# Former Dip, Mould Cast, and Flat Spread

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

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

## Executive summary

**Former dipping** builds film on a withdrawn shape.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. Straight dips are thin per pass;[^2] coagulant and heat-sensitized branches build thicker walls.[^3][^4]

Use after [Forming film from liquid latex](/literature-reviews/liquid-film-pathway).

---

## Forming map

Dipping deposits on a **former**; moulding replicates a **cavity interior**; spreading coats **fabric** with doctor blades (aqueous dry slower than solvent doughs).[^5][^6] Spreading, dipping, and impregnation were distinct routes in 1932.[^7]

---

## Former dipping

**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; porcelain resists coagulant and latex; exclude Cu/brass.[^3][^1]

Detail: [Coagulant dipping for wearable thickness](/literature-reviews/liquid-coagulant-dipping-wearable-thickness).

---

## Mould casting

**Plaster:** absorption + Ca²⁺ gel; dry completely before cure; erodes at sharp edges.[^9][^10] **Heat-sensitized (Kaysam):** closed mould, rotation, ~4 min @ 82 °C gel example; ammonium nitrate sensitizer just before use; avoid entraining air.[^10] **Slush** vs **rotational:** pour-out vs metered rotation. Stability vs wall uniformity. No rotational plaster moulds (too heavy/fragile).[^6]

Detail: [Heat-sensitized gelation](/literature-reviews/liquid-heat-sensitized-gelation).

---

## Flat spread

Doctor blade: sharp acute angle → thin coat, minimal strike-through; blunt perpendicular → thick coat, more penetration. Aqueous latex dries slower; run fabric slower than solvent doughs.[^5]

---

## 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
```

---

## Branch mix-ups

Kaysam rotation on an open tray. Spread-blade cards on plaster slush. Straight-dip pinhole logic on thick plaster cast without dry-before-cure.[^10][^3]

---

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

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

</details>

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

Coagulant-first vs latex-first on smooth formers appear to improve wetting. Final coagulant dip optional; recommended for CR.[^4]

</details>

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

Rotation gel 82 °C; leach 15–27 °C; dry 82 °C ≥3 h supported; cure 104 °C 20–60 min thickness-dependent.[^10]

</details>

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

Slush thickness: colloid stability + cavity geometry. Rotational thickness ≈ f(compound mass, cavity area).[^6]

</details>

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

Knife-over-roll and knife-over-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; tie-coat sequences (§17.2.3).
[^5]: *Polymer Latices Vol 3* — latex spreading methods; blade geometry (§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).