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D1005-95 解读
📐 Scope and Apparatus Requirements
ASTM D1005‑95 (Reapproved 2024) defines standard test methods for measuring dry‑film thickness of organic coatings including paints, varnishes, and lacquers using micrometers. The standard covers four procedures: A and B for stationary micrometers, and C and D for hand‑held micrometers. Procedures A and C are suitable for coatings on plane rigid surfaces with a recommended minimum thickness of 12.5 µm (0.5 mils). Procedures B and D are intended for free films, with minimum thickness dependent on the ability to remove the film without damage. The apparatus must include a dial comparator or micrometer with a presser foot diameter of 1.5 mm to 3.0 mm (¹⁄₁₆ in. to ⅛ in.), resolution of 2.5 µm (0.1 mil), and an applied load between 140 kPa and 275 kPa (20 psi to 40 psi).
This test method is particularly useful for free films and laboratory test panels, but accuracy can be affected by coating deformability and substrate uniformity. The values stated in SI units are the standard; imperial values in parentheses are for information only.
⚙️ Testing Procedures and Calibration
Procedure A uses a stationary micrometer for coatings on rigid surfaces, while Procedure B requires a smooth uncoated test plate for free film measurement. Procedures C and D utilize hand‑held micrometers for similar applications. Calibration must be verified by zeroing the instrument with closed anvils and measuring shims of known thicknesses to construct a calibration curve. Regular calibration ensures reliable measurements. Referenced standards include ASTM D823 for producing uniform test films and ASTM D2370 for tensile properties of organic coatings.
📊 Key Specifications and Tolerances
| 🟦 Procedure | 📏 Micrometer Type | 📐 Application | 🎯 Minimum Thickness |
|---|---|---|---|
| A | Stationary | Plane rigid surfaces | 12.5 µm (0.5 mils) |
| B | Stationary | Free films | Function of film removal |
| C | Hand‑held | Plane rigid surfaces | 12.5 µm (0.5 mils) |
| D | Hand‑held | Free films | Function of film removal |
| ⚡ Presser Foot Specification | Details |
|---|---|
| Diameter | 1.5 mm – 3.0 mm (¹⁄₁₆ in. – ⅛ in.) |
| Resolution | 2.5 µm (0.1 mil) |
| Load | 140 kPa – 275 kPa (20 psi – 40 psi) |
Regular calibration with known thickness shims is essential for maintaining measurement accuracy.
Avoid using this method for coatings that are easily deformable under the specified load.
❓ Frequently Asked Questions
🔍 What is the minimum thickness for Procedures A and C?
Procedures A and C are not recommended for films thinner than 12.5 µm (0.5 mils).
💡 How do I calibrate the micrometer?
Set the micrometer to zero with the anvils closed, then measure shims of known thicknesses to build a calibration curve.
⚡ What affects the accuracy of this test method?
Coating deformability and substrate uniformity are key factors influencing accuracy.
📌 Which procedure should I use for free films?
Use Procedure B with a stationary micrometer or Procedure D with a hand‑held micrometer for free films.