Acrylic, polyester, and other resins can be added during the paper making process to improve the internal bond strength of the paper. The paper is then printed and generally coated with polyurethane, urea, polyester, acrylic or melamine resins, or a combination thereof. Decorative foils are cellulose papers weigh between 40 and 140 grams per square meter untreated, although most of the commercially available papers in this category tend to range between 40 and 80 grams per square meter. These overlays may be impregnated or topcoated with melamine resins. Treating may add 20 to 40 grams of weight or more, depending on the basis weight of the paper.
Decorative foils require an adhesive for lamination.
In the United States they have been called melamine papers, intermediate weight foils, and impregnated foils. They are all of intermediate weight, but so are most of the saturated papers. Impregnation, or lack thereof, and the percentage of resin used, have a direct effect on the internal bond strength of the paper, as well as the porosity, cutting qualities, and machinability. These overlays are saturated with reactive resins, which are partially cured at the point of saturation. Final curing is done at the time of hot press lamination when the resins form a hard crosslinked thermoset material.