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D1338-99 – Standard Test Method Technical Guide
ASTM D1338-99 (Reapproved 2021) provides a standardized methodology for determining the working life of liquid or paste adhesives that possess a relatively short usable pot life. This practice, under the jurisdiction of Committee D14 on Adhesives, is essential for quality assurance and process control in industries using reactive or fast-drying adhesives. It outlines two distinct procedures—Consistency Testing and Bond Strength Testing—allowing manufacturers and users to specify performance criteria based on the application’s primary functional requirements. The values stated in SI units are regarded as the standard.
📋 Scope and Definitions
This practice is intended to determine whether the working life of an adhesive conforms to its minimum specified limit. It applies to three primary categories of adhesives:
- Self-contained liquid or paste adhesives
- Adhesives requiring the addition of a catalyst, hardener, filler, or thinner just prior to use
- Powdered or flaked adhesives which are dissolved in water or other solvent and are used as liquid or paste adhesives
According to the standard, the working life of an adhesive is defined as “the time elapsing between the moment an adhesive is ready for use and the time when the adhesive is no longer usable.” Key terminology follows the definitions found in Terminology D907.
⚙️ Consistency Procedure: Apparatus and Environment
The consistency procedure measures the change in viscosity or workability over time. The adhesive is prepared, and its consistency is measured at intervals under strictly controlled conditions until it falls outside the specified limits. The standard specifies precise apparatus and conditions for this testing to ensure reproducibility.
| 🔧 Component | 📏 Specification | 🎯 Requirement |
|---|---|---|
| Viscometer | Type | Any suitable means; results must be expressed in fundamental units |
| Controlled-Atmosphere Chamber | Temperature | 23 ± 1.1°C (73.4 ± 2°F) |
| Controlled-Atmosphere Chamber | Relative Humidity | 50 ± 2% |
| Sample Container | Beaker (heat-resistant glass) | 400 mL capacity; 76 mm (3 in.) diameter x 102 mm (4 in.) high |
| Stirring Rod | Material | Glass, stainless steel, or other unreactive material |
⚠️ Maintain Strict Environmental Controls: Per the standard, the atmosphere must be strictly maintained at 23 ± 1.1°C and 50 ± 2% RH unless otherwise agreed upon by the purchaser and the manufacturer. Alternative controlled conditions are permissible only by mutual agreement, as any deviation can significantly impact the measured working life.
🔗 Bond Strength Evaluation Method
For applications where final bond strength is the critical quality metric, this procedure assesses working life by fabricating and testing specimens at intervals during the adhesive’s usable life. The adhesive is considered to have exceeded its working life when the average test values fall below the specified minimum. The standard references several key ASTM test methods for this purpose.
| 📄 Referenced Standard | ⚡ Test Description |
|---|---|
| ASTM D897 | Tensile Properties of Adhesive Bonds |
| ASTM D906 | Strength Properties of Adhesives in Plywood Type Construction in Shear by Tension Loading |
| ASTM D1002 | Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal) |
| ASTM D1084 | Test Methods for Viscosity of Adhesives (supports the Consistency Procedure) |
💡 Broad Application Scope: This practice is designed to cover adhesives that harden chemically, evaporate solvent, or simply change consistency (Section 4.1). It is universally applicable to two-part epoxies, filled pastes, solvent-based contact adhesives, and powders dissolved prior to use, making it highly versatile for production quality control testing.
❓ Frequently Asked Questions
🔍 What is the official definition of “working life” per ASTM D1338-99?
The standard defines working life as “the time elapsing between the moment an adhesive is ready for use and the time when the adhesive is no longer usable.” This is determined based on the acceptance criteria established in the consistency or bond strength procedures.
💡 What are the required environmental conditions for the Consistency Test?
The controlled atmosphere must be strictly maintained at a temperature of 23 ± 1.1°C (73.4 ± 2°F) and a relative humidity of 50 ± 2%. Alternative conditions are permissible only if specifically agreed upon by the purchaser and the manufacturer.
📌 Which bond strength test methods are referenced in this practice?
The practice references ASTM D897 (Tensile Properties), D906 (Plywood Shear by Tension Loading), and D1002 (Single-Lap-Joint Shear for Metal-to-Metal) as the standard methods for evaluating the bond strength aspect of an adhesive’s working life.
© 2026 TNLab — This article is a technical interpretation for reference only. The original standard as published by ASTM International takes precedence.