Red granular ammonium chloride is ordinary granular ammonium chloride carrying an added colourant. The colour is a marker and nothing else: it changes no chemical, agronomic or physical property of the salt beyond appearance. It is worth understanding precisely what the marker is for, because a colour that carries an implied claim it cannot support is worse than no colour at all.
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 | Red to reddish-pink granules; the underlying salt is white, and the colour is entirely due to added colourant |
Specification
| Parameter | Value | Basis |
|---|---|---|
| NH₄Cl content | ≥ 94–96 % | Typical commercial range for agricultural material |
| Nitrogen (N) | ≥ 25.0–25.4 % | Typical commercial range |
| Moisture | ≤ 0.5–1.0 % | Typical commercial range |
| Particle size | 2–4 mm typical | Typical commercial cut |
| Colourant | Identity and inclusion level must be declared in the specification. No figure is given here — colourant loading varies by producer and by the intensity required, and quoting a nominal percentage would be invention | To be declared |
| Colour uniformity | Assess visually against a retained reference sample | Method to be agreed |
Properties
Solubility, hygroscopicity, thermal behaviour, dissolution enthalpy and solution pH are those of ammonium chloride and are not measurably altered at typical colourant loadings — approximately 37 g per 100 g water at 20 °C, endothermic dissolution near +14.8 kJ/mol, solution pH 4.5–6.0 at 5 %, dissociation on heating with apparent sublimation near 337.6 °C.
The colourant introduces its own behaviour, which the buyer should establish before committing. Whether it dissolves with the salt or remains as a suspended residue determines whether the product can be used in any solution application. Whether it transfers to wet hands, damp equipment, packaging or wet soil determines the practical nuisance level. Whether it is light-stable determines how the product looks after storage in a lit warehouse. None of these are chemical unknowns, but they are colourant-specific and cannot be inferred from the salt.
Applications
The commonly stated reasons for colour-marking ammonium chloride are, first, that the undyed material is a white crystalline salt visually similar to edible salt and to several other white fertilizer and industrial salts, so a colour marker reduces the risk of misidentification in a store and of diversion into food use; and second, that in a mixed-inventory warehouse a colour distinguishes agricultural or technical material from feed or food material at a glance, before any label is read. A third, practical benefit in the field is that coloured granules are visible on soil, which lets an operator see coverage and overlap during spreading.
Handling and storage
Storage requirements are those of granular ammonium chloride: dry, sealed, off the floor, away from alkaline materials and from copper alloys and unprotected steel in humid conditions. Add one precaution: assume the colourant will stain. Keep coloured material away from equipment, packaging or floors where a residual tint would be unacceptable, and do not use shared handling equipment between coloured and uncoloured product where colour carry-over into the uncoloured stream would defeat the purpose of the marker.
Notes
Colour is a convention, not a standard. It has no fixed international meaning, and the same red is used by different producers for different purposes. Do not treat a colour as evidence of grade, purity or origin, and do not build an incoming-goods procedure that relies on it. Verify grade by certificate of analysis and by test. The colour tells you which drum in your own warehouse you are looking at, and that is a genuine benefit, but it is the whole of the benefit.