Coagulant Dipping for Wearable Thickness
Safety. Acetic coagulants need PPE. Add acid to water, not the reverse. Warm leach is required. No copper or brass fittings in dip or leach contact. See Allergy and Skin Contact.
Executive summary
When straight multi-dip builds film too slowly, industrial practice moves to coagulant dipping: coat the former with a coacervant, dwell in compounded latex, withdraw a gelled shell.
A single coagulant dip typically yields 0.2–0.8 mm dry thickness. Straight dips sit around 0.01–0.05 mm per pass. Films above roughly 8 mil dry usually use coagulant because the film builds faster.
Primary levers are coacervant strength, dwell time (deposit often follows square-root-of-time kinetics), compound viscosity, and withdrawal speed. Follow with warm-water leach and humidity-aware dry. Use this after Former dip, mould cast, and flat spread routes you to a former.
When coagulant beats straight multi-dip
Straight dips leave a thin dry layer per pass. Coagulant destabilizes a thick gel layer in one dwell. That is a time-and-gauge trade. It is not automatic superiority without leach and stability discipline.
What is a coacervant?
A coacervant is a chemical coating on the former that makes liquid latex gel on contact. Dry coacervants (calcium chloride, calcium nitrate, cyclohexylammonium acetate) predominate. The solvent evaporates before the latex dip. Wet coacervants (for example acetic acid) are less common and appear in some chloroprene or fabric-lined glove contexts. Handbook plant formulations are industrial examples, not home mixing cards.
Coacervant families
Dry calcium salts are the default. Wet acid coacervants need extra PPE. Match coacervant family to your compound and former material.
Dwell time and thickness
Deposit thickness often rises with the square root of dwell time until the coacervant is depleted. Higher compound viscosity increases deposit. Long dwell can leave a strong inner gel with a weak outer fluid layer. Flow-off on withdrawal matters.
Quantitative curves are compound-specific. Revalidate for your latex and total solids.
What is wet gel strength?
Wet gel strength is how well the gelled latex holds together before cure. Plants track it with Chloroform Coagulant Number. Roughly 2–3 is the stable window. Below about 2, the deposit is “blown”: soft and collapsible on withdrawal.
Stability, pinholes, and air
Compound needs mechanical stability, predictable precure, and adequate wet gel strength. Entrapped air causes pinholes. Plants reject those. Mild vacuum on storage containers. Do not entrain air when filling the dip tank.
Weak wet gel usually traces to Chloroform Number or coacervant strength, not only salt percentage.
Leach, humidity, and second dip
Warm-water leach is required after coagulant dips. It improves cured properties and reduces discoloration.
Ideal plant conditions run 45–50% RH at about 20–26 °C. Too high: retained moisture depresses stress and tensile. Too low: skin-dry surface and poor second-dip lamination. Chloroprene films need more ambient dry than natural rubber before a second dip.
Decision cues
text
Target dry > ~0.2 mm one pass? → consider coagulant branch
Have warm leach + humidity control? → if no, fix environment before raising coacervant %
Weak wet gel / blown deposit? → check Chloroform No., not only Ca salt %
Second dip planned? → control first-film moisture (not skin-dry)When a deposit fails, name it: Liquid film defects.
Deep dives (optional)
Deep dive: Coacervant base formulations (plant examples)
Handbook examples include calcium chloride or calcium nitrate blends in alcohol or water, and cyclohexylammonium acetate variants. Alcoholic calcium nitrate, 20% calcium chloride, and aqueous acetic for chloroprene appear as plant cards. Label them as industrial examples.
Deep dive: Deposit kinetics
Industrial models relate deposit thickness to square-root dwell time and viscosity (Gorton θ′ = A + B√t, with a viscosity term). Quantitative curves are NR and total-solids specific.