White Lined Chipboard, also referred to as: WLC, GD, GT or UD.

This grade of paperboard

Paperboard

Paperboard is a thick paper based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker than paper. According to ISO standards, paperboard is a paper with a basis weight above 224 g/m2, but there are exceptions. Paperboard can be single...

 is typically made from layers of waste paper

Paper recycling

Paper recycling is the process of recovering waste paper and remaking it into new paper products. There are three categories of paper that can be used as feedstocks for making recycled paper: mill broke, pre-consumer waste, and post-consumer waste. Mill broke is paper trimmings and other paper...

 or recycled

Recycling

Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...

 fiber

Fiber

Fiber is a class of materials that are continuous filaments or are in discrete elongated pieces, similar to lengths of thread.They are very important in the biology of both plants and animals, for holding tissues together....

s. Most often it comes with two to three layers of coating

Coated paper

Coated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...

 on the top and one layer on the reverse side. Because of its recycled

Recycling

Recycling is processing used materials into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution and water pollution by reducing the need for "conventional" waste disposal, and lower greenhouse...

 content it will be grey from the inside.
The main enduse for this type of board

Paperboard

Paperboard is a thick paper based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker than paper. According to ISO standards, paperboard is a paper with a basis weight above 224 g/m2, but there are exceptions. Paperboard can be single...

 is for packaging of frozen

Frozen food

Freezing food preserves it from the time it is prepared to the time it is eaten. Since early times, farmers, fishermen, and trappers have preserved their game and produce in unheated buildings during the winter season. Freezing food slows down decomposition by turning water to ice, making it...

 or chilled food

Chilled food

Chilled food is prepared food that is stored at refrigeration temperatures, which are at or below . The key requirements for chilled food products are good quality and microbiological safety at the point of consumption...

, cereals, shoes, toys

Toys

Toys is a 1992 comedy film directed by Barry Levinson and starring Robin Williams, Michael Gambon, Joan Cusack, Robin Wright, LL Cool J, and introducing Jamie Foxx as Baker. The film failed at the box office at the time of its release, despite its impressive cast and lavish filmmaking. Levinson was...

and others.

Health risks have been associated with using recycled material in direct food contact. Swiss studies have shown that recycled material can contain significant portions of mineral oil, which may migrate into packed foods. (Mineral oil levels of up to 19.4 mg/kg were found in rice packed in recycled board.)