Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D475-67 – Standard Test Method Technical Guide
📐 Composition and Types of Pure Para Red Toner
This specification covers the red pigment commercially known as pure para red toner, available in two distinct Types: Type I (light) and Type II (dark). Both types must be in a soft dry form.
Type I consists solely of pure para red toner, light (1-(p-nitro-phenyl-azo)-2-naphthol) and is explicitly required to be free of any substrate. Type II also has a soft dry form but is mixed with a small quantity of 1-(p-nitro-phenyl-azo)-2-naphthol-7-sulfonic acid; it must also be free of any substrate. This key chemical distinction is what gives each type its specific hue and technical performance.
📌 Key Technical Note: The phrase “free of any substrate” is critical for qualification. Unlike extended pigments, Pure Para Red Toner contains no inert base material, ensuring maximum color strength and transparency per unit weight.
📊 Required Physical and Chemical Properties
The pigments must conform to strict limits regarding purity, chemical resistance, and physical form. The following table summarizes the mandatory requirements for both types.
| 🟦 Property | 📏 Type I Requirement | 📏 Type II Requirement |
|---|---|---|
| Ash, max, % | 3.0 | 3.0 |
| Moisture and other Volatile Matter, max, % | 1.0 | 1.0 |
| Coarse Particles (45-µm / No. 325 sieve), max, % | 1.5 | 1.5 |
| Solubility in Chloroform | Complete | … |
| Resistance to Acids | To pass test | To pass test |
| Resistance to Alkalis | To pass test | Equal to standard |
| Identity Test | To pass test | To pass test |
⚡ Critical Assessment: The mass color and character of the tint formed by mixture with a white pigment must be the same as, and the strength not less than, that of a reference sample mutually agreed upon by the purchaser and the seller. This comparative assessment is a central requirement of the specification.
🧪 Sampling and Test Methods
The standard defines a robust sampling plan for quality assurance. Two samples must be taken at random from different packages from each lot, batch, or day’s pack. For shipments without distinct unit markings, the ratio is two samples for each 10,000 lb (5,000 kg), with a minimum of two samples for shipments under 10,000 lb. At the option of the purchaser, samples may be tested separately or blended in equal quantities to form a composite sample.
All required tests—including those for coarse particles, resistance to acids and alkalis, and identity—shall be conducted strictly in accordance with ASTM Test Methods D 970.
❓ Frequently Asked Questions
🔍 What is the chemical difference between Type I and Type II?
Type I is composed entirely of pure 1-(p-nitro-phenyl-azo)-2-naphthol. Type II incorporates a small quantity of 1-(p-nitro-phenyl-azo)-2-naphthol-7-sulfonic acid, which modifies its shade to the “dark” variant.
💡 What are the maximum allowable limits for ash and moisture?
Both Type I and Type II must have an ash content no greater than 3.0% and a moisture and volatile matter content no greater than 1.0%. The maximum residue retained on a 45-µm (No. 325) sieve is 1.5%.
⚡ How is the tinting strength verified according to the standard?
The tinting strength and mass color must be compared to a reference sample mutually agreed upon by the purchaser and seller. The pigment is mixed with a white pigment and evaluated against a standard mixture prepared under identical conditions.
📌 What is the required sampling procedure for a shipment?
Two samples must be taken at random from different packages from each production unit. For larger shipments, two samples are taken for every 10,000 lb (5,000 kg), with a minimum of two samples for smaller shipments.