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D209-81 – Standard Test Method Technical Guide
📐 Scope and Composition Requirements
This specification, ASTM D209‑81 (Reapproved 2023), covers the pigment commercially known as lampblack. The pigment is made by burning oils or tars to form a deposit of carbon (soot). It must be high grade and strictly free from oil, greasy matter, and any admixture of other substances. The standard defines stringent limits for both dry pigment and paste‑in‑oil forms.
| 🟦 Property (Dry Pigment) | 🎯 Requirement |
|---|---|
| Ash, max, % | 0.5 |
| Acetone extract, max, % | 1.0 |
| Moisture and other volatile matter, max, % | 3.0 |
| Coarse particles (residue on 45 µm / No. 325 sieve), max, % | 0.5 |
| Tone when diluted with zinc oxide | Clear‑blue‑gray |
⚠️ Sampling Protocol: Two samples shall be taken from different packages per lot or production unit. For shipments under 10,000 lb (4540 kg), two samples are required. For larger shipments, two samples must be taken per 10,000 lb. At the buyer’s option, samples from the same unit may be blended into a composite before testing (Section 4.1).
⚙️ Properties for Lampblack Paste in Oil
When supplied as a paste in oil, the pigment must be thoroughly ground with linseed oil. The paste shall not be caked in the container and must break up readily in oil to form a smooth paint of brushing consistency. It must mix readily without curdling with linseed oil, turpentine, or volatile petroleum spirits.
| 🟦 Property (Paste in Oil) | ⚡ Requirement |
|---|---|
| Pigment, min, % | 25 |
| Linseed oil, max, % | 75 |
| Moisture and other volatile matter, max, % | 0.7 |
| Coarse particles & skins (of the dry pigment), max, % | 1.0 |
💡 Tinting Strength & Color: The mass color, character of the tint, and tinting strength must fall within mutually agreed‑upon limits of a standard acceptable to both the purchaser and the seller (Section 3.3). These properties are evaluated using Test Method D387.
📊 Verification and Test Methods
Compliance with D209‑81 is determined through specific referenced ASTM test methods. Coarse particles are evaluated using Test Methods D185. The composition of paste in oil (pigment, linseed oil, moisture, and volatile matter) is determined by Test Methods D1208. Mass color and tinting strength are assessed with Test Method D387. Any test procedures not explicitly covered in the standard must be mutually agreed upon between the purchaser and the seller.
The pigment must be of high grade in every respect. The mass color and character of the tint formed by a mixture with a white pigment shall be within mutually agreed‑upon limits.
❓ Frequently Asked Questions
🔍 What are the maximum impurity limits for dry lampblack pigment?
The standard specifies a maximum ash content of 0.5%, a maximum acetone extract of 1.0%, and a maximum moisture and volatile matter of 3.0%. The total residue retained on a 45 µm (No. 325) sieve must not exceed 0.5%.
💡 How is lampblack defined in the standard, and what is its required tone?
Lampblack is defined as a pigment made by burning oils or tars to form a deposit of carbon or soot. It must be free from oil, greasy matter, and any admixture. When the dry pigment is diluted with zinc oxide, the resulting tone must be a “clear‑blue‑gray.”
⚡ What are the specific requirements for the Paste in Oil form?
The paste must contain a minimum of 25% pigment and a maximum of 75% linseed oil. Moisture and volatile matter are capped at 0.7%, and coarse particles and skins must not exceed 1.0% of the dry pigment. The paste must also be smooth, uncaked, and mix readily without curdling.
📌 Which ASTM test methods are specifically referenced in D209‑81?
The standard directly references D185 for coarse particles, D1208 for common properties of pigments (pigment, oil, and volatile content in paste), and D387 for mass color and tinting strength.