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D2175-97 – Standard Test Method Technical Guide
📐 Apparatus and Specimen Specifications
The test apparatus requires two metal plane parallel circular concentric faces. The movable platen has an area of 20 cm², and both platens must be parallel to within 0.1 mm. Specimens are prepared from sheets at least 64 mm square, with samples taken at least 300 mm apart for roll paper.
| 🟦 Parameter | 📏 Requirement | 🎯 Tolerance |
|---|---|---|
| Movable platen area | 20 cm² | Specified |
| Applied pressure | 250 kPa | ±10 kPa |
| Platen separation | >25 mm | N/A |
| Reading accuracy | 0.5 mm | ±0.25 mm |
Tip: Condition paper per Practice D685 before testing for consistent bulking results.
⚙️ Test Procedure and Pressure Application
Place a stack of sheets between the platens. Lower the movable platen at 250 kPa and read the distance to 0.5 mm. In procedure 10.1, use a desired number of sheets; in 10.2, use the number that bulks 25 mm. The pressure must be maintained within 250 ± 10 kPa.
Warning: Inconsistent pressure application can lead to errors. Ensure the instrument is calibrated regularly.
📊 Key Measured Properties
Book bulk is the thickness of a specified stack of sheets under pressure. The bulking number indicates the bulk per sheet, useful for comparing paper grades. Both measurements help book manufacturers estimate final product thickness.
| 🟦 Property | 📐 Description | ⚡ Importance |
|---|---|---|
| Book Bulk | Stack thickness at 250 kPa | Predicts book thickness |
| Bulking Number | Bulk per sheet or page | Compares paper quality |
❓ Frequently Asked Questions
🔍 What is the scope of D2175-97?
This standard covers the determination of book bulk and bulking number for printing paper under a specific pressure.
💡 How are test specimens chosen?
Per Practice D585, with separate cut sheets or samples from rolls at least 300 mm apart. Sheets must be at least 64 mm square.
⚡ What is the required pressure?
The test pressure is 250 kPa with a tolerance of ±10 kPa, applied to the stack of sheets.
📌 Why is book bulk important?
It helps book manufacturers and printers determine the thickness of a book from a given paper, ensuring proper binding and appearance.