Demoulding time sits in a few heads: HR for cement product makers

Stand in a cement product yard at first light and watch who decides when yesterday's casting comes out of the moulds. It is rarely the owner or the supervisor. It is one or two older hands who press a thumbnail into a slab edge, tap a pipe collar with a spanner and glance at the sky. They know that a cold, damp night means another few hours. They know a fibre mould for a jaali behaves differently from a steel mould for a manhole cover. None of it is written anywhere.

Our cement product makers page puts this strain at the top of its list. It sounds like concrete science, yet the root sits with who knows what. The wider group page on construction materials plants covers the neighbouring trades.

• Section thickness: a thin jaali panel and a thick kerb stone cast on the same morning are ready hours apart.
• Weather: cold nights, monsoon damp and summer heat all shift the safe strip time.
• Cement lot and mix: a new cement batch, more fly ash or a change in sand changes setting.
• Mould type: steel, fibre or rubber moulds release and hold heat differently.
• Product shape: pipe sockets, manhole cover rims and fence post ends crack first if stripped early.
• Vibration or spinning quality: a poorly compacted piece needs more time and more care.

When the senior hands are on leave, sick or have left, the newer crew follows the day's count. It strips at the usual hour regardless of the night's weather. The pieces look fine at stacking. Days later, after curing, hairline cracks appear at pipe sockets, slab corners chip, and kerb stones show weak arrises. Some fail the buyer's inspection. Moulds suffer too: a piece forced out early drags against the mould face, and rough levering bends edges. The damaged mould then spoils every piece cast in it until someone notices.

Most of this loss is never traced back to the strip. It is blamed on the cement, the sand or the curing attendant. That is why the problem keeps returning.

Old yard hands picked it up over many seasons behind their own ustads. Nobody asked them to explain it, and they may not find it easy to put into words. The yard is paid on pieces cast or stripped per day, so speed is rewarded and patience is not. Supervisors in these yards often came up as mould hands themselves and have little practice in planning who learns what. And because the seniors are always there on normal days, the gap only shows when they are not.

1. 1

   Write a strip card per product

   Sit with the senior hands and write, for each product, the normal strip time and how it changes with weather, mix and mould. Use their words, not a textbook's.

2. 2

   Chalk the casting time

   Mark each mould or pallet with the casting time and date, so anyone can see how long it has been.

3. 3

   Name the release hand

   One person per shift decides when a batch is stripped, signs the card and is backed when he says wait.

4. 4

   Give every senior an apprentice

   The learner makes the call first; the senior confirms or corrects, every morning, for a season.

5. 5

   Log the stripping hand per batch

   One line per batch in the casting register, so a crack spotted after the tank links back to a strip hour and a gang.

6. 6

   Pay on sound pieces

   Pay or praise for good pieces after curing, not for pieces stripped.

Product, size and mould type.
Normal strip time after casting, in hours.
Add time when: cold night, monsoon damp, new cement lot, extra fly ash.
Reduce time only when: the senior hand confirms, in hot dry weather.
Checks before stripping: edge test, tap test, corner check.
Who may release: named release hand per shift.
Curing after strip: method and days.
Signed by the senior hand who wrote it, with date.

Winter needs its own line. Spun RCC pipes, socket-and-spigot collars and precast septic tank rings all hold heat differently, and a December fog can add half a shift. Some yards use wet hessian, polythene sheeting or a steam box to speed the early set; each changes the card. Keep a thermometer and a cement lot board beside the casting bay, so the release hand reads conditions rather than guessing them.

If the yard pays a mould hand the same as a helper, it signals that judgement does not matter. Give senior mould and release hands a grade of their own, a higher daily rate and an apprentice to teach. Our note on roles in casting yards explains how to give the release step a clear owner. The learning process for cement product yards covers passing mould care to newer hands. Batch and crew records that link cracks to strips are set out in records for casting yards.