Product Overview
Hydrofluorosilicic Acid 23% (HFS) is a technical-grade aqueous solution of fluorosilicic acid, CAS 16961-83-4. It is a colorless fuming liquid with a sour, pungent odor, and it is corrosive to metals and tissue. Municipal and industrial buyers order it as a fluoride source for water fluoridation, as a precursor in chemical synthesis of fluorinated compounds, and for pH adjustment, electroplating, and related metal-finishing work. This is a working industrial acid, not a food or pharmaceutical material, and it demands the same respect at the receiving dock that we give it on our own loading dock in Taylor, Texas.
We offer it in pack sizes from 1 quart bottles through 5 and 15 gallon carboys, 55 gallon drums, and 275 and 330 gal totes — a range that covers bench evaluation through continuous-feed plant service. All sizes are offered to order.
Why This Concentration
The 23% concentration is the workhorse strength for fluoridation feed and general industrial use. It delivers enough fluoride per gallon that metering volumes stay practical at a treatment plant, while remaining an aqueous solution a trained operator can transfer with standard corrosion-resistant pumps and HDPE-compatible plumbing. A stronger acid would shift more handling burden onto your team for little process gain in most feed applications; a dilute solution would force you to buy, freight, and store more water.
The trade-off is real: at 23% this is still a fuming, Packing Group II corrosive (per 49 CFR 172.101). Both the fumes and very brief liquid contact can cause severe, painful burns. Pick this concentration when your process needs a dependable fluoride ion source and your facility already runs corrosive-liquid procedures — secondary containment, compatible transfer equipment, and operators trained on acid handling. If you only need trace fluoride at bench scale, start with a quart and work up.
Chemical Profile
Fluorosilicic acid, formula H2SiF6, molecular weight 144.091, CAS 16961-83-4. As supplied, the 23% solution is a colorless fuming liquid with a penetrating, pungent odor — the odor alone tells an operator the container is open before any instrument does. Published density is 1.19 for the 23% w/w aqueous solution at 20 °C, so a 55 gallon drum of this acid is meaningfully heavier than the same drum of water; plan your drum-handling equipment accordingly. The product is corrosive to metals (per the product's GHS classification), which is why HDPE and other compatible plastics — not steel — are the right containment for storage and transfer.
Industrial Applications
Buyers put this acid to work in a handful of well-established roles:
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Water fluoridation — the dominant use. HFS is metered into municipal drinking water as a fluoride ion source in community fluoridation programs.
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Chemical synthesis — serves as a fluorine-bearing precursor in the synthesis of fluorinated compounds and fluorosilicates.
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pH adjustment — used in water treatment and environmental management where an acid feed is needed to bring pH down.
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Electroplating and metal finishing — incorporated into plating baths where its chemistry supports adhesion and finish quality.
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Cement, ceramics, and wood treatment — used in hardening cement and ceramics and as a wood preservative.
In each case the acid's job is the same: deliver fluoride or acidity into the process stream in a controlled, meterable liquid form. Dosing rates, bath formulations, and treatment targets are process-specific — set them from your own process data and the technical data sheet, not from a product page.
Handling & Storage
The signal word is Danger (per the product's GHS classification). The classification carries H290 May be corrosive to metals, H302 Harmful if swallowed, H312 Harmful in contact with skin, H314 Causes severe skin burns and eye damage, and H332 Harmful if inhaled (per the product's GHS classification). Treat every transfer as a splash and vapor exposure risk: acid-resistant gloves, sealed goggles or a face shield, and chemical-resistant clothing, with adequate ventilation at the point of use.
Store it cool and dry, out of direct sunlight, in HDPE containers — never in unlined metal, which the acid will attack. Keep it segregated from strong bases and oxidizing agents. Have neutralization and spill procedures written and staged before the first container arrives, not after. These are the same rules our warehouse team follows when packing this acid for outbound freight, and the shipping and handling guidance on this page is reviewed by Andre Taki, DOT Hazmat Specialist.
Hazmat & Shipping
This product ships as regulated hazardous material under the proper shipping name Fluorosilicic acid, UN1778 (per 49 CFR 172.101). It is Hazard Class 8, corrosive, with no subsidiary hazard (per 49 CFR 172.101), and is assigned Packing Group II (per 49 CFR 172.101). Every order leaves our dock with hazmat-compliant packaging, marking, and labeling for that classification. Confirm carrier fees, routing, and your site's receiving requirements with your Alliance Chemical representative before ordering drum or tote quantities — hazmat freight logistics vary by destination.
Documentation
A Safety Data Sheet ships with every order and is available in English, Spanish, French, and Japanese. A technical data sheet is available for spec review before you buy, and a lot-specific Certificate of Analysis is available with your shipment so your QC records trace back to the exact lot you received.
Why Buy from Alliance Chemical
Few suppliers will sell UN1778 Class 8 corrosive in every size from a 1 quart bottle to a 330 gal tote with SDS, TDS, and lot-specific COA support behind each shipment — that range lets a plant trial the acid at bench scale and scale to bulk without changing suppliers. Alliance Chemical has operated as an industrial chemical distributor since 1998, and we pack and ship from our warehouse at 204 S Edmond St, Taylor, Texas. Our expertise is distribution: correct DOT classification, compatible packaging, and documentation that lets a buyer decide fast and receive without surprises. Handling and shipping guidance on this page is reviewed by Andre Taki, DOT Hazmat Specialist.
