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D5039-97 – Standard Test Method Technical Guide
ASTM D5039-97 (Reapproved 2002), concurrently recognized as TAPPI T 455, establishes standard test methods for identifying the wire side of paper manufactured on a one-wire fourdrinier paper machine. Distinguishing between the wire side and the felt side is often required as these sides generally exhibit differences in physical and chemical characteristics.
🧪 Test Methods Summary and Applicable Scope
These test methods provide a systematic approach using six distinct procedures. Because coated, surface-treated, and certain high-grade papers may resist easy identification, the standard recommends progressing through the procedures if an earlier one fails. Identification is considered established if any single procedure yields a clear result.
⚠️ Applicability Warning: These procedures are strictly designed for paper from a one-wire fourdrinier machine. They are explicitly stated as not applicable to paper made on cylinder, twin-wire, or other special machines.
🔬 Detailed Procedures and Key Parameters
The six procedures are summarized in the table below. The most definitive visual methods are Direct Observation (Procedure A) and the Carbon Smudge test (Procedure B), which rely on identifying the distinct wire pattern left on the paper surface during formation.
| 🟦 Procedure | 📐 Method Title | 📏 Critical Technical Specifications |
|---|---|---|
| A | Direct Observation | Light angle < 10°. Wire marks < 2 mm. Use a low-power binocular microscope. |
| B | Carbon Smudge | Smudge width: ½ in (12 mm). Length: 2-3 in (51-76 mm). Support on plate glass. |
| C | Wetting | Apply water to observe structural differences in absorbency and openness. |
| D | Wetting and Charring | Charring after wetting reveals the wire pattern via differential fiber bonding. |
| E | Tearing | Assess the tear characteristics and fiber orientation between the two sides. |
| F | Marking with a Soft Metal | Rubbing a soft metal across the sheet highlights the wire knuckles. |
Procedure A — Direct Observation: Fold the specimen so both sides are simultaneously visible. Hold the specimen horizontally and direct light to strike at a very low angle (less than 10°). Vary the angle of illumination and rotate the sheet in a horizontal plane to highlight the wire marks. Look for rectangular or diamond-shaped impressions. Do not confuse the larger, irregular pattern of felt marks with the fine, regular wire marks, which are always smaller than 2 mm.
Procedure B — Carbon Smudge: Place a small piece of carbon paper between your thumb and middle or forefinger with the black surface against the paper. Using considerable pressure, slowly pull the carbon paper across the surface to produce a black mark about 12 mm wide and 51 to 76 mm long. Perform this on both sides of the specimen. The wire side typically picks up a sharper, more uniform impression of the distinct wire pattern.
⚙️ Significance, Use, and Best Practices
The wire and felt sides of a paper sheet typically differ in key physical and optical characteristics. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
💡 Best Practice Tip: If one procedure does not yield a definitive identification, do not hesitate to try the other procedures. The standard specifically validates that a clear result from any one of the six procedures is sufficient to establish the wire side of the paper.
❓ Frequently Asked Questions
🔍 What is the primary goal of ASTM D5039-97?
The standard provides standardized test methods for identifying the wire side of paper produced on a one-wire fourdrinier paper machine, differentiating it from the felt side.
💡 How is the Direct Observation test (Procedure A) conducted?
Fold the paper to view both sides. Illuminate it with light at an angle of less than 10°. Look for the fine, regular wire marks, which are always smaller than 2 mm. A low-power binocular microscope can assist in the observation.
⚡ What are the specific dimensions for a Carbon Smudge test (Procedure B)?
Using carbon paper under firm finger pressure, a black smudge is created. The resulting mark should be approximately ½ in. (12 mm) wide and 2 to 3 in. (51 to 76 mm) long, conducted on a smooth support surface like plate glass.
📌 Are these test methods applicable to all paper types?
No. The standard explicitly states these procedures are not applicable to paper made on cylinder, twin-wire, or other special machines. Results may also be ambiguous on coated, surface-treated papers, or high-grade specialty papers.