Why thermal printouts aren’t a safe GxP record

Thermal receipt paper is convenient, cheap and everywhere in the lab. It’s also one of the least durable ways to keep a GxP record.

Balances, pH meters, refractometers and many other benchtop instruments print results on thermal paper. In many labs, that printout is taped into a notebook or attached to a batch record and treated as the original record. It’s a practical habit, and a real data integrity risk.

The problem with thermal paper

Thermal paper produces an image through a heat-sensitive coating rather than ink. That coating degrades. Heat, light, humidity, contact with plastic sleeves and adhesives, and even handling can cause printouts to fade, sometimes to the point of being unreadable within months.

GxP records often need to be retained for many years. A record that fades before its retention period ends fails the “Enduring” and “Available” principles of ALCOA+, and a faded printout may be the only evidence that a test was performed correctly.

What regulators expect

Regulators expect original records, or true copies of them, to remain complete, legible and accessible for the full retention period. If a thermal printout is your original record, you’re responsible for keeping it readable for that entire time, which in practice is very difficult.

Your options, from strongest to weakest

1. Capture the data electronically at the source

Many instruments that print to a receipt printer send that output over a serial or USB connection. That output can be captured directly into a controlled application, where it’s stored as an attributable electronic record with an audit trail. The electronic record becomes the original, and the printout becomes a convenience copy, or disappears entirely.

2. Print to durable media

Some instruments can be connected to a standard printer that uses plain paper and toner or ink. This doesn’t solve attribution or transcription risks, but it does remove the fading problem.

3. Create verified true copies

Where thermal printouts can’t be avoided, they can be converted into true copies: scanned or copied onto durable media, then verified as complete and accurate against the original. To hold up, a true copy process needs:

• A procedure that defines when copies are made, how, and by whom
• Verification that the copy is complete and legible, including all data and metadata
• A record of who verified the copy and when
• Copies made promptly, before the original has a chance to degrade

4. Make paper attributable

Where paper remains part of the record, a controlled stamp for signing and dating printouts at the time they’re produced or attached helps make them attributable and contemporaneous. It doesn’t fix fading, so it works best combined with one of the options above.

Don’t forget the existing archive

If thermal printouts have been your original records for years, check the oldest ones still within their retention period. If they’re fading, prioritize creating verified true copies now, while they’re still legible.