Sodium Hydroxide Flakes CAS 1310-73-2: Properties, Grades, Applications and Supplier Guide

The modern industrial landscape relies heavily on foundational chemicals to drive manufacturing, synthesis, and processing operations. Among these essential building blocks, solid caustic soda stands out as one of the most versatile and highly demanded strong bases in the world. As an extremely potent alkali, it is a critical raw material utilized across sectors ranging from water treatment and petrochemical refining to textile manufacturing and daily hygiene product formulation.

Often universally identified in regulatory databases and shipping manifests by its specific chemical registry code, CAS 1310-73-2, this white, highly corrosive crystalline solid is predominantly manufactured via the chlor-alkali process. In this state-of-the-art electrochemical method, sodium chloride brine is electrolyzed to yield chlorine gas, hydrogen gas, and aqueous liquid caustic soda. To create the dry form, this liquid is evaporated at extremely high temperatures until a molten state is achieved, which is then passed over cooled flaking drums. The resulting product is a flat, easily dissolvable, dry alkali fragment that offers distinct logistical and operational advantages over its liquid counterpart, particularly in long-distance freight and precise batch-formulation scenarios.

Chemical Characteristics and Physical Properties

Understanding the fundamental physical and chemical Properties of this compound is crucial for chemical engineers, plant operators, and procurement specialists. In its pure, dry state, the substance is an odorless, white crystalline material. It is inherently hygroscopic, meaning it possesses a remarkable affinity for moisture. If left exposed to ambient air, it will rapidly absorb atmospheric water vapor, eventually dissolving into an aqueous pool—a phenomenon known as deliquescence. Furthermore, it readily absorbs carbon dioxide from the air to form sodium carbonate, which is why it must always be stored in hermetically sealed, moisture-proof containers.

One of the most defining behavioral traits of this alkali is its highly exothermic dissolution process. When the dry solid is added to water, the disruption of its ionic lattice and the subsequent hydration of sodium and hydroxide ions release an immense amount of thermal energy. If not managed properly, this heat can rapidly boil localized pockets of water, causing violent splattering of a highly corrosive solution. Therefore, standard operating procedures dictate that the solid must always be added slowly to water with continuous agitation; water should never be poured directly onto the bulk solid.

Below is a detailed breakdown of the fundamental specifications and physical attributes of the dry alkali:

From a logistical standpoint, the dry form presents zero vapor pressure under normal environmental conditions, eliminating the risk of inhalation exposure to gaseous fumes during standard storage. Furthermore, unlike solutions that can freeze or crystallize during winter transit, the solid format is impervious to cold-weather logistical disruptions, making it an ideal choice for facilities located in temperate or extreme northern and southern climates.

Purity Standards and Quality Grades

Chemical manufacturers do not produce a single, uniform type of this alkali. Because it is utilized in everything from heavy industrial mining to delicate pharmaceutical synthesis, the manufacturing process is tailored to yield different purity classifications. Selecting the correct quality tier is essential for balancing operational efficiency with procurement budgets. There are three primary Grades that dominate the international market, each tailored to specific tolerances for impurities such as iron, heavy metals, and residual chlorides.

Technical Tier

The technical tier is the standard workhorse of the heavy manufacturing sector. Typically offering an assay of 98% to 99% purity, this classification is optimized for cost-effectiveness rather than absolute chemical perfection. It may contain trace amounts of sodium chloride, sodium carbonate, and minute parts-per-million (ppm) of iron. Because these impurities do not interfere with heavy industrial reactions, this tier is exclusively selected for water neutralization, heavy degreasing, paper bleaching, and large-scale alumina processing. It is the most economical and widely traded tier globally.

Food and Pharmaceutical Tier (FCC / USP)

For processes where the alkali will come into direct or indirect contact with consumable goods, a highly regulated tier is required. Food Chemical Codex (FCC) or United States Pharmacopeia (USP) standard materials undergo rigorous secondary purification to strip away heavy metals, mercury, and arsenic to barely detectable levels. This classification guarantees an assay of at least 99% with strict limits on contaminants. It is heavily utilized in food processing (such as cocoa processing, caramel coloring, and poultry scalding), municipal drinking water purification, and as a pH-adjusting excipient in pharmaceutical manufacturing.

Rayon Tier (High-Purity)

Historically developed for the delicate process of manufacturing synthetic rayon fibers, this specific classification requires an exceptionally low iron and copper content. Even trace amounts of these transition metals can discolor textile fibers or catalyze unwanted degradation of cellulose chains. While modern membrane-cell electrolysis has naturally lowered iron content across all outputs, specific rayon-tier products are still requested by high-end textile manufacturers, semiconductor facilities, and precision laboratory reagent suppliers.

Industrial Implementations and Key Applications

The sheer versatility of this strong base cannot be overstated. It acts as a primary chemical intermediate, a neutralizing agent, and a potent solvent for organic matter. The diverse Applications for this chemical span across both traditional heavy industries and cutting-edge technological sectors. Below is a comprehensive analysis of the major sectors heavily reliant on this dry chemical base.

Saponification: Soap and Detergent Manufacturing

Perhaps the oldest and most famous use of this alkali is in the creation of hard bar soaps and commercial detergents. Through a chemical reaction known as saponification, the strong base cleaves the ester bonds of triglycerides (fats and oils, such as tallow, coconut oil, or olive oil). This hydrolysis reaction yields two vital products: glycerol (a valuable humectant) and fatty acid salts, which constitute the soap itself. The dry solid is preferred by both artisanal cold-process soap makers and continuous-process commercial detergent manufacturers because it allows for exact formulation control without the added water weight of pre-mixed solutions.

Water and Wastewater Treatment

Environmental compliance requires municipal and industrial facilities to stringently control the pH of their effluent discharges. Acidic wastewater—often generated by mining operations, metal plating, and chemical synthesis—must be neutralized before it can be safely released into public waterways. Adding precise doses of dissolved alkali rapidly raises the pH to a neutral 7.0. Furthermore, in heavy metal remediation, raising the pH forces toxic dissolved metals (like lead, copper, and zinc) to precipitate out of the solution as solid metal hydroxides, which can then be easily filtered and removed from the water supply.

Alumina Refining (The Bayer Process)

The global aluminum industry is one of the largest single consumers of this caustic substance. Aluminum is extracted from bauxite ore via the Bayer process. The crushed bauxite is digested in a highly concentrated, pressurized, and boiling bath of the alkali. The base selectively dissolves the aluminum oxide to form sodium aluminate, while leaving behind insoluble impurities known as “red mud” (primarily iron oxides and silica). Without this crucial digestion step, modern aluminum production would be chemically and economically impossible.

Pulp and Paper Manufacturing

In the Kraft process, wood chips are converted into high-strength paper pulp. The wood fibers are bound together by a complex organic polymer called lignin. To separate the usable cellulose fibers from the lignin, the wood is cooked in “white liquor”—a highly alkaline solution composed of sodium sulfide and our focal chemical base. The strong alkali breaks down the lignin’s molecular structure, allowing it to be washed away. Later in the process, the base is also utilized in the bleaching stages to extract residual lignin and brighten the final paper product.

Textile Mercerization

In the textile industry, cotton fibers are often treated with a concentrated alkaline bath in a process called mercerization. The strong base causes the flat, ribbon-like cotton fibers to swell and become cylindrical. This permanent structural alteration dramatically increases the fiber’s tensile strength, gives it a smooth, silk-like luster, and significantly improves its ability to absorb commercial dyes, resulting in much deeper and more vibrant fabric colors.

Safety, Handling, and Environmental Regulations

Because of its extreme alkalinity, this substance is classified as a hazardous material under global transportation and occupational safety frameworks. It operates under UN Number 1823 and is universally recognized as a Class 8 Corrosive substance. Handling this material requires strict adherence to safety protocols to prevent catastrophic injury and environmental damage.

Occupational Hazards and Personal Protective Equipment (PPE)

The solid form and its concentrated solutions cause severe, irreversible chemical burns upon contact with living tissue. Unlike acidic burns, which often coagulate proteins and form a barrier, alkaline burns cause liquefactive necrosis. This means the chemical continues to deeply penetrate and destroy tissue, dissolving fats and proteins, until it is entirely neutralized or washed away. Eye contact is particularly dangerous and can lead to permanent blindness within seconds.

Operators must wear comprehensive PPE when handling the dry chemical or mixing solutions. This includes:

• Chemical-splash goggles and full-face shields to prevent ocular exposure.
• Alkali-resistant heavy nitrile or neoprene gloves extending up the forearm.
• Corrosive-resistant aprons or full Tyvek suits.
• NIOSH-approved respirators equipped with particulate filters if there is any risk of airborne dust generation during the transfer of the dry material.

First Aid and Spill Response

In the event of skin or eye contact, the immediate and most critical first aid response is continuous flushing with copious amounts of clean water for a minimum of 15 to 30 minutes. Medical attention must be sought immediately. Emesis (vomiting) should never be induced if the substance is swallowed, as this will burn the esophagus a second time; instead, the victim should drink small amounts of water or milk to dilute the base, provided they are conscious.

Spills of the dry solid should be carefully swept or vacuumed up using non-sparking tools, ensuring no dust is raised. If the material has become wet or has formed a localized puddle, it must be cautiously neutralized using a mild acid—such as dilute acetic acid (vinegar) or citric acid—before being absorbed with inert materials like sand or vermiculite. It must never be flushed into local sewers without prior neutralization, as it will destroy aquatic ecosystems by radically spiking the pH of natural water bodies.

Procurement Strategy and Supplier Guide

Navigating the global chemical supply chain requires an understanding of market dynamics, freight logistics, and stringent quality assurance. Welcome to the definitive Supplier Guide for chemical procurement managers looking to optimize their sourcing strategy. The global market for this commodity is heavily influenced by the supply and demand of its co-product, chlorine. Because the two are produced in a fixed ratio, a slump in PVC manufacturing (which uses chlorine) can throttle the production of the alkali, driving up global prices.

When sourcing Sodium Hydroxide Flakes at an industrial scale, several factors dictate the final landed cost and operational success of the transaction:

1. Market Pricing and Freight

As of late 2026, global pricing structures remain highly dependent on origin ports and ocean freight rates. FOB (Free on Board) prices from major export hubs in the Middle East (such as Jebel Ali) and Turkey (such as Mersin) typically range between $780 and $800 per Metric Ton (MT) for standard 98% technical quality. Because the dry product contains virtually no water, buyers are not paying to ship “dead weight,” making it vastly more economical for international, long-distance freight compared to 50% liquid solutions. However, buyers must factor in the Class 8 Dangerous Goods surcharge levied by ocean carriers, which typically adds a 15% to 30% premium onto standard container freight rates.

2. Packaging and Moisture Defense

The extreme hygroscopy of the product dictates how it must be packaged. Standard industrial packaging consists of 25-kilogram woven Polypropylene (PP) bags equipped with thick, heat-sealed inner Polyethylene (PE) liners. For massive operations, 1 Metric Ton FIBC (Flexible Intermediate Bulk Container) “jumbo bags” are utilized. When evaluating a vendor, procurement teams must ensure that the packaging guarantees a hermetic seal. If the inner PE liner is compromised during transit, the material will absorb humidity, causing the separate dry fragments to fuse into a massive, rock-hard block that is completely unusable in automated hopper systems.

3. Quality Assurance and Documentation

Before executing a purchase order, buyers must request a recent Certificate of Analysis (CoA) from the vendor’s specific batch lot. The CoA will verify the exact assay percentage, the maximum threshold of sodium carbonate, and the iron content (measured in ppm). Additionally, a legally compliant Safety Data Sheet (SDS / MSDS) matching the destination country’s GHS (Globally Harmonized System) requirements must be provided by the manufacturer to ensure smooth customs clearance and regulatory compliance at the receiving facility.

Preguntas frecuentes

1. How should the solid material be stored to prevent clumping and degradation?

It must be stored in a cool, dry, and well-ventilated area away from direct sunlight and incompatible materials like strong acids or reactive metals (aluminum, zinc). Ensure the original packaging remains tightly sealed; even minor exposure to ambient humidity will cause the material to absorb moisture and fuse into solid, unusable blocks.

2. What is the fundamental difference between the flake format and pearls/pellets?

While chemically identical, the physical shape differs based on the manufacturing cooling process. The flat, broken format is highly cost-effective and dissolves rapidly due to its large surface area. Pearls (or pellets) are uniform, spherical beads that generate significantly less dust during handling and flow much easier through automated dosing machinery, though they typically command a slight price premium.

3. What is the safest procedure for diluting the dry chemical into a liquid solution?

Always adhere to the rule of adding the chemical to the water, never the reverse. Measure the appropriate volume of cold water into a corrosive-resistant mixing vessel. Slowly add the dry solid in small increments while stirring continuously. Because the reaction generates extreme heat, adding water to the solid can cause localized boiling and explosive splattering of the corrosive liquid. Always wear full PPE, including a face shield, during this process.