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D2337-01 – Standard Test Method Technical Guide
This standard test method, designated D2337‑01 (Reapproved 2014), provides a procedure for evaluating the freeze-thaw stability of multicolor lacquers. The values stated in SI units are regarded as the standard. This test method is critical for ensuring waterborne coatings maintain their integrity during cold storage and transit.
🧪 Test Method Overview and Significance
This test method covers the determination of the extent to which multicolor lacquers resist coagulation and coalescence when subjected to a standard freezing and subsequent thawing cycle. Waterborne coatings, when subjected to cycles of freezing and thawing, can undergo detrimental changes in application properties and overall performance characteristics. This specific procedure simulates the thermal stress of shipping and storage to evaluate the robustness of the coating formulation.
⚙️ Apparatus, Sample Preparation, and Test Procedure
Specimens of multicolor lacquers are placed in a chamber maintained at a specific low temperature for a controlled duration. The preparation and spacing of samples are critical to the validity of the test.
| 🟦 Test Parameter | 📏 Specification / Value |
|---|---|
| Freezing Chamber Temperature | ‑23 to ‑26 °C (‑10 to ‑15 °F) |
| Air Space Between Adjacent Specimens | At least 25 mm (1 in.) |
| Freezing Cycle Duration | 24 hours |
| Thawing Cycle Duration (Room Temp) | 24 hours |
| Spray Gun Tip Specification | 0.086 in. (2 mm) internal-mix, wide-spray nozzle |
| Viscosity Measurement | Stormer Viscometer per Test Method D562 |
Sample Requirements: For all gloss and semigloss multicolor lacquers, ten 1‑L (1‑qt) specimens are prepared. For flat multicolor lacquers, four 1‑qt specimens are required. The sample is boxed to ensure uniform consistency and appearance before filling. It is critical to record the initial consistency using a Stormer viscometer and fill the samples in baked varnish-lined containers, applying lids promptly to prevent evaporation loss.
⚠️ Critical Placement Requirement: Specimens under test must be placed on racks ensuring they do not touch the walls or bottom of the chamber. This ensures uniform air circulation and freezing conditions across all specimens. Maintain at least 25 mm of air space between adjacent cans.
📊 Control Standard Preparation and Evaluation
After the freeze-thaw cycle, the specimens are mixed, and the viscosity is adjusted back to the baseline reading. A control standard is prepared by spraying from a reserved specimen of the original product. The test sample is then sprayed under identical conditions and compared against the control standard to evaluate coagulation and coalescence.
| 🎨 Application Type | 📐 Spreading Rate (SI) | 📐 Spreading Rate (Imperial) |
|---|---|---|
| Complete Covering | 3.7 to 4.9 m²/L | 150 to 200 ft²/gal |
| Scatter Coat | 4.9 to 7.35 m²/L | 200 to 300 ft²/gal |
💡 Viscosity Adjustment Best Practice: The initial consistency is determined using a Stormer viscometer (Test Method D562) before freezing. After the 24-hour freeze and 24-hour thaw, the viscosity must be adjusted to this initial value. This step isolates the effect of the freeze-thaw cycle on the coating’s stability (coagulation/coalescence) rather than on viscosity drift.
❓ Frequently Asked Questions
🔍 What is the primary purpose of ASTM D2337‑01?
The standard specifically covers the determination of the extent to which multicolor lacquers resist coagulation and coalescence when subjected to a standard freezing and subsequent thawing cycle.
💡 What are the exact temperature and spacing requirements for the freezing chamber?
The chamber must be maintained at a temperature between ‑23 and ‑26 °C (‑10 and ‑15 °F). Specimens must have at least 25 mm (1 in.) of air space between the sides of adjacent cans and must not touch the walls or floor of the chamber.
⚡ How many test specimens are required for flat versus gloss lacquers?
For gloss and semigloss multicolor lacquers, nine specimens are placed under test (one is reserved as a control), requiring ten 1‑L (1‑qt) samples total. For flat multicolor lacquers, three specimens are placed under test, requiring four 1‑qt samples total.
📌 What are the specified spreading rates for the spray application in this test?
The fluid and atomizing pressures must be adjusted to achieve a spreading rate of 3.7 to 4.9 m²/L (150 to 200 ft²/gal) for complete covering, and 4.9 to 7.35 m²/L (200 to 300 ft²/gal) for a scatter coat application on white paper stock.