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D2247-15 – Standard Test Method Technical Guide
🎯 Overview and Scope of Practice D2247
Practice D2247 covers the basic principles and operating procedures for testing the water resistance of coatings by exposing coated specimens in an atmosphere maintained at 100 % relative humidity. The defining mechanism of this practice is the creation of a slight temperature differential within the exposure area, causing warm, saturated air to deposit condensation uniformly onto the surfaces of cooler test specimens. The values stated in SI units are regarded as the standard, with imperial equivalents provided for reference only.
Key Distinction: The condensation in this practice forms on all surfaces of the test specimen due to a temperature differential. This differs from practices that deposit water droplets via spray (e.g., D1735) or immersion (e.g., D870).
⚙️ Test Procedure and Key Conditions
The core test environment is a chamber maintained at 100 % relative humidity. Condensation is induced by ensuring the test specimens are cooler than the surrounding saturated air. The standard specifies controlling these conditions to ensure consistent condensation formation but explicitly limits itself to the methodology of obtaining, measuring, and controlling this environment. Per Section 1.4, it does not specify methods for specimen preparation or criteria for evaluating results.
A critical feature distinguishing this practice from related methods is that the entire specimen is placed within the exposure area. This makes it suitable for not only flat coated panels but also for large or three-dimensional objects.
Important Note: Proper safety, health, and environmental practices must be established by the user. The standard does not address all safety concerns associated with its use. The quality of water used for the test atmosphere should meet Specification D1193 for Reagent Water.
📊 Evaluation Methods and Referenced Standards
While D2247 defines the exposure conditions, the assessment of test specimens relies on a suite of other ASTM standards. The tables below summarize key standards commonly applied in conjunction with this practice, as identified in Section 2.1.
| 🎯 Category | 📐 Standard | 🟦 Application in D2247 |
|---|---|---|
| Substrate Preparation | D609, D1730 | Standard practices for preparing steel and aluminum panels prior to coating. |
| Film Application | D823 | Standard practices for producing films of uniform thickness. |
| Blistering Evaluation | D714 | Evaluating the degree of blistering on coated surfaces. |
| Corrosion & Rusting | D610, D1654 | Evaluating the degree of rusting and effects of corrosive environments. |
| Adhesion Testing | D3359, D4541 | Rating adhesion by tape test or pull-off strength. |
| 📏 Standard | ⚡ Deposition Method | 🔍 Specimen Exposure |
|---|---|---|
| D2247 | Condensation (100% RH) | Entire specimen |
| D1735 | Water Fog / Spray | Typically front face |
| D4585 | Controlled Condensation | Front face |
| D870 | Water Immersion | Typically front face or full immersion |
❓ Frequently Asked Questions
🔍 What is the primary mechanism for water deposition in D2247?
The primary mechanism is condensation. A slight temperature differential is maintained within the test chamber. As warmer, saturated air passes over the cooler coated specimens, water condenses uniformly on all surfaces.
💡 How does D2247 differ from Practice D1735 (Water Fog)?
D2247 places the entire specimen inside the chamber, allowing condensation to form on all surfaces including the back. This is a significant difference from D1735, where condensation or water spray is typically limited to the front face of the specimen.
⚡ Does D2247 specify pass/fail criteria or specimen preparation?
No. As stated in Section 1.4, this practice is strictly limited to the methods of obtaining, measuring, and controlling the test conditions. Specimen preparation and evaluation of results must be conducted according to other applicable standards listed in Section 2.1.
📌 What types of test specimens are suitable for this practice?
Because the entire specimen is exposed to condensation, this practice is ideal for not only flat coated panels but also for large or three-dimensional objects. This makes it distinct from tests with front-face-only exposure requirements.