Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D5653-95 – Standard Test Method Technical Guide
ASTM D5653-95 (Reapproved 2000) establishes the definitive requirements for Copper Dimethyldithiocarbamate (CDDC), a fixed water-insoluble wood preservative chelate formed in situ. Unlike conventional single-solution treatments, CDDC utilizes a precise dual-treatment process where a bivalent copper ethanolamine (2-aminoethanol) solution is followed by a sodium dimethyldithiocarbamate solution to form the active preservative directly within the wood’s cellular matrix.
🧬 Composition and Dual Treatment Process
The first treating solution consists of bivalent copper (Cu²⁺) derived from a copper ethanolamine complex dissolved in water. This complex must be completely water-soluble at 5°C to ensure stability under low-temperature application conditions. The second treatment introduces an aqueous solution of sodium dimethyldithiocarbamate. The reaction between these two components within the wood yields the final protective copper dimethyldithiocarbamate chelate, which is characterized by its high affinity for the wood cell wall.
🚫 Excluded Copper Sources: The standard explicitly prohibits the use of cupric salts of mineral acids for the bivalent copper source. Approved materials must be in excess of 95% purity and include cupric hydroxide, cupric oxide, and basic cupric carbonate.
⚙️ Specification Requirements for Treating Solutions
Stringent chemical controls are mandated for each treatment stage to ensure the correct stoichiometry and efficacy of the final preservative. The weight ratio of ethanolamine to bivalent copper in the treating solution must be maintained at a minimum of 1.70. Furthermore, both active components must be sourced from materials exceeding 95% purity on an anhydrous basis to prevent undesirable side reactions.
| 📏 Parameter | 🟦 Solution Stage | 🎯 Specified Requirement |
|---|---|---|
| Ethanolamine : Cu²⁺ Weight Ratio | First Treatment | Minimum 1.70 |
| Bivalent Copper Source Purity | First Treatment | > 95% by weight (anhydrous) |
| NaDMDC Purity | Second Treatment | > 95% by weight (anhydrous) |
| Solubility of Cu Complex | First Treatment | Complete at 5°C |
💡 Labeling Compliance: Commercial preservative components for both treatment stages must be clearly labeled with their total content of active ingredients to facilitate accurate field mixing and application ratios.
📊 Analytical Test Methods and Verification
Verification of the preservative component elements and the final chelate fixation is conducted using standardized analytical methods. ASTM D5653 directly references AWPA standards for these critical quality control steps, specifically adopting SI units as the standard for all stated values.
| 📐 Analyte | ⚡ Analytical Method | 📋 Reference Standard |
|---|---|---|
| Preservative Elemental Composition | X-Ray Spectroscopy | AWPA A 9 |
| CDDC Chelate Content | Colorimetry | AWPA A 25 |
These tests ensure the treated wood retains the correct average weight ratios of components, providing reliable performance as a fixed wood preservative system.
❓ Frequently Asked Questions
🔍 What does the acronym CDDC stand for, and how is it formed?
CDDC stands for Copper Dimethyldithiocarbamate. It is formed inside the wood through a sequential dual treatment of a copper ethanolamine complex followed by sodium dimethyldithiocarbamate, as specified in ASTM D5653.
💡 What is the critical ethanolamine-to-copper ratio requirement?
The treating solution must maintain a minimum ethanolamine-to-bivalent copper weight ratio of 1.70. This ensures the copper complex is fully chelated and meets the required solubility standard at 5°C.
⚡ What raw material purity levels does the standard require?
Both the bivalent copper source and the sodium dimethyldithiocarbamate must exhibit a purity exceeding 95% on an anhydrous basis to ensure consistent preservative formation.
📌 Which specific test methods are referenced for chemical analysis?
The standard mandates the use of AWPA A 9 (X-Ray Spectroscopy) for elemental preservative analysis and AWPA A 25 (Colorimetry) for the analysis of the CDDC chelate in the treated wood.