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D6487-10 – Standard Test Method Technical Guide
🖨️ Practice Overview and Applications
ASTM D6487-10 (Reapproved 2019) provides a standardized method for preparing prints of paste printing inks using a hand-operated laboratory flat-bed proof press. Initially developed by the National Printing Ink Research Institute, it is primarily used for creating single-color solid-area prints via the dry offset process (Letterset) on flat substrates like paper or metal. The practice can be adapted for direct letterpress printing.
This practice is applicable to lithographic and letterpress inks that dry by oxidation or penetration. With additional drying or curing equipment, it can also be used for heat-set or energy-curable inks. The procedure is designed to minimize variability within prints and among different operators, ensuring consistent results.
⚙️ Print Preparation Procedure
The print preparation involves several precise steps to ensure consistent ink transfer and print quality. First, the test ink is metered onto a brayer and rolled out evenly on a distribution plate following a specified pattern. The ink is then transferred to the printing plate. The substrate is clipped onto the impression plate, and the blanket cylinder is rolled over the inked plate exactly six times, followed by one pass over the substrate to complete the print.
The following table outlines the key steps in the print preparation process:
| 🔢 Step | ⚙️ Action | 📋 Description |
|---|---|---|
| 1 | Ink Metering | Apply test ink onto brayer using specified method |
| 2 | Distribution | Roll out ink on distribution plate in patterned sequence |
| 3 | Plate Inking | Transfer ink from brayer to printing plate |
| 4 | Substrate Mounting | Clip substrate onto impression plate securely |
| 5 | Transfer | Roll blanket cylinder over inked plate six times |
| 6 | Printing | Roll blanket cylinder once over substrate to complete print |
📊 Evaluation and Quality Control
After printing, the print is dried to the touch and evaluated for reflection density. The evaluation can be done instrumentally using a densitometer or visually by comparing to a standard reference print under specified viewing conditions (e.g., ANSI PH 2.30). The goal is to achieve a target reflection density that corresponds to the desired film thickness equivalence.
Table 2 lists the standards referenced in this practice for additional guidance and methods.
| 📄 Standard | 🔖 Description |
|---|---|
| D6073 | Test Method for Relative Setting of Heatset Printing Inks |
| D6846 | Practice for Preparing Prints of Paste Printing Inks with a Printing Gage |
| D7305 | Test Method for Reflection Density of Printed Matter |
| ANSI PH 2.30 | Viewing Conditions for Graphic Arts and Photography |
| CGATS.5 | Spectral Measurements and Colorimetric Computation for Graphic Arts |
💡 Tip: To ensure consistency, always follow the specified distribution pattern and use exactly six roller passes over the inked plate. This minimizes variability and ensures even ink transfer.
⚡ Important: This practice does not measure actual film thickness. Use reflection density comparisons as a proxy. Refer to Section 7 of the standard for safety precautions when handling inks and equipment.
❓ Frequently Asked Questions
🔍 How is the print evaluated after preparation?
The print is evaluated by its reflection density, measured instrumentally or visually compared to a standard reference print.
💡 What types of inks are suitable for this practice?
Suitable inks include lithographic and letterpress inks that dry by oxidation or penetration. With equipment modifications, it can be used for heat-set or energy-curable inks.
⚡ How many times is the blanket cylinder rolled over the inked plate?
The blanket cylinder is rolled over the inked plate exactly six times, followed by one pass over the substrate.
📌 Can this practice be used for direct letterpress printing?
Yes, while primarily for dry offset (Letterset), it can be readily adapted for direct letterpress printing as specified in the scope.