Label Curl & Cupping: Common Issues for Printing & Automatic Labelling and Solutions

Label curl and cupping are frequent issues for customers using thermal transfer printers and automatic labellers. Curled labels cause printer jams, print head damage, labeller stoppages and label edge lifting after application, resulting in production downtime and complaints.

Curl and cupping are not simple printing defects. They are material deformation caused by unbalanced stress, moisture and temperature between facestock and liner. We offer four types of release liners: glassine, PET, CCK and PEK, each with different properties and curl risks.

1. Two types of curl

Curl: The label bends upward or downward; edge curl is most common.

Cupping: Bowl-shaped deformation, often seen on small film labels.

2. Main causes

Improper liner selection

We normally use 80gsm White Glassine liner which can help to print smooth, while some suppliers may use 60gsm to save cost but will have risk of curling when printing.

PET liner: dimensionally stable and moisture-proof, but easy to cup if matched incorrectly

CCK liner: coated kraft liner, moderate moisture resistance, prone to curl under humidity change

PEK liner: special composite liner for high-temperature applications; improper matching leads to curl

3. Our verification process before production

Conditioning test under different temperature and humidity

Thermal transfer printing simulation test for glassine liner

Unwind & rest test to check delayed curl

Curved surface application test for spring-back

Custom rewinding tension for glassine / PET / CCK / PEK

Recommend suitable liner according to your application; 80gsm glassine is preferred for printing

4. Tips for customers

Choose 80gsm white glassine for thermal transfer printing; avoid 60gsm glassine

Use flexible facestock for small curved containers

Keep glassine and CCK rolls moisture protected during transit and storage

Adjust printer temperature, stripper angle and roller pressure