Wax Emulsion COW-3

In aqueous dispersion form, Wax Emulsion COW-3 is introduced as a waterborne paraffin wax preparation intended for hydrophobic modification of lignocellulosic board, paper stock, architectural coatings, and cementitious substrates. The manufacturer identifies COW-3 as a nonionic oil-in-water paraffin wax emulsion; the product designation distinguishes its emulsifier HLB and target particle size from adjacent grades in the same series. Incoming QC values typically fall within the following envelope: nonvolatile content by ISO 3251:2019 is 40–50 wt%; pH at 25 °C by ISO 976:2013 is 8.0–10.0; Brookfield viscosity at 20 rpm, spindle 2, 25 °C, by ISO 2555:2018 is 50–400 mPa·s; density by ISO 2811-1:2016 is 0.95–1.00 g/cm³; and mean particle diameter by laser diffraction per ISO 13320:2020 is 0.4–1.5 µm. The product is supplied as a low-viscosity, pumpable liquid that separates slowly under static conditions; gentle remixing before use restores uniformity. The paraffin active content contributes water-repellent film formation after water evaporation and paraffin crystallisation, while the emulsifier package governs colloidal stability, wetting on fibre surfaces, and compatibility with cationic or anionic wet-end additives.

When transferred on production-scale lines, COW-3 is preferably moved with air-operated double-diaphragm pumps fitted with PTFE diaphragms or with low-speed progressive cavity pumps. Centrifugal transfer pumps with closed impellers have produced shear-induced coalescence at the impeller tip; subsequent wax deposits collected in 100 µm line strainers and caused pressure drop across downstream bag filters. Bulk holding tanks should be cone-bottomed stainless steel or high-density polyethylene vessels with slow anchor agitation at 5–15 rpm. High-shear dispersing blades are not required and may accelerate particle aggregation. Batch-to-batch viscosity is controlled within ±50 mPa·s of the target value, although storage in unheated mezzanines across seasonal temperature swings can shift viscosity upward by 50–100 mPa·s without loss of chemical performance. The product freezes below 0 °C; freeze-thaw exposure destructures the emulsion through rupture of the interfacial film, and the resulting wax layer cannot be redispersed by normal plant-scale agitation. At relative humidity above 60%, open totes lose water and form surface skins; drums should be resealed after decanting.

What Storage and Handling Limits Govern COW-3 in Bulk Tank Settings?

Storage at 5–35 °C in closed containers is recommended. Material held beyond 6 months from production should be revalidated for pH, viscosity, and sieve residue on a 45 µm screen before use. The product is not freeze-thaw stable; if a tote is exposed to -5 °C for more than 24 h, full coagulation should be assumed. Avoid contamination with anionic polymer dispersions, strong acids, and high-valence cationic coagulants such as polyaluminium chloride; destabilisation may not appear immediately but results in stringy phase separation in downstream static mixers. Do not store in carbon-steel tanks without a dedicated internal liner, because long-term development of iron soaps increases the acid value of the organic phase and shifts the HLB balance of the emulsifier. The product should be diluted with process water at 20–35 °C under gentle mixing; adding water to cold emulsion can produce localised gel particles that plug spray nozzles. Tank cleaning with hot water at 50–60 °C and nonionic surfactant removes residual wax film; solvent cleaning is not required under normal operating conditions.

Within medium-density fibreboard and high-density fibreboard lines, COW-3 is injected into the blowline or refiner outlet after fibre drying but before resin blending. Addition levels of 0.5–2.0 wt% based on oven-dry fibre are common for standard MDF; grades requiring 24 h water absorption below 10% by EN 317:1993 may require 2.5–3.0 wt%. The emulsion is diluted with process water to 5–10 wt% solids before injection to limit localised wax deposition on refiner plates and blowline walls. In continuous MDF lines, viscosity drift from 150 mPa·s to 350 mPa·s over 6 months has been observed when totes are stored in unheated mezzanines; the drift correlates with increased backflushing frequency for 60–100 µm bag filters upstream of metering pumps. Paraffin wax from COW-3 deposits on fibre surfaces and reduces water uptake by interrupting capillary wicking at fibre lumens; it does not plasticise the resin matrix and does not improve internal bond strength. Processors should monitor blowline temperature because excessive heat above 160 °C can volatilise low-boiling fractions of the emulsifier package, reducing emulsion stability immediately before fibre contact.

When COW-3 Replaces Calcium Stearate Dispersions in Fibreboard Sizing

Substitution of COW-3 for calcium stearate dispersions shifts the hydrophobing mechanism from fatty acid soap deposition to paraffin film formation. Calcium stearate dispersions are typically high-pH, buffered products that also lubricate fibre surfaces during hot pressing; COW-3 provides less dry-out resistance because paraffin wax does not react with wood extractives. Volumetric dosing must be recalibrated because the density of COW-3 is lower than that of many 50 wt% stearate dispersions, and the solids content is also lower. Published data for specific press configuration comparisons is limited; mills evaluating this substitution should use EN 317:1993 thickness swell panels and monitor press cycle time, mat internal temperature, and blowline pressure drop. COW-3 should not be used as the sole release agent in urea-formaldehyde or melamine-urea-formaldehyde hot pressing; external release agent application remains necessary. When the product is introduced into an existing wax-emulsion line, the first 2–4 h of production should be run at reduced line speed to clear residual wax deposits from the former anionic product from the injection loop and static mixer.

In newsprint and lightweight coated paper furnishes, COW-3 can be added at the size press, at the wet end, or in pulp slurry. The nonionic character of the emulsion reduces the dosage of anionic optical brightening agents required, because charge competition is lower than with cationic wax emulsions. However, nonionic wax deposition onto cellulosic fibres is weaker without a cationic retention aid; retention aid selection must be validated on the specific furnish. Typical wet-end dosages range from 0.2–1.0 wt% based on oven-dry pulp, depending on Cobb values specified by ISO 535:2020. Addition after the last high-turbulence screen avoids shear-induced destabilisation; injection into a low-consistency stock line with a static mixer at 0.5–1.0 bar back pressure improves distribution. If alum or polyaluminium chloride is already present in the thick stock, jar tests at target ionic strength should be performed because bridging flocculation can produce visible wax specks in the sheet. At the size press, blends with starch at 50–60 °C should be prepared no more than 4 h before use to reduce the risk of wax agglomeration on the roll surfaces.

Electrolyte Tolerance and Coagulant Interactions in Paper Wet-End Chemistry

The tolerance of COW-3 to electrolytes is governed by the nonionic emulsifier cloud point and the thickness of the adsorbed steric layer. At conductivity above 3000 µS/cm in process water, storage and machine-dilution tests show increased particle collision efficiency. The emulsion should not be mixed directly with alum solution at pH 3.5–4.0; pre-dilution with process water to below 5 wt% solids is necessary to prevent local coagulation. In closed headboxes with high stock temperatures above 50 °C, the emulsion may deposit on headbox walls if the wet-end temperature exceeds the cloud point of the emulsifier; industrial runs with closed headboxes above 55 °C have shown wax deposition on slice lips. Published data for specific paper machine configurations is limited; mill trials should include a 10 µm screen residue test on machine stock. The product is generally compatible with starch sizes and polyvinyl alcohol, but avoid combination with amine-based defoamers that can modify the interfacial film and cause premature partial coalescence. If the mill uses hydrogen peroxide bleaching upstream, any residual peroxide should be completely decomposed before wet-end addition because oxidising conditions degrade the nonionic emulsifier and widen particle size distribution.

On exterior concrete flatwork, COW-3 is sprayed as a liquid membrane curing compound when formulated with additional coalescing solvent and UV-absorbing additive. The paraffin film reduces moisture loss from fresh concrete; curing compound performance is evaluated by ASTM C309-19 for liquid membrane-forming curing compounds and water retention by ASTM C156-20. Spray application rates of 4–6 m²/L are typical for a single coat on a steel-trowelled surface; over-application above 3 m²/L produces a thicker film that may reduce traction. The product is diluted with water before spray application; airless spray equipment with 0.3–0.5 mm orifice tips is used on small-to-medium pours, while larger finishers operate with high-pressure piston pumps. If the emulsion is used under hot, windy conditions above 35 °C, evaporation of the water phase before film coalescence causes pinholing; re-wetting of the surface or applying at lower ambient temperature reduces this defect. The wax film is not intended as a final wear surface and is removed by traffic or by subsequent surface preparation.

Film Coalescence Is Governed by Paraffin Crystallinity

During drying, water evaporation concentrates the paraffin droplets until the emulsifier film ruptures and paraffin crystallises into a hydrophobic network. The minimum film-forming temperature is controlled by the melting range of the paraffin fraction, which typically spans 45–60 °C; below this range, the dried deposit is waxy and discontinuous. High-gloss or semi-gloss architectural coatings containing COW-3 may show surface haze if the paraffin particles are not adequately smaller than the visible light wavelength; grades with D50 above 1.0 µm produce more haze than grades below 0.5 µm. In exterior wood stains, the wax improves water beading after exposure to 100 h of UV weathering per ASTM G154-16, but the film becomes hydrophilic after surface erosion removes wax from exposed planes. Intercoat adhesion is assessed by ASTM D3359-17; wax migration to the coating surface can reduce cross-cut adhesion if COW-3 is added above 5.0 wt% in a topcoat. Formulators should therefore limit topcoat additions to 2.0–5.0 wt% and confirm adhesion before production.

Compared with anionic paraffin wax emulsions, COW-3 does not require pH adjustment with ammonia to maintain colloid stability, because the nonionic emulsifier is not ionised. Anionic emulsions are often destabilised by calcium ions from wood extractives and process water; COW-3 tolerates higher water hardness but must still be protected from high-valence coagulants. Relative to synthetic polyethylene wax emulsions, COW-3 produces softer films with lower scuff resistance and lower melt viscosity after drying. Relative to carnauba or candelilla wax emulsions, the paraffin active in COW-3 is lower in acid value and ester functionality, which reduces reactivity with alkyd resins and lowers yellowing in clear finishes. These differences make COW-3 more suited to internal hydrophobic modification where hardness is not required, rather than surface abrasion resistance.

Users evaluating COW-3 for food-contact paper and board should verify the specific formulation under 21 CFR 176.170 and 21 CFR 176.180; the manufacturer regulatory statement must list the emulsifier CAS numbers and paraffin wax melting range. For architectural coatings, VOC content determined by ISO 11890-2:2020 is typically below 30 g/L in the wet product, but the exact value depends on residual neutralising agent and coalescing solvent; the emulsion itself is waterborne and not classified as flammable. Under CLP, the product is not expected to require hazard labelling for acute toxicity or corrosion; nonetheless, spills on smooth floors generate slippery films when dried and should be cleaned with warm water and nonionic detergent. The product has not been validated as a direct food additive; indirect contact is assessed through migration limits in the relevant national legislation. For REACH compliance, downstream users should confirm that the supplier registration covers paraffin wax and the specific emulsifier substances under the applicable tonnage band.

COW-3 is not recommended for use below 5 °C in exterior architectural topcoats, because film formation of the coating binder may proceed while paraffin droplets remain crystalline, reducing intercoat adhesion. The emulsion is also not recommended for combination with amine-based defoamers, high-acid acrylic dispersions, or borate salts unless a detailed storage stability test is performed at 40 °C for 28 days. In industrial practice, batch-to-batch variation in paraffin melting range can shift the minimum film-forming temperature by 2–5 °C; users should monitor the melting point of extracted wax by DSC. No upper use temperature is defined for the dried wax film, but the film softens near the paraffin melting range and should not be specified as a high-temperature release surface.