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D6404-99 – Standard Test Method Technical Guide
📜 Scope and Terminology of D6404-99
ASTM D6404-99 (Reapproved 2020), officially titled Standard Practice for Sampling Vegetable Materials Containing Tannin, provides a standardized methodology for obtaining representative samples from shipment lots of botanical materials containing tannin. This standard is essential for the tanning industry, covering vegetable tanning materials and tannin extracts to ensure analytical samples accurately reflect the average quality and variation within an entire lot.
The standard outlines key definitions critical for its application. All values are reported in SI units, with non-SI equivalents provided for reference only. It is the responsibility of the user to establish appropriate safety, health, and environmental practices.
| 📏 Term | 📖 Standard Definition |
|---|---|
| Tannin | An astringent substance found in the various parts of plants such as bark, wood, leaves, nuts, fruits, roots, etc. |
| Vegetable Tannins | Mixtures of substances (natural products) obtained from plant tissues by water extraction which have the chemical and physical properties necessary to convert animal hides and skins into leather. |
| Quartering | A method described in this practice of reducing the size of samples without impairing their representative quality. |
🔬 Apparatus and Sampling Methodology
To ensure representativeness, specific apparatus is required by the standard. Sampling must be performed using the prescribed equipment, employing the quartering technique for sample size reduction. The standard references Terminology D1517 and ALCA Method J10 for supplementary guidance.
| 🔧 Apparatus | ⚙️ Specification | 🎯 Purpose in Sampling |
|---|---|---|
| Analytical Balance | Accuracy of ±10 g (±0.35 oz) | To weigh the specified quantity of material for analysis accurately. |
| Canvas Cloth | 11-oz weight; sufficient size | Provides a clean, durable surface for thoroughly mixing and dividing the sample during the quartering process. |
The quartering method involves thoroughly blending the entire sample on the canvas and dividing it into four equal parts. Opposite quarters are combined to reduce the sample size while preserving the overall composition of the original lot. This process can be repeated until an economical and convenient quantity for analysis is achieved.
⚠️ Critical Procedural Note: The standard explicitly states that no directions for sampling can replace the judgment, skill, and previous experience of the personnel involved. These procedures are intended to supplement that expertise and serve as a common method for all contracting parties.
⏳ Significance and Critical Factors
This practice allows parties to agree on the extent of quality variation in different portions of a lot, as well as the average quality of the entire shipment. Because tanning materials contain varying amounts of moisture depending on their nature and climatic conditions, the standard mandates that sampling be conducted as quickly as possible consistent with thoroughness to avoid compromising analytical accuracy.
🚨 Moisture Sensitivity: Tanning materials contain moisture in varying amounts. Sampling must be carried out as quickly as is consistent with thoroughness in order to avoid changes in moisture content.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D6404-99?
The standard covers obtaining representative samples from shipment lots of botanical materials containing tannin specifically for use in the leather tanning industry.
💡 What is the “quartering” method described in the standard?
It is a sample reduction technique used to decrease the size of a sample without impairing its representative quality by mixing, dividing into four equal parts, and combining opposite quarters.
⚡ Why is moisture content a critical factor during sampling?
Changes in moisture content can skew the analytical results. The standard requires the sampling process to be done quickly to preserve the integrity of the sample.
📌 What specific apparatus does the standard require?
The standard specifies an analytical balance with an accuracy of ±10 g (±0.35 oz) and an 11-oz weight canvas of sufficient size for mixing and quartering.