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SOP for Detecting the PVDC-Coated Side of Blister Film

Last reviewed 29 Oct 2026 · 4 min read

Contents
  1. 1. Objective
  2. 2. Scope
  3. 3. Responsibility
  4. 4. Why the coated side matters
  5. 5. Procedure
  6. 6. Acceptance criteria
  7. 7. Training
  8. 8. Distribution
  9. 9. Records and retention
  10. Frequently asked questions
  11. Which side of PVC/PVDC film is the coated side?
  12. Can I use a roll if the test result is unclear?
  13. Why test again after a joint?
  14. Abbreviations
  15. References

In short: PVC/PVDC and PVC/PE/PVDC films are coated on one side only, and the coated side must face the correct way on the blister machine for the barrier to work. This example SOP shows how packaging staff confirm and mark the coated side of each roll, and what to do if it cannot be confirmed.

This is an illustrative template. Adapt it to your own quality system, film specification and site safety rules.

1. Objective

To describe how the PVDC-coated side of PVC/PVDC or PVC/PE/PVDC film is identified and marked before the roll is used for blister packing.

2. Scope

This example SOP applies to PVC/PVDC and PVC/PE/PVDC film rolls received for blister packing at the manufacturing facility.

3. Responsibility

  • Packaging officer/executive: performs the identification test and marks the roll as described below.
  • Head of Packaging: ensures the procedure is followed.
  • Quality Assurance: reviews deviations, rejections and the records.

4. Why the coated side matters

The PVDC layer is the moisture barrier. If the film is loaded with the coating on the wrong side, the blister may be sealed against the wrong surface and protection against moisture can be reduced. Identifying and marking the coated side at the start of the roll avoids this error. Packaging material handling and identification are part of the basic material controls expected under GMP; see also guidelines on packaging for pharmaceutical products.

5. Procedure

  1. Confirm the roll is released by QA and matches the approved film specification (material, thickness, lot number).
  2. Remove the outer polybag cover of the roll.
  3. Cut a small test piece from the start of the roll, at the end that would be wasted.
  4. Carry out the approved identification test for the coated side, following the method and chemical safety instructions of your site. Wear the protective equipment required by the safety data sheet (SDS) of any chemical used, such as goggles and gloves, and work in the area designated for the test.
  5. Mark the confirmed coated side on the roll as defined in your SOP (for example an “OUTER SIDE” or “COATED SIDE” sticker at the roll end) so the operator loads the film the right way.
  6. If the first side does not give the expected result, test the second side. If neither side gives the expected result, do not use the roll; reject it and inform QA.
  7. If a roll has a joint, repeat the check on film after the joint, because the orientation may differ across the splice.
  8. If the test fails at any position, cut a piece from the roll at that position and test the opposite side. If neither side meets the criterion, the remaining roll is quarantined for QA decision.
  9. Dispose of test pieces and any chemical waste as per the site’s hazardous-waste procedure.
  10. Record the roll lot number, result, date and the name of the person who performed the test.

The exact reagent, its handling and the colour change are not described here. Use only the method in your approved material specification or supplier documentation, and follow the SDS and your site’s Environment, Health and Safety (EHS) procedure for that chemical. Do not prepare or handle test chemicals without that approval.

6. Acceptance criteria

The coated side is identified and clearly marked on the roll. A roll where the coated side cannot be confirmed is rejected or held for QA decision. These criteria are an example in-house criterion.

7. Training

  • Trainer: Head of Packaging or designee.
  • Trainees: Packaging and QA staff.

8. Distribution

Controlled copies to QA and Packaging; the master copy is retained by QA.

9. Records and retention

Keep the identification records with the packaging records of the batch. Batch-related records are kept at least 1 year after the expiry date of the respective product batch (EU GMP Part I Chapter 4 §4.11; 21 CFR 211.180(a)), or longer if local law or the marketing authorisation requires.

Frequently asked questions

Which side of PVC/PVDC film is the coated side?

It differs between suppliers and rolls, which is why the side is confirmed and marked on each roll rather than assumed.

Can I use a roll if the test result is unclear?

No. Hold the roll and refer to QA. An unconfirmed roll risks a poor moisture barrier.

Why test again after a joint?

A splice can join film with a different orientation, so the check is repeated after it.

Abbreviations

PVC: polyvinyl chloride. PVDC: polyvinylidene chloride. PE: polyethylene. SDS: safety data sheet. EHS: environment, health and safety. QA: quality assurance.

References

  1. European Commission, EudraLex Volume 4, Part I, Chapter 4 “Documentation”, §4.11 (retention of records).
  2. US FDA, 21 CFR 211.180(a) (record retention).

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