MG paper with enhanced barrier properties are called Glassine and Greaseproof papers.
Similar to the process of making MG paper, Glassine paper is produced by extensive chemical refinement of pulp to create a sheet with very low porosity within the fibers. This sheet is then super-calendared to further improve the density and orientation of fibers to create the glassine paper. The process of super-calendaring involves pressing and drying the paper web through a stack of alternating steel and fiber-covered rolls (called a super-calendar) at the end of the paper machine so that the paper fibres flatten facing in the same direction. Glassine paper is very thin and smooth and air and water resistant. It is translucent unless dyes are added to color it or make it opaque. It is used in foodservice as a barrier between strips of products (for example: meat, baked goods). Glassine is resistant to grease and facilitates separation of individual foodstuffs. Glassine is used as a base paper for making greaseproof paper.
The glassine is treated with starches, alginates or CMC in a size press to fill the pores between the fibres or treated chemically to make it fat repellent and greaseproof. Thus Greaseproof paper is impermeable to oil or grease and is used in cooking or food packaging. Greaseproof papers are used to carry or wrap meat and other food products. The food does not stick to the paper and the paper does not become soggy or weak. The greaseproof paper is permeable to air and moisture vapour which makes it possible for the food to breathe and steam and exhale excess moisture. These papers can also be used for carrying mince, as interleavers to separate burgers, chops and other meats, and as baking sheets for pastries, cakes and other foods. They can also be used to wrap and line cheese packages, fast food and many other products. Waxed greaseproof paper are used for bakery, cheese and other foods.