Silicone Antifoam & Defoamer Supplier | Bulk Emulsions & Compounds

Buying silicone antifoam by the drum or tote is two decisions, and the price sheet shows only one. The first is cost per pound of active silicone, where a 50% concentrate beats a 10% ready-to-dose emulsion on freight and water. The second is what the silicone does after the foam is gone. The same insoluble droplet that ruptures a bubble film will coat a membrane, foul a reboiler, or crater a topcoat if the grade is wrong for the system.

The short version: a silicone antifoam is polydimethylsiloxane (PDMS, CAS 63148-62-9) carried with hydrophobic silica. RawSource supplies it as a water-dispersible silicone antifoam emulsion at about 10% active silicone (9 to 13% on the current grade; higher-active concentrates by quote), as a 100% PDMS-silica compound (simethicone), and as neat PDMS fluid by viscosity, in pails, drums, and IBC totes, with a Certificate of Analysis (CoA) on every lot. Emulsion for aqueous foam, compound or fluid for non-aqueous and high-temperature duty, and ladder the dose from the low end on your own liquid.

What is a silicone antifoam?

A silicone antifoam is a formulation, not a single molecule. The carrier is PDMS, a silicone fluid that is insoluble in water and spreads across a foam film on contact. Dispersed in it are hydrophobic silica particles that do the mechanical work: they bridge the thinned film, the water de-wets off them, and the wall tears. That sequence runs at parts per million. The full mechanism is in how silicone antifoam works.

The buying question is delivery form. A silicone antifoam emulsion is the PDMS-silica active pre-broken into fine droplets in water, sold by active percentage. A 100% compound is PDMS plus hydrophobic silica with no water. A neat PDMS fluid is the silicone alone, sold in centistokes, the building block for blenders. Same chemistry, three ways to reach the foam. For most plant foam in water, the emulsion wins because its droplets are already sized to enter and spread evenly.

Emulsion or compound: how to choose

Match the form to the system, the active percentage to your logistics, and the grade to whatever sits downstream of the foam.

Active percentage is a freight decision more than a chemistry decision. A 10% emulsion drops straight into a day tank and forgives rough handling. A 50% concentrate ships less water per pound of silicone, which matters on totes, but needs on-site dilution and cleaner dosing practice. Cheaper per pound of active, less forgiving per gallon. The silicone defoamer selection guide walks the grade decision; the defoamer dosing guide carries starting ranges and feed points by system, so this page does not repeat them.

Applications by industry

Wastewater and water treatment

Aeration basins, DAF units, digesters, and scrubbers foam on detergents, grease, and startup sludge. A silicone antifoam emulsion knocks that chemical foam down at ppm when spot-dosed at the foam surface or the aeration inlet.

The limit is biological foam. Silicone knocks down the symptom of a filamentous bloom, not the sludge-age problem behind it, and standing-dosing an insoluble oil into a basin can reduce oxygen-transfer efficiency. Membrane plants lean toward non-silicone products to protect the MBR. See defoamers in wastewater treatment and the water treatment hub.

Fermentation and bioprocess

CO2 evolution plus proteins in the wort, mash, or media builds foam that steals headspace and fouls vents. Silicone gives the fastest knockdown at the lowest dose, so a food-grade emulsion or simethicone compound is the default for breweries, distilleries, and fuel-ethanol plants. Where the product passes through ultrafiltration or a perfusion membrane, silicone persistence becomes a fouling cost and a polyether may win even at a higher dose. Control it off a foam probe, never a fixed standing dose. Details in fermentation antifoam selection.

Coatings, adhesives, and latex

Waterborne paint, adhesive, and latex lines fold air in at the grind and at fill. A fine-droplet silicone emulsion clears that foam; the same incompatibility that breaks the bubble craters the film past the dosing window. Formulators split the dose between grind and let-down and read defects by drawdown as they ladder up. High-gloss and multi-coat systems often want a silicone-polyether or non-silicone grade instead. See defoamer for water-based coatings and the coatings hub.

Textile dyeing and wet processing

Jet dyeing, scouring, and print pastes foam under high shear at bath temperature, and foam in a jet machine means uneven dyeing and pump cavitation. The buying criterion is emulsion stability, not raw potency. An emulsion that breaks under the shear and heat of the bath deposits silicone on the fabric as spots that show after dyeing. Specify a shear-stable, high-temperature grade, check it against the actual dye bath before scaling, and dose at the point of turbulence.

Pulp and paper

Paper machine wet ends, coating kitchens, and mill effluent respond well to silicone emulsions at ppm, and the industrial grade in the RawSource line is built for that persistent foam. Hot, high-pH brownstock washing is the exception. Kraft alkaline service disfavors silicone as the workhorse, and mills usually run an EO/PO polyether with a cloud point tuned to the washer temperature. Ask for both when the duty spans the mill, and check deposit behavior on felts and wires during the trial.

Oil, gas, and refining

Drilling fluid takes a compound or emulsion chosen for compatibility with the mud system. Amine gas-treating units are the caution case: silicone is potent there and also fouls reboilers, exchangers, and cartridge filters, so a polyether is often the better long-run choice. High-temperature duty such as refinery delayed cokers uses a high-viscosity neat PDMS fluid, and the 60,000 cSt silicone oil is stocked for that service. The oil and gas hub covers the adjacent oilfield chemistry.

Food processing

Vegetable wash water, fryers, sugar processing, and beverage lines run food-grade silicone antifoam. Under 21 CFR 173.340, dimethylpolysiloxane used as a defoaming agent in food processing is limited to 10 ppm in finished food, with zero permitted in milk. That is a residue cap, not a removal mandate, so the dose is still set at the minimum that controls the foam.

The RawSource food-grade line is formulated to that section; confirm the documentation for your product and jurisdiction. Adjacent processing aids sit on the food and beverage hub.

Bulk supply, grades, and quality control

One desk covers the silicone foam-control range, so a buyer running wastewater, a coatings line, and a food plant needs one supplier.

Typical values — Certificate of Analysis governs. The CoA for the lot you buy is the specification; anything quoted here or on a product page is orientation.

What the CoA reports on an emulsion, and why it matters when you compare quotes:

For the food-grade line the regulation also defines the PDMS: viscosity 300 to 1,050 centistokes at 25 C, no more than 18 percent weight loss after four hours at 200 C, refractive index 1.400 to 1.404, and any formaldehyde preservative at no more than 1.0 percent of the PDMS content, per 21 CFR 173.340. Typical values — Certificate of Analysis governs.

Packaging runs pails for trials, drums for steady consumption, and IBC totes for high-volume duty, with net weights confirmed on the quote. Emulsions are water-continuous: keep them from freezing, store sealed out of direct sun, and roll or stir a drum that has stood for months before drawing from it, because a separated emulsion doses unevenly. Neat fluids and compounds are far more forgiving in storage.

How to request a quote

Send five things and we can quote accurately and recommend a grade:

1. The system, not just the product. What is foaming, at what temperature and pH, and what sits downstream (membranes, filters, a topcoat, a food product)? 2. Form and active you run today, or the duty if you have no working product. 3. Volume and reorder rhythm, so we quote pails, drums, or totes at the right cadence. 4. Compliance requirements, such as food-grade documentation under 21 CFR 173.340. 5. Delivery location and any packaging constraints at the dock.

Unsure of the grade? Describe the foam and we start from the table above and send a sample. The cheapest way to de-risk a tote is a bottle test on your own liquid before the first drum ships. Buyers sourcing the wider silicone range can start at the bulk silicone supplier page.

Methodology and sources

Chemical identity is anchored to the PubChem records for PDMS (CAS 63148-62-9) and simethicone (CAS 8050-81-5). Every regulatory number is taken from 21 CFR 173.340 on eCFR. Product forms, active percentages, and grade lines reflect the RawSource catalog at the time of writing. Per-system starting doses live in the defoamer dosing guide and the complete guide to defoamers. Typical values are not a guaranteed specification; the CoA and current Safety Data Sheet (SDS) govern.

Frequently asked questions

What is the difference between a silicone antifoam and a silicone defoamer? The industry uses the terms loosely for the same PDMS-silica products. Strictly, an antifoam is dosed ahead of time to prevent foam and a defoamer knocks down foam that already exists. Most silicone emulsions do both; the grade you buy is decided by the system, not the label.

Should I buy a 10% active emulsion or a 100% compound? Buy on cost per pound of active silicone. A 10% emulsion is ready to dose and tolerant of rough handling, which suits a small line or a day tank. A 30 to 50% concentrate ships less water per pound of active but needs on-site dilution. If you can dilute reliably, the concentrate is usually the better buy.

Is an “organic silicon defoamer” the same thing as a silicone defoamer? Yes. “Organic silicon” and “organosilicone” are translations of the same chemistry: polydimethylsiloxane, an organic-substituted silicon polymer, formulated with hydrophobic silica. A specification that calls for an organic silicon defoamer means a PDMS-based silicone antifoam emulsion or compound.

What defoamer is used for wastewater treatment? For surfactant and chemical foam in aeration basins, DAF units, and digesters, a silicone antifoam emulsion spot-dosed at the foam surface is the standard answer because it works at ppm. For filamentous biological foam it only treats the symptom, and membrane bioreactors often run a non-silicone product to limit fouling. Set the dose by bottle test.

Is silicone antifoam food grade? A specific food-grade line is; a general industrial emulsion is not. Under 21 CFR 173.340, dimethylpolysiloxane may be used as a defoaming agent in food processing at up to 10 ppm in finished food, with zero permitted in milk, and the PDMS must meet the viscosity, heating-loss, and refractive-index limits in that section. Buy the food-grade line with its documentation and confirm suitability for your product.

How is silicone antifoam packaged and stored? In pails, drums, and IBC totes, with net weights confirmed on the quote and a CoA on every lot. Keep emulsions from freezing and out of direct sun, store them sealed, and roll or stir a drum after long standing. Neat PDMS fluids and 100% compounds are more forgiving in storage.

Editorial note. This article is general procurement and technical reference for industrial and professional buyers and is not safety, regulatory, or treatment advice. Product forms, active levels, and grade lines describe the RawSource catalog at the time of writing; regulatory limits are quoted from 21 CFR 173.340 and must be confirmed for your product, process, and jurisdiction. Typical values are not a guaranteed specification; the Certificate of Analysis governs the material you buy. Always consult the current Safety Data Sheet (SDS) before handling. Products are for industrial and professional use only. RawSource makes no warranty, express or implied, and assumes no liability for use of this information.