Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
CAN/CGSB 131.10-2017: Technical Specifications and Compliance for Silver-Gelatin Microfilm Manufacturing and Processing
Understanding the Canadian Standard for High-Quality Microfilm in Document Imaging and Archival Systems
The CAN/CGSB 131.10-2017 standard, published by the Canadian General Standards Board (CGSB), establishes comprehensive requirements for the manufacturing and processing of silver-gelatin type microfilm. This standard is widely referenced in Canadian government and industry applications for creating microforms that meet strict archival and reproduction quality criteria. It aligns with international frameworks such as ISO 18901 and ISO 18902 while addressing specific Canadian needs, including environmental storage conditions and testing protocols. This article provides a detailed overview of the standard’s scope, technical requirements, implementation guidance, and compliance considerations.
Scope and Application
Documents Covered
CAN/CGSB 131.10-2017 applies to silver-gelatin microfilms used for the microfilming of documents, engineering drawings, and other graphic materials. It covers both camera original negatives and duplication intermediates intended for permanent records. The standard specifies requirements for film properties such as density, resolving power, processing quality, and archival permanence. It does not apply to diazo, vesicular, or other non-silver microfilm types, nor to colour microfilm.
Types of Microfilm
The standard addresses film formats in 16 mm and 35 mm widths, as well as microfiche and aperture cards produced from silver-gelatin film. It covers both first-generation (camera negatives) and subsequent generation (duplicate) films. The requirements apply regardless of whether the film is used in a roll form, cut into strips, or mounted in aperture cards.
Technical Requirements
Key Performance Parameters
Table 1 summarizes the principal technical requirements specified in CAN/CGSB 131.10-2017. These parameters ensure that the microfilm meets quality thresholds for readability, durability, and archival life.
| Parameter | Requirement | Test Method Reference |
|---|---|---|
| Minimum D-max (background density) | ≥ 1.10 for negative originals; ≥ 1.00 for duplicates | ISO 5-2, ISO 5-4 |
| Maximum D-min (base plus fog) | ≤ 0.10 for unexposed, processed film | ISO 5-2, ISO 5-4 |
| Resolving power (minimum) | 170 lp/mm for camera negative; 130 lp/mm for duplicates | ISO 12233 or ISO 3334 |
| Residual thiosulfate ion concentration | ≤ 0.014 mg/cm² (archival); ≤ 0.03 mg/cm² (non-archival) | ISO 18902 (methylene blue method) |
| Granularity (RMS) | ≤ 10 × 10⁻³ at a density of 1.0 | ISO 5-3, ISO 18901 |
| Maximum coating hardness (after processing) | No damage when abraded per specified test | Annex A of the standard |
| Edge splice strength | ≥ 70 % of base film tensile strength | ASTM D882 |
Processing Chemistry
The standard mandates that all processing be carried out using developer and fixer formulations that are compatible with silver-gelatin emulsions. The developer must be a standard black-and-white developer (e.g., D-76 or similar) with controlled pH, temperature, and agitation. The fixer must be an ammonium- or sodium-based thiosulfate solution with a hardener to ensure mechanical stability. After fixation, the film must be thoroughly washed to reduce residual thiosulfate to the levels shown in Table 1.
Tip: For archival applications, it is recommended to maintain the residual thiosulfate level below 0.014 mg/cm² even if the film is classified as “non-archival” in the records management plan. Testing should be performed within 8 hours of processing to obtain accurate readings.
Implementation Highlights
Manufacturing Quality Control
CAN/CGSB 131.10-2017 requires film manufacturers to implement a quality management system that includes ongoing monitoring of physical properties. Each batch must be tested for D-min, D-max, resolving power, and residual thiosulfate. The standard also specifies that a strip of unexposed, processed film from each batch be retained for at least one year for reference.
Processing Equipment
The standard does not prescribe specific equipment brands, but it requires that all processing be performed in a clean, well-ventilated room with controlled temperature (20 ± 2 °C) and relative humidity (40 %–60 %). Developer temperature must be maintained within ± 0.3 °C of the recommended value. Developer replenishment rates should follow the chemical manufacturer’s recommendations to maintain consistent activity.
Important: Inadequate washing is the most common cause of non-compliance with the residual thiosulfate requirement. Operators should periodically replace wash water and verify flow rates to ensure effective thiosulfate removal.
Handling and Storage
Processed microfilm must be stored in accordance with the conditions outlined in the standard. For archival life expectancy (LE-500), film should be stored at a temperature ≤ 21 °C and relative humidity between 20 % and 50 %, with a minimum dew point of 2 °C. Polyester-base films are preferred for long-term storage due to their dimensional stability. Microfilm should be stored in acid-free, lignin-free enclosures and kept in a dark environment to prevent photo-chemical degradation.
Compliance Notes
Testing and Certification
Compliance with CAN/CGSB 131.10-2017 is typically verified by an accredited laboratory. The testing includes density measurements using a calibrated densitometer conforming to ISO 5, resolving power determination using a test target (e.g., NBS 1010a or ISO 12233), and residual thiosulfate analysis via the methylene blue method specified in ISO 18902. Film hardness and splice strength are tested using the methods described in the standard’s annexes.
Certification Ready: Many microfilm service providers in Canada include CAN/CGSB 131.10 compliance as part of their quality assurance. Request a certificate of compliance from your film supplier to confirm adherence to the latest 2017 edition.
Common Non-Conformities
- Low resolving power: Often caused by improper focus, vibration, or inappropriate aperture settings during exposure. Verification with a test target every camera setup is recommended.
- High residual thiosulfate: Usually results from insufficient wash time, low wash water temperature, or exhausted fixer. Fixer silver loading should be monitored regularly.
- Poor D-max uniformity: Can be due to uneven developer temperature or poor agitation. Process control strips should be run at least once per operator shift.
- Base fog above D-min limit: May indicate outdated film, excessive exposure to light, or contaminated developer. Check film expiration dates and storage conditions.
Critical: Failure to meet the residual thiosulfate requirement can lead to image fading within a few years, making the film unsuitable for archival records. Always perform chemical testing after processing, especially if using a new batch of fixer or after a machine service.
Transition from 2002 to 2017 Edition
The 2017 edition of CAN/CGSB 131.10 introduced several updates, including relaxed tolerances for duplicate film resolution, additional guidance for automatic processing equipment, and more explicit storage requirements based on ISO 18902. Users of the earlier 2002 edition should review the new annexes regarding long-term storage and handling to ensure continued compliance.
Frequently Asked Questions
Q: Is CAN/CGSB 131.10-2017 mandatory for microfilm used in Canadian government agencies?
A: Yes, many federal and provincial departments require microfilm to meet this standard for records with archival or legal significance. Contract specifications often reference the standard directly.
A: Yes, many federal and provincial departments require microfilm to meet this standard for records with archival or legal significance. Contract specifications often reference the standard directly.
Q: Does the standard apply to microfilm produced by digital-to-film recorders (computer-output microfilm, COM)?
A: CAN/CGSB 131.10-2017 primarily covers conventional camera filming. However, it may be applied to COM films if they are silver-gelatin based and meet the same density and resolution criteria. Some specific COM characteristics (e.g., character generation) are not covered, so additional testing may be needed.
A: CAN/CGSB 131.10-2017 primarily covers conventional camera filming. However, it may be applied to COM films if they are silver-gelatin based and meet the same density and resolution criteria. Some specific COM characteristics (e.g., character generation) are not covered, so additional testing may be needed.
Q: How often should residual thiosulfate testing be conducted?
A: The standard recommends daily testing for high-volume processing operations and at least weekly for lower volumes. When any processing variable changes (e.g., new fixer batch, wash water temperature shift), immediate testing is advised.
A: The standard recommends daily testing for high-volume processing operations and at least weekly for lower volumes. When any processing variable changes (e.g., new fixer batch, wash water temperature shift), immediate testing is advised.
Q: Can alternative test methods be used instead of the methylene blue method?
A: Yes, the standard recognizes the silver densitometric method (ISO 18902 alternate) as equivalent, provided its accuracy is verified against the methylene blue method. However, for certification purposes, the methylene blue method remains the reference.
A: Yes, the standard recognizes the silver densitometric method (ISO 18902 alternate) as equivalent, provided its accuracy is verified against the methylene blue method. However, for certification purposes, the methylene blue method remains the reference.
© 2026 — This article is intended for informational purposes and does not replace the official CAN/CGSB 131.10-2017 document. For definitive compliance, refer to the current edition published by the Canadian General Standards Board.