Heat attacks a label in three separate places: the adhesive softens and oozes or lets go, the face stock shrinks or yellows, and the printed image fades or chars. A construction can pass one and fail another, so we assess all three on the same sample.
Method
| Item | Condition |
|---|---|
| Substrate | Customer’s own substrate wherever possible; otherwise stainless steel or the specified plastic |
| Dwell before exposure | 24 h at 23 °C, 50 % RH |
| Exposure | Held at target temperature for 24 h, or the customer’s actual cycle |
| Assessed after exposure | Edge lift, adhesive ooze and residue, dimensional change, discolouration, print legibility, barcode scan |
Temperature bands and typical constructions
| Service temperature | Typical construction | Typical use |
|---|---|---|
| up to 80 °C | Paper or BOPP, standard permanent acrylic | Warm fill, warehouse and transport in hot climates |
| up to 120 °C | PP / PET face, high-temperature acrylic | Engine bays, lubricants, small appliances |
| up to 150 °C | PET or aluminium face, modified acrylic | Motors, powder-coat pre-bake, autoclave cycles |
| up to 260 °C, short cycle | Polyimide face, silicone or high-temp acrylic | PCB assembly and lead-free reflow |
These bands are indicative starting points for selection, not a specification. Peak temperature alone does not decide the construction — exposure time, the number of cycles, and whether the label is loaded or touched while hot matter just as much.
What to tell us
- Peak temperature and how long it is held
- Number of heat cycles over the product’s life
- Application temperature — labels are often applied cold and heated later
- Substrate material and surface condition, including any oil or release agent
- Whether the label must stay scannable after exposure
Related: Polyimide labels · Engine oil labels · Label Laboratory