# Former Dip vs Mould Cast vs Flat Spread: Liquid Latex Forming Choices

Human page: https://retifist.com/literature-reviews/former-dip-vs-mould-cast-vs-flat-spread

> **Safety.** Liquid latex concentrates carry ammonia and metal-hygiene rules (no copper/brass in dip/leach contact).[^1] Coagulant salts and heat sensitizers are plant chemicals. See [Allergy and Skin Contact](/literature-reviews/allergy-and-skin-contact).

## Executive summary

Liquid latex does not have one casting method. **Former dipping** builds film on a withdrawn shape. **Mould casting** gels inside a cavity (plaster or heat-sensitive metal; slush or rotational). **Spreading** is industrial textile proofing, not a tabletop puddle. Straight dips are thin per pass;[^2] coagulant and heat-sensitized branches build thicker walls.[^3][^4] Use this after [Sheet vs Liquid Film Pathways](/literature-reviews/sheet-vs-liquid-film-pathways) confirms liquid latex work.

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## Forming map

Dipping deposits on a **former**; moulding replicates a **cavity interior**; spreading coats **fabric** with doctor blades (slower dry than solvent doughs).[^5][^6] Spreading, dipping, and impregnation were distinct routes historically.[^7]

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## Former dipping branch

**Straight dip:** ~0.01–0.05 mm dry per pass — multi-dip for gauge.[^2] **Coagulant dip:** coacervant + dwell gel shell; >~8 mil dry usually coagulant for economics.[^3][^4] Warm leach and staged cure follow.[^8] Rotate formers; exclude Cu/brass.[^3][^1]

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## Mould casting branch

**Plaster:** absorption + Ca²⁺ gel; dry completely before cure.[^9][^10] **Heat-sensitized (Kaysam):** closed mould, rotation, ~4 min @ 82°C gel example; sensitizer just before use.[^10] **Slush** vs **rotational:** pour-out vs metered rotation — stability vs wall uniformity.[^6]

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## Flat spread branch

Industrial blade angles control strike-through; aqueous latex dries slower — run fabric slower.[^5]

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## Decision tree

```text
1. Geometry → positive former (dip) | cavity (cast) | fabric line (spread)
2. Thickness → straight dip | coagulant (>8 mil) | slush/rotational
3. Mould → plaster (dry before cure) | heat-sensitized metal (Kaysam)
4. Metal hygiene → no Cu/brass in dip/leach
5. Spread equipment → doctor blade line vs not documented hobby flat-bed
```

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## Do-not-mix callouts

Coagulant on sheet-based work; Kaysam rotation on open tray; spread blade cards on plaster slush; straight-dip pinhole logic on thick plaster cast without dry-before-cure discipline.

---

<details>
<summary>Deep dive: Straight dip thickness vs viscosity</summary>

Log-viscosity scaling; 0.01–0.05 mm single-dip band.[^2]

</details>

<details>
<summary>Deep dive: Tie-coat sequences</summary>

Coagulant-first vs latex-first on smooth formers.[^4]

</details>

<details>
<summary>Deep dive: Kaysam cycle</summary>

Heat-sensitizer rotation, leach, supported dry, cure windows.[^10]

</details>

<details>
<summary>Deep dive: Slush vs rotational</summary>

Thickness control trade-offs.[^6]

</details>

<details>
<summary>Deep dive: Spreading blade geometry</summary>

Knife-over-roll and diaphragm arrangements.[^5]

</details>

---

## Endnotes

[^1]: Vanderbilt Latex Handbook — dip equipment materials (Ch 16).
[^2]: Polymer Latices Vol 3 — Application of Latices — straight dip thickness (§17.2.2).
[^3]: Vanderbilt Latex Handbook — formers, coagulant economics (Ch 16).
[^4]: Polymer Latices Vol 3 — coagulant dipping (§17.2.3).
[^5]: Polymer Latices Vol 3 — latex spreading methods (§19.2.1).
[^6]: Polymer Latices Vol 3 — moulding/casting; slush vs rotational (§23.3.1).
[^7]: NBS Letter Circular 321 — process map (1932).
[^8]: Vanderbilt Latex Handbook — leach and cure (Ch 16).
[^9]: Polymer Latices Vol 3 — plaster mould gel (§23.3.1).
[^10]: Vanderbilt Latex Handbook — porous cast and Kaysam cycle (Ch 19).