What Is Boric Acid 99.5%?
Boric acid (H₃BO₃), also known as orthoboric acid, hydrogen borate, or boracic acid, is a naturally occurring, mildly acidic inorganic compound derived from the element boron. The “99.5%” designation signifies its purity level — meaning at least 99.5% of the compound is pure boric acid, with only trace impurities permitted.
According to the National Center for Biotechnology Information (PubChem), boric acid has been commercially produced and used for over a century, remaining one of the most functionally versatile inorganic compounds in modern manufacturing. It presents as a white crystalline powder or colorless flaky crystals — odorless, water-soluble, and thermally stable below its decomposition point.
Whether you are a procurement specialist evaluating chemical suppliers, a formulation scientist optimizing product quality, or an industrial buyer managing raw material compliance, understanding the full profile of Boric Acid 99.5% is essential. For foundational reference on boron chemistry, the Royal Society of Chemistry’s Periodic Table provides authoritative elemental data.
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02
Chemical Properties & Specifications1
The physicochemical profile of Boric Acid 99.5% underpins its broad utility. Full regulatory chemical identity is documented by the European Chemicals Agency (ECHA), the authoritative EU reference for REACH-registered substances.
Chemical NameBoric Acid / Orthoboric Acid
Molecular FormulaH₃BO₃
Molecular Weight61.83 g/mol
CAS Number10043-35-3
Purity (minimum)99.5%
AppearanceWhite crystalline powder / flakes
Melting Point170.9 °C (339.6 °F)
Boiling Point300 °C — decomposes
Density1.435 g/cm³
Water Solubility57 g/L at 25 °C
pH (0.1 M solution)~5.1 (weakly acidic)
Flash PointNon-flammable
Analytical Characteristics
At 99.5% purity, boric acid yields consistent infrared (IR) spectral signatures and passes atomic absorption spectroscopy (AAS) for heavy metal limits, ion chromatography for sulfate/chloride content, and gravimetric assay for purity confirmation. Standard test methods are maintained by ASTM International, the globally recognised body for chemical testing standards.
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See Section 09 for the full Certificate of Analysis (CoA) parameter checklist when sourcing from suppliers.
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Why Purity Matters: 99.5% vs. Lower Grades
Not all boric acid is equivalent. Purity grade directly governs product performance, regulatory eligibility, and safety outcomes across every sector where it is used.
Recommended
99.5% Grade
- Meets USP, EP, BP pharmacopoeia standards
- Heavy metals <10 ppm lead
- Arsenic <1 ppm
- Pharma, cosmetics, electronics-ready
- Consistent batch-to-batch quality
- Search for certified boric acid suppliers https://www.criticalindustrialchemicals.com/product/boric-acid/
98% Technical
- Higher sulfate & chloride impurities
- Suitable for bulk glass/fibre production
- Not fit for pharma/food contact
- Lower regulatory compliance
- Find verified manufacturers and exporters of 98% Technical Grade Boric Acid on https://www.criticalindustrialchemicals.com/inorganic-acids/
<95% Industrial
- Significant impurity levels
- Risk of process contamination
- Heavy industrial use only
- Restricted regulatory status
- Search for certified boric acid suppliers
Pharmacopoeial compliance is verified through the U.S. Pharmacopeia (USP), whose published monographs define the minimum acceptable standards for boric acid in human-use products. Impurities at even sub-1% levels can catalyse unwanted reactions, alter product colour, or cause regulatory non-compliance.
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See Section-Regulatory 08 Compliance for how purity classification affects REACH, FDA, and CLP regulatory status by jurisdiction.
04
Key Industrial & Commercial Applications
Boric Acid 99.5% is a cornerstone raw material across a remarkably diverse range of industries, valued for its mild acidity, heat resistance, water solubility, and precise boron content.
Search for suppliers with ISO 9001 certification, GMP certification, or other relevant industry standards. https://www.criticalindustrialchemicals.com/product/boric-acid/
Glass & Fiberglass Manufacturing
The glass industry is among the largest global consumers of boric acid. It functions as a flux and network-former in borosilicate glass production — used in laboratory glassware, pharmaceutical primary packaging, optical instruments, and heat-resistant cookware. In fiberglass manufacturing, it lowers the batch melting point, improves melt viscosity, and enhances chemical durability. At 99.5% purity, it ensures colour neutrality and consistent refractive indices — both critical in optical and pharmaceutical-grade glass.
Electronics & Semiconductors
In electrolytic capacitor manufacture, boric acid stabilises electrolyte pH and prevents aluminium oxide layer degradation. Semiconductor fabrication demands electronic-grade chemical purity to eliminate ionic contaminants that compromise circuit performance. It also cross-links polyvinyl alcohol (PVA) films used in LCD polarisers. Peer-reviewed materials research on electronic-grade chemical purity is accessible through IEEE Xplore.
Wood Preservation & Flame Retardants
Boric acid and its sodium salts are widely employed as low-toxicity wood preservatives against fungi, termites, and wood-boring beetles — and as flame retardants in cellulose insulation, textiles, and polymer composites. Industry treatment standards are maintained by the American Wood Protection Association (AWPA).
Ceramics & Glazes
As a flux in ceramic glaze formulations, boric acid reduces the melting temperature of silicates, improves surface smoothness, and enhances chemical resistance. At 99.5% purity, it delivers predictable glaze melt behaviour and batch-to-batch consistency in high-volume ceramic production.
Welding, Metallurgy & Electroplating
Boric acid dissolves metal oxides in welding flux applications, preventing oxidation at high temperatures for cleaner welds. In nickel electroplating baths, it acts as a critical pH buffer, preventing hydrogen pitting and producing bright, smooth deposits. Electroplating industry specifications are upheld by the National Association for Surface Finishing (NASF). The 99.5% grade is mandatory in plating applications to avoid ionic contamination in bath chemistry.
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See Section 05 — Agricultural Uses and Section 06 — Pharmaceutical Applications for sector-specific guidance beyond industrial use.
05
Agricultural Uses of Boric Acid 99.5%
Boron is an essential micronutrient for plant physiology — critical for cell wall formation, sugar transport, and reproductive development. Boric acid is the primary plant-available boron source in commercial agriculture. The Food and Agriculture Organization of the United Nations (FAO) recognises boron as a key micronutrient in sustainable soil fertility management.
Foliar Application & Soil Amendment
Boron deficiency causes hollow heart in beets, hollow stem in broccoli, poor fruit set, and reduced pollination efficiency. Boric acid 99.5% is formulated into foliar sprays and soil drenches for crops including broccoli, cauliflower, apples, grapes, almonds, sunflower, cotton, and alfalfa. High purity is critical — the agronomic window between boron sufficiency and phytotoxicity is narrow, and impure formulations can deliver inconsistent dosing.
Pest Control & Insecticide Formulations
Boric acid is a registered pesticide active ingredient in many jurisdictions. It disrupts insect digestive systems and is effective against cockroaches, ants, silverfish, and termites. Pesticide registration data and approved application rates are maintained by the U.S. Environmental Protection Agency (EPA).
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When applying boric acid in field conditions, refer to Section 07 — Safe Handling & Storage for appropriate PPE requirements and application precautions.
06
Pharmaceutical & Medical Applications
Boric acid has a well-documented history in medicine. Pharmacopoeial monographs are published by the U.S. Pharmacopeia (USP) and the European Medicines Agency (EMA), defining purity, testing methods, and permitted uses for pharmaceutical-grade material. Search for certified ISO 9001, GMP ,Pharmaceutical & Medical (USP) Grade suppliers https://www.criticalindustrialchemicals.com/product/boric-acid/
Antiseptic & Antifungal Formulations
| Application | Use / Mechanism | Grade Required |
|---|---|---|
| Ophthalmic Eye Drops & Eyewash | Mild antiseptic; pH buffer to match tear fluid | USP / EP |
| Vaginal Suppositories | Recurrent vulvovaginal candidiasis & BV treatment | USP 99.5% |
| Ear Drops (Otitis Externa) | Antifungal & antibacterial in external ear canal | EP / BP |
| Wound Care Solutions | Dilute antiseptic for minor wounds (historical) | Technical / USP |
| Cosmetics & Personal Care | pH adjuster, preservative booster, antiseptic | USP 99.5% |
Clinical evidence for boric acid in gynaecological applications — including its use as a second-line treatment for recurrent bacterial vaginosis — is reviewed in guidelines published by the Centers for Disease Control and Prevention (CDC). Permitted cosmetic concentrations in the EU are governed by the European Commission Cosmetics Regulation.
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When sourcing boric acid for pharmaceutical or cosmetic use, consult Section 09 — Buying Guide for USP/EP grade certification requirements and GMP supplier criteria. Search for Approved Pharmaceutical & Medical (USP) Grade 99.5% Boric Acid suppliers https://www.criticalindustrialchemicals.com/product/boric-acid/
07
Safe Handling & Storage of Boric Acid 99.5%
While classified as low in acute toxicity, boric acid requires disciplined handling protocols — particularly at industrial volumes. Comprehensive occupational health guidance is published by the National Institute for Occupational Safety and Health (NIOSH). Contact Major Chemical Distributors prioritized safe handlind & Storage of Boric Acid 99.5% https://www.criticalindustrialchemicals.com/
Personal Protective Equipment (PPE)
| Body Area | Minimum PPE Requirement |
|---|---|
| Eyes / Face | Safety goggles or full face shield; splash goggles for liquid contact |
| Skin / Hands | Nitrile or neoprene gloves; long-sleeved chemical-resistant clothing |
| Respiratory | N95 dust respirator when handling powder in open environments |
| Feet / Body | Chemical-resistant boots; impervious apron in bulk handling areas |
Storage Requirements
| Parameter | Specification |
|---|---|
| Temperature | 15 – 30 °C (59 – 86 °F), ambient controlled |
| Humidity | Low humidity; sealed containers essential |
| Container Materials | HDPE, polypropylene, or 316 stainless steel |
| Incompatibles | Strong bases (NaOH), potassium metal, strong oxidisers |
| Shelf Life | 2 – 5 years in properly sealed, dry conditions |
| Segregation | Store separately from food, animal feed, and medicinal products |
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For GHS/CLP classification details and occupational exposure limits, see Section 08 — Safety Data & Regulatory Compliance
08
Safety Data & Regulatory Compliance
Full toxicological profiles for boric acid are maintained by the Agency for Toxic Substances & Disease Registry (ATSDR), a division of the U.S. Department of Health and Human Services.
Key Toxicological Data
| Parameter | Value / Classification |
|---|---|
| Oral LD50 (rat) | ~2,660 mg/kg — comparable to table salt |
| Dermal Absorption | Negligible through intact skin; significant through broken skin |
| Reproductive Toxicity | EU CLP Cat. 1B — H360FD (high-dose animal data) |
| Carcinogenicity | Not classified (IARC, NTP, ACGIH) |
| Aquatic Toxicity | Low; not classified as environmentally hazardous |
Regulatory Status by Region
| Region | Regulatory Framework | Current Status |
|---|---|---|
| USA | TSCA, EPA, FDA | Approved; registered pesticide; USP grade for pharma |
| European Union | REACH, CLP | SVHC candidate (reproductive concerns); authorisation pathway |
| China | GB Standards / MEE | Permitted for industrial and agricultural applications |
| India | BIS / CPCB / Insecticides Act | Permitted; regulated as registered pesticide |
| Australia | AICIS (formerly NICNAS) | Approved for industrial and consumer product use |
Occupational Exposure Limits (OELs)
REACH compliance documentation is available through the ECHA REACH Registration portal. For U.S. workplace safety requirements, current chemical hazard standards are maintained by OSHA Chemical Hazards (PEL guidelines) and ACGIH (TLV-TWA: 2 mg/m³, inhalable fraction).
09
Buying Guide: Sourcing Boric Acid 99.5%
Sourcing high-quality Boric Acid 99.5% requires systematic evaluation of suppliers against documented quality, regulatory, and logistical criteria.
Look for Boric Acid Suppliers and Distributors with Codex, ISO 9001, GMP, or Pharmacopeia , European / British Pharmacopeia certification https://www.criticalindustrialchemicals.com/product/boric-acid/
Certificate of Analysis (CoA) — Key Parameters
| Parameter | Specification (Min/Max) |
|---|---|
| Assay (Purity) | ≥ 99.5% |
| Sulfate (SO₄) | ≤ 0.01% |
| Chloride (Cl) | ≤ 0.005% |
| Heavy Metals (as Pb) | ≤ 10 ppm |
| Iron (Fe) | ≤ 10 ppm |
| Arsenic (As) | ≤ 1 ppm |
| Moisture | ≤ 0.5% |
Grade Certifications Required by Application
| Grade | Standard Body | Applications |
|---|---|---|
| USP Grade | U.S. Pharmacopeia | Pharmaceutical, ophthalmic, medical devices |
| EP / BP Grade | European / British Pharmacopeia | EU pharmaceutical and cosmetic products |
| FCC Grade | Food Chemicals Codex | Food-contact packaging, processing aids |
| Technical Grade | ISO / Customer Spec | Industrial glass, ceramics, electroplating |
Supplier Qualification Checklist
Qualified suppliers should hold ISO 9001:2015 quality management certification, provide REACH-compliant Safety Data Sheets, maintain GMP certification for pharmaceutical supply, and offer third-party laboratory testing with full traceability. Request auditable documentation of raw borate sourcing and supply chain continuity.
↪ Internal Reference
Review Section 02 — Chemical Specifications and Section 03 — Purity Comparison when validating CoA parameters against your application requirements.
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Frequently Asked Questions
Is Boric Acid 99.5% the same as borax?
No. Boric acid (H₃BO₃) and borax (sodium tetraborate, Na₂B₄O₇·10H₂O) are chemically distinct compounds. Borax is the sodium salt of boric acid. They differ in pH, solubility, and regulatory status. See the PubChem entry for borax for a side-by-side chemical profile.
Can Boric Acid 99.5% be used in food applications?
Boric acid is not approved as a food additive in the USA, EU, or most jurisdictions. Limited traditional use exists in some Southeast Asian countries under local regulation. Consult the FDA Food Additives Status List for current U.S. regulatory guidance.
What is the difference between technical grade and pharmaceutical grade?
Technical grade contains elevated impurities (sulfates, chlorides, heavy metals) suitable for industrial processes. Pharmaceutical (USP/EP) grade meets strict purity and testing limits for human-use products manufactured under GMP conditions. See Section 03 for a complete grade comparison.
How should boric acid waste be disposed of?
Dilute aqueous solutions can typically be neutralised and directed to permitted wastewater treatment. Concentrated or large-volume waste requires licensed hazardous waste contractors. The EPA Hazardous Waste Management guidelines provide jurisdiction-specific disposal protocols.
Is Boric Acid 99.5% classified as a dangerous good for transport?
In most formulations, boric acid is not classified as a dangerous good under IATA, IMDG, or ADR regulations. However, national regulations may vary. Always confirm with your freight forwarder and provide the current SDS. Refer to Section 07 for storage and handling context.
What is the shelf life when properly stored?
Boric acid 99.5% retains its purity for 2–5 years when stored sealed in dry conditions at 15–30 °C. Moisture exposure can cause caking but does not typically degrade chemical purity — material can be re-dried and re-sieved. See Section 07 — Storage Requirement for full protocol.