# Forming Film from Liquid Latex
Human page: https://retifist.com/literature-reviews/liquid-film-pathway
> **Safety.** Concentrates carry ammonia odor, freeze risk, and metal-fitting hygiene. Coagulant dips use calcium salts as plant tools. Protein and accelerator chemistry can matter for skin contact. See [Allergy and Skin Contact](/literature-reviews/allergy-and-skin-contact) and [Liquid ventilation and ammonia](/literature-reviews/liquid-ventilation-ammonia).
## Executive summary
Start from liquid latex (aqueous colloidal polymer dispersion) and form a film by dipping, casting, or spreading.[^1] A film from *raw* latex is not a saleable article until compounded. Elastomeric latex typically includes vulcanization. A vulcanized film is expected to stretch to at least twice its length and recover.[^1]
Forming method: [Former dip, mould cast, and flat spread](/literature-reviews/liquid-former-dip-vs-mould-cast-vs-flat-spread). Bottle fields: [Decoding liquid latex bottle labels](/literature-reviews/liquid-decoding-bottle-labels).
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## Feedstock
ISO 2004 specifies ammonia-preserved centrifuged or creamed NR *concentrate* (HA, LA; 2024 also names MA).[^2] ASTM D1076 covers concentrated, ammonia-stabilized NR latex categories and **does not apply to compounded** concentrates.[^3] A consumer bottle labeled “liquid latex” is not automatically D1076 concentrate.
ISO 1382 vulcanization language defines a *state of the rubber*, not a forming method.[^1]
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## Forming loci
**Dipping.** Immerse a former, withdraw a deposit, repeat for thickness, then leach / dry / vulcanize as required. Types: straight, coagulant, heat-sensitized, electrodeposition.[^4][^5] Straight (no coagulant) dry deposit typically **~0.01–0.05 mm** per single dip; multi-dip builds thickness and misaligns pinholes.[^5]
Primary coagulants include acetic/formic acids and calcium nitrate / calcium chloride.[^1] Most dipped articles with dry film thicker than 8 mils use coagulant for economics (faster build).[^1] Warm-water leach is required for coagulant-dipped products.[^1]
**Casting.** Plaster: water absorption plus calcium ions. Metal moulds need heat-sensitized latex. Slush vs rotational.[^4] See [Heat-sensitized gelation](/literature-reviews/liquid-heat-sensitized-gelation).
**Spreading.** Lab: compounded latex on glass, wire-wound knife; Anode (coagulant then latex) vs Teague (latex first); leach 20–30 min at 40–50 °C.[^1] Industrial: conveyor / multi-ply vulcanizable latex; successive coats with drying between.[^6][^7] See [Home-cast latex film](/literature-reviews/liquid-home-cast-film).
NBS (1932) process map: spreading, dipping, electrodeposition, chemical deposition, foam.[^8]
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## Plant discipline
Equipment contacting latex must be free of copper, brass, or galvanized iron. Rotate formers 180–360° after dip. Former glaze → shiny; bisque/sandblast → dull.[^1]
Air in compound → pinholes (reject). Ideal window ~20–26 °C, 45–50% RH.[^1] Exam-glove thickness 0.10–0.20 mm is glove geometry.[^4] Gloves are about half of NRL consumption in the Practical Guide dipping chapter.[^4]
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## Prevulcanized vs post-cure
Prevulcanized latex is vulcanized in the liquid. Proper prevulc can approach conventional post-dry properties (~4,000–5,000 psi tensile when particles integrate). Overcure makes a short, weak deposit.[^1] Gloves from prevulcanized latex need only warm-air drying.[^1]
Historical: vulcanized latex → deposit and dry; natural latex ordinarily vulcanized after forming.[^8]
Prevulc tensile maxima occur at lower relaxed modulus (~0.4–0.5 MPa) than postvulc (~0.8 MPa) because high crosslink can interfere with particle integration on drying.[^5]
Post-form vulcanization of dried compound is a separate branch (handbook example: air-dry then circulating warm air at 93 °C).[^1]
**Contradiction, keep loci labeled:** Practical Guide casting section: strength is always low for film from prevulcanized compound.[^4] Vanderbilt prevulc definition: proper prevulc can approach conventional properties.[^1]
Do not treat “I bought a bottle” as prevulc dry-only. See [Prevulcanized consumer latex](/literature-reviews/liquid-prevulcanized-consumer-latex).
Commercial prevulc TDS examples exist (PVultex LA prevulc, TSC ~60%, frost-sensitive; Revultex distributor TDS, ASTM D412 films 0.12–0.15 mm).[^9][^10]
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## Polymer family mix-ups
Synthomer SyNovus-class TDS is coagulant multi-dip **nitrile**.[^11] Hevea NR, prevulc NR, and nitrile are different polymers. See [Synthetic lattices](/literature-reviews/liquid-synthetic-lattices).
REVACRYL-class styrene-acrylic dispersions are the wrong polymer family for prevulcanized NR.
Historical cement dipping in benzene or gasoline is a different process from latex dipping.[^8]
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## When this pathway fits
Form thickness, color, or shape from liquid. Inherit metal hygiene and the idea of leach for coagulant work.
Joins: [Liquid adhesives and seam integrity](/literature-reviews/liquid-adhesives-and-seam-integrity). Storage: [Liquid aging, storage, and care](/literature-reviews/liquid-aging-storage-and-care). Defects: [Liquid film defects](/literature-reviews/liquid-film-defect-atlas).
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Deep dive: Dip / cast / spread tree
Latex polymer need not be masticated; high molecular weight versus dry-rubber processing.[^4] Gorton: thickness increases approximately linearly with log(viscosity) when solids and viscosity co-vary by dilution. Condoms commonly two simple dips.[^5]
Dip-compound: mechanical stability, chloroform-number example 2–3, wet-gel strength, air-free; dilute with deionized water. Wet-gauge levers: % TSC, coagulant strength, dwell, viscosity, withdrawal speed. Webbing → weak spot when the web breaks.[^1]
Casting prevulc preferred for some solid articles (skip product vulcanization) but casting-section film strength always low.[^4] Heat-sensitized moulding history (Metallgesellschaft; Kaysam zinc-ammine) requires thorough leach after gel.[^5]
Deep dive: Prevulc tank and TDS
Handbook prevulc example: about an hour at 79 °C. Clarify to remove excess sulfur and zinc oxide.[^1] US 3,755,232: H₂O₂ / activator prevulc; uses include adhesives, coatings, dips, threads, foams; additional film cure may still use sulfur, ZnO, accelerators.[^12]
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## Endnotes
[^1]: *The Vanderbilt Latex Handbook* — latex as aqueous colloidal dispersion; raw film needs compounding; vulcanized-film stretch/recover; prevulc liquid-state (~4,000–5,000 psi; overcure short/weak); Ch 16 dipped goods (metal hygiene; former rotation; leach required for coagulant dips; prevulc gloves dry-only; glaze vs bisque; >8 mil coagulant economics; RH window; pinholes/webbing; primary coagulants); Ch 14 lab spread (Anode vs Teague; leach example); post-form oven example.
[^2]: ISO 2004:2024 — ammonia-preserved centrifuged or creamed NR latex concentrate (HA, LA, MA). Concentrate specification, not a consumer-bottle taxonomy.
[^3]: ASTM D1076 — concentrated, ammonia-stabilized NR latex categories; does not apply to compounded concentrates.
[^4]: *Practical Guide to Latex Technology* — dipping classes (straight / coagulant / heat-sensitised / electrodeposition); gloves as large NRL share; exam-glove thickness as glove geometry; casting (plaster vs metal; slush vs rotational; prevulc film strength always low in that casting section).
[^5]: *Polymer Latices Vol 3 — Application of Latices* (Blackley) — §17.2 principal dipping processes (Gorton single-dip ~0.01–0.05 mm; multi-dip pinhole misalignment); §16.2.4 thin-film crosslink vs tensile (postvulc ~0.8 MPa; prevulc ~0.4–0.5 MPa; particle integration); §23.3.4 historical heat-sensitized moulding.
[^6]: US Patent 2,415,028 — historical industrial spreading of vulcanizable latex (conveyor / multi-ply).
[^7]: US Patent 2,129,607 — successive coats of latex with drying between.
[^8]: NBS Letter Circular 321 — 1932 process map; vulcanized latex deposit-and-dry vs natural latex ordinarily vulcanized after forming; historical cement dipping in benzene or gasoline.
[^9]: Corrie MacColl PVultex PVML TDS — LA prevulcanised NR; dipping uses; TSC ~60%; frost-sensitive.
[^10]: Revultex prevulcanized NR latex TDS (distributor PDF) — dipped articles, cold casting; example ASTM D412 films in the glove-class thickness band.
[^11]: Synthomer SyNovus Plus TDS — coagulant multi-dip nitrile latex. Parallel synthetic film pathway.
[^12]: US Patent 3,755,232 — H₂O₂ / activator prevulc; uses include adhesives, coatings, dips, threads, foams.