How can coating or impregnation change the properties of finished paper?

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Coating and impregnation are essential "wet converting" processes used to enhance the functional and aesthetic properties of paper for specific applications.1

Benefits of Coating

Coatings are primarily applied to improve the surface quality of paper, particularly for high-quality printing. Key benefits include:
* Printability: Coatings create a uniform surface that ensures better reproduction of printed images, including half-tone and color printing, while minimizing visible blemishes.1
* Aesthetics: These processes enhance the smoothness, gloss, and opacity of the paper or paperboard.1
* Efficiency: Coating allows for the use of more economical base paper stock by providing an "upgrading" effect that improves the final product's performance.1

Functional Enhancements

Beyond aesthetics, specialized coatings—such as the extrusion-coating of polyethylene—provide critical functional barriers. These treatments can render paper:
* Waterproof and resistant to water vapor.
* Resistant to grease and various gases.
* Stable and flexible, making it ideal for heat-sealed packaging that is free from odor and toxicity.1