Caustic soda from India is exported as solid flakes, normally sold as caustic soda flakes 98%, and as liquid lye, a solution of sodium hydroxide in water. If you are comparing caustic flakes vs lye, flakes suit long routes and small stores, while lye suits plants that can receive liquid in bulk.
Either form is a corrosive dangerous good, so the first order must be planned around handling and shipping, not only the specification.
Flakes or lye: which do you need?
Flakes are about 98% sodium hydroxide by weight and are packed in bags, usually 25 kg. Lye is commonly sold at 48% to 50%, and sometimes at 32%, and moves in tank containers or bulk. If you pay freight on water, lye over a long route carries a lot of water. If you must dissolve flakes yourself, you need safe dissolving equipment, since the reaction releases heat. What caustic soda is and the forms it comes in explains the range.
What should the caustic soda assay show?
The caustic soda assay measures sodium hydroxide content, and a good certificate lists more than that.
- Sodium hydroxide content, with the titration method named.
- Sodium carbonate, which builds up when caustic absorbs carbon dioxide from the air.
- Chloride and sulphate, which matter for sensitive processes.
- Iron and other heavy metals, which matter for some uses such as textiles and chemicals.
- For lye produced by the membrane process, a low-chloride grade may be available if your application needs it.
Is caustic soda dangerous cargo?
Yes. Both solid and solution are corrosive and fall under dangerous goods rules for sea freight, with UN numbers and a hazard class that your shipper will apply. Is caustic soda dangerous cargo goes through the details, and IMDG classes explains the system. Use only UN-approved packaging, make sure labels and the DG declaration are correct, and confirm that your chosen shipping line accepts the cargo.
How do you find a reliable supplier?
Caustic soda is a chlor-alkali product, so the real producers operate chlor-alkali plants, and many export houses buy from them. Ask who produces the lot and ask for its certificate. Flakes are hygroscopic, so the packing and the container condition matter, and a bag that has taken on moisture can cake. Insist on loading supervision for a first order.
What should you check on arrival?
Check that the packaging is intact and carries the correct hazard labels, that the batch number matches the certificate, and that the bags have not taken in moisture. Take a sample under the safety procedure in your safety data sheet, wearing the protective equipment it lists, and titrate it against your specification. For lye, check the concentration, the colour and any sediment before you transfer the tank. Record the results the same day, because the claim period in your contract may be short. Never open or sample damaged packages without a safe procedure in place.
Next step
We find chlor-alkali producers that can supply your form and quantity, check samples and certificates, and supervise loading. We work only for the buyer, for one written fee agreed in advance. Book a free sourcing review with the form, quantity and destination port, or read how to find a genuine chemical manufacturer.