Label specifications explained: core size, winding and leading edge

Core size

The inside diameter of the cardboard tube the labels are wound on. Common sizes are 25 mm, 40 mm and 76 mm (3 inch). It must match the label applicator or printer, so ask your filler or packer before you order.

Outside diameter

The largest roll diameter the applicator can hold, for example 250 or 300 mm. It sets how many labels fit on one roll. Bigger rolls mean fewer changeovers, but only if the machine takes them.

Winding direction and leading edge

The leading edge is the edge of the label that comes off the roll first. Printers describe it with wind positions 1 to 8. Positions 1 to 4 are wound out, with labels on the outside of the roll: 1 is top edge first, 2 bottom edge first, 3 right edge first and 4 left edge first. Positions 5 to 8 are the same but wound in, with labels on the inside. The right position depends on how your applicator presents the tub or bottle, so get it from the person running the line.

Gaps, material and finish

• Gap: the space between labels on the roll, usually about 3 mm. The applicator's sensor needs a consistent gap.
• Material: paper, white or clear polypropylene. Film suits tubs and bottles that get handled or chilled.
• Finish: varnish or lamination protects the print. Mandatory information has to stay legible and indelible for the life of the product.
• Adhesive: choose one rated for your container material and any curve.

Before you order

Check the artwork itself too. A label that runs perfectly is still a problem if the supplement statements are missing or the small print is under 1.2 mm. Check your tub label or bottle label before it goes to print.