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D2449-88 – Standard Test Method Technical Guide
📐 Scope and Key Requirements
The ASTM D2449-88 specification defines the allowable limit for bale coating on natural rubber bales with rubber wrapper sheets. The average coating amount in the sample must not exceed 4 ± 0.1 g/kg of rubber, equivalent to 1 lb per 250 lb bale. Lots exceeding this limit are subject to rejection.
This specification is not applicable to natural rubber packaged with plastic wrappers, as no bale coating is used.
| 🟦 Parameter | 📏 Value |
|---|---|
| Maximum bale coating | 4 ± 0.1 g/kg |
| Equivalent for 250‑lb bale | 1 lb |
| Sampling standard | Practice D1485 |
⚙️ Test Procedures and Specimen Sizes
Two methods are provided: Method A (Ash Method) for all rubber grades and Method B (Brushing or Scraping Method) for smoked sheet rubbers only. Method B is not suitable for crepe rubbers due to coating penetration and removal difficulties.
| 📐 Method | 🎯 Specimen Size | ⚡ Tolerance |
|---|---|---|
| Method A (Ash) | 50 × 50 mm | ±1 mm |
| Method B (Brushing) | 150 × 150 mm | ±1 mm |
For Method A, the weight of each 50‑mm square specimen is recorded to the nearest 0.01 g. Ash content is determined per Test Methods D1278.
📊 Sampling and Significance
Sampling requires careful removal of portions from the outer wrapper sheets on three sides of the bale to minimize coating loss. The number of bales sampled follows Practice D1485 or agreement between parties.
The bale coating prevents adhesion during transportation and storage. However, excessive coating can impair compounded physical properties.
💡 Tip: To ensure accurate results, handle sampled portions with care and store them in a way that prevents loss of bale coating.
⚠️ Safety: This standard does not address all safety concerns. Users must establish appropriate safety, health, and environmental practices before use.
❓ Frequently Asked Questions
🔍 What is the maximum bale coating allowed?
The average bale coating must not exceed 4 ± 0.1 g/kg of rubber.
💡 Why is bale coating used?
Bale coating prevents rubber bales from sticking together during transportation and storage.
⚡ Which test method is used for crepe rubber?
Method A (Ash Method) is used for crepe rubber, as Method B is not suitable due to penetration through wrapper holes.
📌 How are samples taken from bales?
Sample portions are randomly removed from the outer wrapper sheets on any three sides of the bale, ensuring minimal coating loss.