Treat three-proof as a commercial description that needs an agreed list of properties and test conditions. Water, oil and rubbing should be assessed explicitly; alcohol or another cleaner is an additional named requirement, not an automatic promise.
Choose from the actual coating grade, print settings, adhesive and working station. A TOP or three-proof name does not establish a fixed reading life or mean every exposure is covered.
1. Turn the name into separate requirements
List liquids, rubbing, heat, light and contact materials encountered at the station. Record concentration, time and repetition where applicable.
Ask what the supplier means by the description and what the selected grade has been tested against. Do not assume all topcoats form one universal performance ladder.
2. Test the printed grade on the actual machine
Use the real printer, settings, artwork and supply format. Keep an unexposed printed reference and compare density, fine text and barcode readability after the relevant contact.
A changed or disappearing image can have more than one cause. Check the exposure record, coating, printing and storage rather than diagnosing alcohol from appearance alone.
3. Build a station-specific sample card
The table lists observations to make. It assigns neither an expected number of months nor an automatic best grade to a station.
| Station task | Exposure to record | Sample acceptance |
|---|---|---|
| Weighing and packing | Condensation, handling and application surface | Readable code and a retained bond |
| Oily handling | Actual oil, contact time and rubbing | Image, coating and edges after contact |
| Cleaning or sanitiser | Named liquid, concentration and wiping sequence | Results for that specific contact |
| Storage and despatch | Light, heat, contact materials and reading period | A grade-specific image and adhesion result |
4. Include bond and required reading period
Separate coating performance from adhesion to a chilled or damp package. Record the application surface and service conditions as well as print protection.
State the required reading period and storage exposure, then compare matching grade evidence and trials. A calendar threshold alone does not decide direct thermal versus thermal transfer; receipt paper is also a different, non-adhesive consumable.
BPA-free, BPS-free and phenol-free: ask for the scope
These descriptions are not interchangeable. A BPA-free statement does not establish that BPS is absent; a BPS-free statement does not establish that all phenolic developers are excluded. Ask the grade supplier how it defines a phenol-free claim and which substances, limits and assessment method its evidence covers.
- Record whether it covers the thermal coating, facestock or complete converted label.
- Food-contact suitability needs its own assessment for the intended contact conditions.
- Specify chemical requirements separately from water, oil and abrasion checks. “Triple-proof” does not establish BPA-free, BPS-free, phenol-free or food-contact suitability.
Koehler's thermal-paper portfolio distinguishes BPA-free and phenol-free options (checked 2026-11-05). This terminology guide does not assign either claim to an unspecified Bofmat product grade.
FAQ
Does three-proof always include alcohol resistance?
Do not assume that. Agree the claimed properties and request a separate test for the named alcohol or cleaner where needed.
Does TOP mean it will last longer in every use?
No. Compare the actual coating grade, printing and exposure evidence; a grade name alone is insufficient.
Why did the image disappear?
Record what touched it and inspect the print and coating against a reference. Appearance alone cannot identify one chemical or failure cause.
How long will the print remain readable?
Specify the required period and storage, contact and handling conditions, then assess matching grade information and samples. Do not use a universal month or year limit.
References and next steps
References illustrate material, process or verification distinctions; they do not establish a rating for a quoted Bofmat grade. Checked 2026-11-04.
Related: waterproof labels · Thermal label range · White direct-thermal labels · Three-proof thermal labels: confirm the grade · Receipt paper: a separate non-adhesive consumable · Printing-route selection · Cold-chain printing and reading
Send the actual surface, equipment, process and acceptance requirements to discuss a trial.