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D6403-99 – Standard Test Method Technical Guide
ASTM D6403-99 (Reapproved 2020) provides a standardized test method for determining the moisture content in raw and spent materials destined for tannin analysis. The moisture content is operationally defined as the weight loss due to evaporation in a drying oven, with values reported in SI units.
📐 Scope and Terminology
This test method is specifically intended for materials extracted for tannin analysis. The moisture content is defined strictly by the weight loss experienced during drying. Key terms used throughout the standard are summarized below.
| 🟦 Term | 📖 Definition |
|---|---|
| Raw Material | Any of the various parts of plants used as a source of vegetable tannins. |
| Spent Material | Plant tissue by-products from industrial processes which may contain significant quantities of vegetable tannins. |
| Tannin | An astringent substance found in plant parts such as bark, wood, leaves, nuts, fruits, and roots. |
| Vegetable Tannins | Mixtures of natural substances obtained from plant tissues by water extraction, possessing the chemical properties to convert hides into leather. |
⚙️ Procedure and Significance
A specimen prepared according to Practice D6405 is dried overnight in a forced-air oven; the resulting weight loss represents the moisture content. This value is essential for calculating other analytical results on a moisture-free basis. Sampling must be performed quickly and thoroughly to prevent moisture changes due to the environment. The method references ASTM D6405 and ALCA Method A6.
| 📏 Designation | 📐 Title | 🎯 Unit System |
|---|---|---|
| D6403-99 (Reapproved 2020) | Standard Test Method for Determining Moisture in Raw and Spent Materials | SI Units |
💡 Key Practice: To avoid changes in moisture content, collect specimens as quickly as consistent with thoroughness, accounting for climatic conditions.
🔬 Error Sources and Data Use
Negative errors may occur from retention of moisture by components such as hydrated salts or water bound to organic structures, or from oxidation of tannins. Positive errors may arise from volatilization of non-water components. This test method is under the jurisdiction of ASTM Committee D31 on Leather.
⚠️ Potential Errors: Be aware that retention of moisture or oxidation can cause negative errors, while volatilization of components other than water can cause positive errors in the determination.
❓ Frequently Asked Questions
🔍 What is the moisture content based on?
Moisture content is operationally defined as the weight loss due to evaporation in a drying oven.
💡 Why is moisture determination important?
The moisture value is used to calculate the results of other analyses on a moisture-free basis, ensuring accuracy and comparability.
⚡ What errors can affect the measurement?
Negative errors can occur from moisture retention or oxidation, while positive errors can result from volatilization of non-water substances.
📌 How should samples be handled?
Sampling must be performed quickly and thoroughly to avoid changes in moisture content from environmental conditions.