the anchor is matched to the clutch's. Sourcing the former separately on price is how a set stops being a set.
- Use the former, always. The former is what guarantees the anchor is in the right position at the right depth — which is exactly what makes the clutch able to couple quickly and safely on site. Improvising with tape and a plastic cup does not do that.
5. The five moments where it goes wrong
Every recess-former defect happens at one of five moments. All five are process failures, and all five are free to prevent.
Fixing to the mould
Magnets or bolts on steel; nails on timber. Contact face clean and degreased — a greasy face lets the magnet go during the pour.
Seating flush
The big one. If it is not sealed flush to the mould face, concrete and laitance get into the void. Fouled recess = clutch can't seat.
Pouring & vibrating
Compact around it, but never put the poker on the former. Direct vibration walks it out of position — and moves the anchor with it.
De-moulding
Wait for cure, then twist and pull. Rubber flexes free. Do not lever with a bar — prying chips the recess edge.
Patching
After the lift, fill the recess with repair mortar. Skipping this leaves a corrosion path to the anchor. See below.
6. The patch nobody does
Here is the step that disappears from every method statement. Once the element is set and the clutch comes off, there is a hole in the concrete surface that runs straight down to the anchor steel.
That hole sits inside the concrete cover. It is a direct, unobstructed route for water and chloride to reach the anchor — the exact thing the cover exists to prevent. If you have read our guide to cover and spacers, you already know why this matters: everything the durability calculation assumed is undone by an open recess.
| If the recess is… | What happens |
|---|---|
| Left open | ✕ A direct corrosion path to the anchor steel. Rust, staining, and eventually spalling around the recess. |
| Filled with any old mortar, poorly compacted | ✕ A void behind the patch — water gets in and cannot get out. Often worse than leaving it open, because now it's hidden. |
| Filled with a proper repair mortar, well bonded and compacted | ✓ The cover is restored. The element is finished. |
7. Frequently asked questions
What does a recess former actually do?
It does two jobs at once. It holds the lifting anchor in exactly the right position against the mould face while the concrete is poured and vibrated, and it forms the void — the recess — around the anchor head. That void is what the lifting clutch has to reach into on site. So the former is not just holding a part in place; it is casting the shape of the space that the clutch must work in.
Why is a recess former a safety component and not just a mould accessory?
Because the geometry of the void it leaves decides whether the clutch can fully engage under the anchor head. If the recess is the wrong shape, too shallow, or partly filled with concrete because the former was not sealed flush to the mould, the clutch cannot seat and rotate properly. A partially engaged clutch is precisely the failure mode that drops precast elements. The former costs very little and controls a great deal.
Does the recess former have to match the anchor's load class?
Yes. The recess former must be matched to the load class of the anchor it is holding, because the void has to suit the head size and the clutch that will engage it. A former from a different class will position the anchor at the wrong depth relative to the surface, or leave a void the clutch cannot work in. Match the former, the anchor and the clutch as a set — that is how the system is designed to be bought.
Rubber, plastic or magnetic recess former — which one?
It depends on the mould. Magnetic formers clamp straight onto a steel mould with no drilling, welding or gluing, which is why they suit steel casting beds and high-turnaround plants. Rubber formers flex, which makes them easy to twist free at de-moulding without damaging the concrete edge, and they suit a wide range of mould types. Plastic formers with fittings suit repeatable, low-cost use where the fixing method is bolting or nailing. The decision is driven by the mould material and the fixing method, not by preference.
How should a recess former be fixed to the mould?
Rigidly and flush. On steel moulds use magnets or bolts; on timber, nails or screws. The contact face must be clean and degreased so magnets or adhesive hold. Two failure modes matter: if the former can shift during the pour, the anchor ends up out of position; and if it is not sealed flush against the mould face, concrete or laitance gets into the void and the recess is fouled. Do not vibrate the former directly — keep the poker off it.
How do you remove a recess former without damaging the concrete?
Wait until the concrete has cured enough, then twist and pull the former free gently. Rubber formers flex and release without spalling the recess edge. Do not lever it out with a bar: prying against green concrete chips the edge of the recess, and a damaged recess edge is exactly what stops the clutch seating cleanly later.
Does the recess need to be patched after lifting?
Yes, and this is the step most often skipped. The recess is a void that reaches from the concrete surface down to the anchor steel — it sits inside the cover zone and is a direct route for water and chloride to the anchor. Once the element is set and the clutch is removed, the recess must be filled with a proper repair mortar, well compacted and bonded. An unpatched recess is a designed-in corrosion path.
What goes wrong most often with recess formers?
In order: the former moves during the pour because it was fixed to a greasy or dirty mould face, so the anchor ends up out of position; concrete gets into the void because the former was not seated flush, so the recess is fouled and the clutch will not seat; the former is levered out instead of twisted, chipping the recess edge; and the recess is never patched, leaving a corrosion path into the element. All four are process failures, and all four are free to prevent.
Can a damaged or worn recess former be reused?
A former is a consumable, and a worn one no longer forms the void it is supposed to. A rubber former that is split, deformed or has lost its shape will not seal against the mould and will not produce a clean recess — which puts you straight back into the fouled-recess failure. If it no longer seats flush and holds the anchor square, replace it. It is one of the cheapest items in the whole lifting system.
References
- VDI/BV-BS 6205 — the guideline series for lifting inserts and lifting insert systems for precast concrete elements, which governs the matched anchor / clutch / former system.
Need recess formers matched to your anchor load classes?
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