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D1413-07 – Standard Test Method Technical Guide
📐 Scope, Significance, and Referenced Standards
This test method, D1413-07´1, establishes a laboratory soil-block culture procedure to determine the minimum amount of a wood preservative required to prevent decay under optimized decay conditions, known as the threshold retention. It is essential in the development of new wood preservatives and preservative systems. The standard coordinates the preparation of test cultures, impregnation of wood blocks, and exposure to specific wood-destroying fungi as outlined in the Scope (Section 1). The Significance and Use (Section 4) confirms that results are used to facilitate target retentions for subsequent field and termite tests.
| 🟦 Key Parameter | 📏 Governing Standard / Specification |
|---|---|
| Test Objective | Determine Threshold Retention (Section 1.1) |
| Failure Definition | Loss in weight of treated wood block (Section 3.1) |
| Organic Solvent | D841 – Nitration Grade Toluene |
| Reagent Water | D1193 – Specification for Reagent Water |
| Test Sieves | E11 – Woven Wire Test Sieve Cloth |
| Field Stake Correlation | D1758 – Test Method with Stakes |
| Termite Correlation | D3345 – Lab Evaluation for Termites |
| Sister Standard | AWPA E10 – Soil-Block Cultures |
📌 Key Insight: The results derived from this laboratory method are explicitly used to facilitate target retentions for subsequent field stake tests (D1758) and termite resistance tests (D3345). The threshold retention identified here serves as a baseline for efficacy in more complex environments, bridging lab performance to field application.
⚙️ Test Procedure and Threshold Determination
The Summary of Test Method (Section 3) specifies that conditioned blocks of wood are impregnated with different concentration solutions of a preservative to produce a series of retentions. After periods of conditioning (Section 12) and optional weathering to evaluate preservative permanence (Section 13), the blocks are exposed to pure cultures of wood-destroying fungi. The minimum amount of preservative that protects the blocks is defined as the threshold retention for that organism. The procedural sequence demands strict coordination between culture preparation and block placement.
| 📐 Procedural Step | ⚡ Standard Section |
|---|---|
| Summary of Test Method | Section 3 |
| Wood and Test Blocks | Section 7 |
| Preparation of Test Cultures | Section 10 |
| Preparation and Impregnation of Blocks | Section 11 |
| Conditioning Treated Blocks | Section 12 |
| Preservative Permanence (Weathering) | Section 13 |
| Stabilization and Placement in Bottles | Section 14 |
| Incubation and Duration of Test | Section 15 |
| Calculation of Weight Losses | Section 17 |
| Evaluation and Refining the Threshold | Sections 18 & 19 |
⚠️ Important Note on Test Limitations: As stated in Section 1.1, this test is performed under “optimum laboratory conditions.” Failure to protect is defined strictly by a loss in weight of the treated wood blocks, indicating biological degradation. The threshold retentions generated are minimums for controlled lab conditions and are intended as targets for further higher-tier field testing.
❓ Frequently Asked Questions
🔍 What exactly does “Threshold Retention” mean in D1413?
It is the minimum amount of preservative that protects the impregnated blocks against decay by a given test fungus. Failure is evidenced by a measurable loss of weight from the wood blocks, indicating fungal decay.
💡 How is the preservative applied to the wood test blocks?
Blocks are impregnated with different concentration solutions of a preservative in water or a suitable organic solvent. The specific requirement for organic solvent-based systems references D841 (Nitration Grade Toluene).
⚡ How do D1413 results correlate with real-world durability?
The standard explicitly states (Section 4.1) that results are used to facilitate target retentions in subsequent field stake tests (D1758) and termite resistance tests (D3345). It establishes an intrinsic toxicity baseline under optimal decay conditions but is not a direct field rating.
📌 Which standards are directly linked to D1413 for a full preservative evaluation?
The standard directly references D1758 for field testing with stakes, D3345 for laboratory termite evaluations, and aligns with AWPA E10. Referenced material standards include D841 (Toluene), D1193 (Reagent Water), and E11 (Test Sieves).