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Permeability of coatings for water and water vapor is an important factor in their wood protective function. In this study, the permeability of coatings in terms of liquid water and water vapor absorption and desorption was measured based on different parts of the standard EN 927. This study evaluated the permeability of commercial coating systems and ascertained effects of coating layering on the coating permeability. For this measurement, six different waterborne acrylate dispersions were used as paint on spruce test samples. The results clearly revealed that liquid water and water vapor uptake were affected by coating film thickness, number of coats, and coating composition (producer). It was ascertained that the type of coating pigmentation affected water absorption of coatings and that with a constant coating film thickness, the number of coats affected water vapor absorption and desorption, but not water absorption. Furthermore, it was observed that the number of coats affected the correlation between the coating film thickness and water vapor absorption and desorption. The values for water vapor absorption were much higher than for liquid water absorption and, unlike the water vapor absorption rate, the water vapor desorption rate was approximately 50% lower.

This study aimed to evaluate the effect of size press coating on two types of recycled papers using different types of nanofibrillated cellulose (NFC) and cationic starch (CS) on physical and mechanical properties. Wheat straw was used as a cellulose source, and NFC was obtained through oxidative and enzymatic pretreatments. Recycled fluting and coreboard papers were coated with cationic starch/NFC blends at various concentrations of NFC (0.5%, 1%, 2%, 3%, and 4%) using a three-time repetitive size press application, followed by one-time drying section, and compared to uncoated papers. The application of a coating suspension containing 4% periodate-oxidized NFC on both paper surfaces resulted in a significant improvement in the tensile index, burst index, and internal bond strength of the papersheets, with increases of up to 60.6%, 96.3%, and 119.9%, respectively. Furthermore, significant decreases in air permeability were also observed with reductions of 75% and 81.6% for coreboard and fluting papers, respectively. Compared to other pretreatment methods, periodate oxidation resulted in higher viscosity values in NFC samples. Therefore, the application of periodate-oxidized NFC with a size press resulted in a significant improvement in the mechanical and barrier properties of papers made from recycled pulps.

The printability properties of the paper can be increased by some processes applied to the surface. The use of non-recyclable materials derived from petroleum is decreasing day by day, and the demand for recyclable materials obtained from renewable sources is increasing. These materials include cellulose derivatives, starch types and polyvinyl alcohol. The materials ratios, sizes, physical and chemical properties of these materials used in the processes applied to the paper and the content of the paper will affect the strength of the paper as well as change the surface properties and signi cantly affect the printability.In this study, uting and core board papers coated with different amounts of cellulose nano ber/ cellulose nano ber-oxidized (CNF/CNF-OX) were produced. Surface properties, contact angle, surface energy, color and gloss of the produced papers were measured by optical microscope, goniometer, spectrophotometer and glossmeter. The papers were printed with the IGT C1 offset printability tester. The color and gloss properties of the printed papers were measured. As a result, in terms of printability, it was determined that CNF/CNF-OX coated papers have smoother surfaces and give better results in terms of both gloss properties and printability.