Dyed compacted granular ammonium chloride combines two independent modifications of the base salt: compaction, which changes particle mechanics, and colouring, which changes only appearance. The two interact in one specific and practically important way — the compaction route determines whether the colour is distributed throughout the granule or only on its surface, and that determines how the colour behaves under abrasion.
Substance identity
| Chemical name | Ammonium chloride |
| Synonyms | Sal ammoniac, muriate of ammonia |
| Formula | NH₄Cl |
| CAS | 12125-02-9 |
| Molar mass | 53.49 g/mol |
| Appearance | Coloured angular granules with fractured faces; the base salt is white and all colour is from added colourant |
Specification
| Parameter | Value | Basis |
|---|---|---|
| NH₄Cl content | ≥ 94–96 % | Typical commercial range |
| Nitrogen (N) | ≥ 25.0–25.4 % | Typical commercial range |
| Moisture | ≤ 0.5–1.0 % | Typical commercial range |
| Particle size | 2–4 mm typical cut | Typical commercial range |
| Colourant identity and loading | To be declared by the producer | No representative figure quoted — it varies too widely to state honestly |
| Colour uniformity | Assess against a retained reference sample; specify whether freshly fractured surfaces must also be coloured | Method to be agreed |
Properties
Solubility, hygroscopicity, dissolution enthalpy, thermal behaviour and solution pH are those of ammonium chloride and are not measurably changed at typical colourant loadings: approximately 37 g per 100 g water at 20 °C, endothermic dissolution at about +14.8 kJ/mol, 5 % solution pH 4.5–6.0, dissociation to NH₃ and HCl on heating.
The point specific to this product is where the colourant sits. If the colourant is blended into the powder feed before the rolls, it is distributed through the compacted sheet, and every fracture face produced by the subsequent crushing step is also coloured — the granule is coloured through. If instead the colourant is applied to already-formed granules, only the outer surface carries it, and any abrasion in handling exposes white salt beneath and generates white fines. Both routes are used and neither is inherently wrong, but they produce visibly different products after a long logistics chain, and the difference is not visible in a fresh sample. Ask which route the producer uses.
Applications
The colour serves identification. Undyed ammonium chloride is a white crystalline salt with close visual analogues in both the food and fertilizer categories, and a colour marker distinguishes non-food material at a glance in a mixed store, reduces the risk of misidentification during handling, and makes coverage visible on soil during spreading. The compaction serves handling — dust reduction, storage stability, spreader performance and blend compatibility. The two are chosen for entirely separate reasons and should be specified separately.
Handling and storage
As for compacted granular material: dry, sealed storage, limited drop heights to control attrition, no contact with alkaline materials, and protection of copper alloys and steel in humid conditions. Additionally, assume colour transfer to wet surfaces, equipment and hands, and do not share handling equipment with product that must remain uncoloured. Where colour is a control measure in a warehouse, verify that abrasion in transit has not degraded it to the point where it no longer distinguishes the material reliably.
Notes
Colour is not evidence of grade, purity or origin, and it has no standardised meaning between producers or markets. Verify the product by certificate of analysis. Also confirm the colourant’s fate in water before using dyed material in any dissolved application — a colourant that remains as suspended residue will show up in the solution and may be unacceptable downstream.