MeFoam-S (Universal Silicone Defoamer Compound, Non-Modified PDMS): Lower-Cost Industrial Defoamer for Non-Shelf-Critical Coatings and Adhesives
SEMITECH MeFoam-S is the universal alkyl-silicone defoamer — non-modified PDMS + hydrophobic silica — for industrial coatings, adhesives, and oil-water separation where shelf-life persistence matters less than cost-per-kg active. ~40% cheaper than polyether-modified MeFoam-PE. 25 kg HDPE pail, 2–4 week ex-China lead time.
Contents
| Pure PDMS | 0.05–0.5% | ~40% cheaper |
|---|---|---|
| Chemistry | Typical loading | vs MeFoam-PE |
Chemistry & Specifications
Pure non-modified PDMS, 1,000–5,000 cP, hydrophobic silica nucleator; lowest-cost silicone defoamer.
Non-modified PDMS (350–1,000 cP virgin) at 80–85%, hydrophobic silica at 5–8%, dispersing aid 0.5–2%. Compound viscosity 1,000–5,000 cP. Two key characteristics: (1) ~35–45% cheaper than polyether-modified grades; (2) shorter shelf-life in waterborne formulations — pure PDMS phase-separates in 4–8 weeks vs 12+ months for polyether-modified.
Defoaming Mechanism: PDMS Spreading + Silica-Nucleated Bubble Rupture
Non-modified PDMS provides strong surface-tension differential; spreads aggressively but hydrophobic in waterborne.
More aggressive spreading than polyether-modified (PDMS 20–22 mN/m vs polyether-PDMS 22–25 mN/m), giving 10–30 sec knockdown. Phase-separates from waterborne formulations over time, limiting shelf-life.
- Loading 0.05–0.20% — solvent-borne coatings (alkyd, polyurethane, epoxy)
- Loading 0.10–0.30% — industrial waterborne coatings (factory-applied, ≤8 wk shelf life)
- Loading 0.10–0.50% — adhesive emulsions (fast-turnover)
- Loading 0.05–0.30% — oil-water separation, hydraulic fluid de-aeration
In solvent-borne coatings, MeFoam-S is the standard choice — the solvent provides carrier compatibility, eliminating the need for polyether modification. Avoid for retail-channel waterborne paint with 12+ month shelf life.
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Applications & Formulation Guidance
Solvent-borne coatings (largest), industrial waterborne, adhesive emulsions, oil-water separation, hydraulic.
Solvent-borne coatings (largest) — alkyd enamels, PU wood finishes, epoxy floor coatings at 0.05–0.20%. Industrial waterborne with <8 week shelf life — coil coating, OEM primer at 0.10–0.30%. Adhesives — PVAc, EVA, vinyl-acrylic at 0.10–0.50%. Oil-water separation — petrochemical and food-processing at 50–500 ppm. Hydraulic fluid de-aeration — 0.005–0.050%.
Procurement, Storage and Quality Control
CoA per shipment; 25 kg HDPE pail; 12-month sealed shelf life; non-flammable; compatibility testing required.
CoA per batch: viscosity (1,000–5,000 cP), silicone content (≥92%), silica (5–8%), water (≤0.5%). MOQ 25 kg. Lead time 1–2 weeks Asia, 4–6 weeks Europe/North America. Re-homogenise drums stored >6 months (silica settles). Compatibility testing mandatory — pure PDMS defoamers are more prone to fish-eyes than polyether-modified. REACH-registered; FDA 21 CFR 175.300 for indirect food-contact; not for direct food-contact.
MeFoam-S Specification Sheet
SEMITECH stocked grade; CoA per batch.
| Property | Specification | Test Method |
|---|---|---|
| Chemistry | Non-modified PDMS + hydrophobic silica | — |
| Form | 100% active compound | — |
| PDMS virgin viscosity | 350–1,000 cP | Brookfield |
| Active silicone content | ≥92% | Solvent extraction |
| Hydrophobic silica content | 5–8% | Ash analysis |
| Appearance | Translucent off-white to grey viscous liquid | Visual |
| Density (25°C) | 0.96–0.99 g/cm³ | ASTM D1475 |
| Compound viscosity (25°C) | 1,000–5,000 cP | Brookfield |
| Surface tension (1% aq.) | 20 ± 2 mN/m | Du Noüy ring |
| Water content | ≤0.5% | Karl Fischer |
| Flammability | Non-flammable (flash point >300°C) | ASTM D93 |
| Solubility | Soluble in toluene, esters, hydrocarbons; insoluble in water (requires emulsification) | — |
| Packaging | 25 kg / 200 kg HDPE pail or drum | — |
| Shelf life | 12 months sealed below 30°C | — |
FAQ
+When should I choose MeFoam-S over MeFoam-PE?
Choose MeFoam-S when: coating consumed within 1–8 weeks, cost is the primary driver, and surfactant stabilisers maintain emulsion stability. Choose MeFoam-PE for retail paint with 12+ month shelf life and shipping-temperature cycling.
+Will MeFoam-S cause surface defects on wood finishes?
Risk is moderate. Mitigations: lower loading from 0.20% to 0.10%, use higher-viscosity variant, or blend 10–20% polyether-modified grade. Run draw-down test on actual substrate before scaling.
+What is the cost differential vs MeFoam-PE?
MeFoam-S USD 1.7–2.5/kg; MeFoam-PE Low-MW USD 3.1–3.9/kg. 35–45% favouring MeFoam-S. Significant in industrial coatings where margins are 5–10%.