NaOH — The Number You Are Buying
Purity expressed as NaOH is the active alkali. At 99.0% minimum, a tonne of product delivers at least 990 kg of sodium hydroxide. This is the figure your charge calculation uses. If a supplier quotes 98% or an unstated "technical grade", your dose rate has to rise to compensate and the cheaper price per tonne stops being cheaper.
Na2CO3 — Carbonate
Sodium hydroxide reacts with carbon dioxide in air to form sodium carbonate. Carbonate is a much weaker alkali, so it is essentially dead weight in a saponification or a pulping charge. It is also a direct indicator of how well the product has been protected from the atmosphere during production, packing and storage. We declare carbonate at 0.5% maximum on every grade.
NaCl — Chlorides
Chloride is a residue of the chlor alkali process. It matters where the dosing loop or the process vessel is stainless steel, because chloride drives pitting and stress corrosion cracking. Our flake grade holds chlorides at 0.03% maximum and our pearl and solid grades at 0.05% maximum.
Fe2O3 — Iron
Iron is the impurity that shows up visually. In textile dyeing and in bleached paper grades, iron can appear as staining or as shade variation that is only obvious after the dye stage, by which point the batch is already made. Our flake grade is held to 0.005% maximum iron, ten times tighter than the pearl and solid grades, precisely because it is the grade those industries buy.
The Standard Behind The Numbers
Our industrial grade caustic soda is produced strictly in accordance with the Chinese national standard GB 209-2006. When a buyer asks what standard our product is made to, that is the answer. Export products are checked by quality inspection agencies such as SGS CIQ and INTERTEK.
What Is Not On The Sheet
A specification sheet says nothing about packaging condition, lead time or documentation, and those are the three things that most often go wrong on an import. Ask separately about bag construction, about the marking on the bag face and about which documents will travel with the cargo.
Transport Classification
Solid sodium hydroxide is UN 1823, class 8, corrosive. This is not a quality parameter but it belongs in your specification conversation because it determines the marking on the bag and the paperwork for the shipment.
| Product | NaOH | Na2CO3 | NaCl | Fe2O3 |
|---|---|---|---|---|
| Caustic Soda Pearls 99% | 99.0% Min | 0.5% Max | 0.05% Max | 0.05% Max |
| Caustic Soda Flakes 99% | 99.0% Min | 0.5% Max | 0.03% Max | 0.005% Max |
| Caustic Soda Solid 99% | 99.0% Min | 0.5% Max | 0.05% Max | 0.05% Max |
