In the market of the Latvia different wood surface coating materials suitable for use in outdoor conditions are offered, but available information on the efficiency of these against direct water exposure is insufficient. For structural timber building elements, such as glued laminated timber (GLT), the surface coating should be applied taking into account technological, visual or colour changes (ISO 7724:1984) and – last, but not least – economic aspects are considered. Wood surfaces coated with coating materials, such as varnishes, paints, etc. can stabilize some properties such as movement of moisture content, dimensional changes and attack by microorganisms and fungi. The changes in the moisture content of timber may influence such important parameters as mechanical properties and the total life time of the structural timber elements. A study has been conducted with the aim of assessing the efficiency of coating materials used for wood protection against water absorption. In this study, six different commercial coating products used for the treatment of spruce (Picea Abies L. Karst.) and pine (Pinus Sylvestris L.) samples were tested. The efficiency of different coating substances was assessed using two modified test methods according to the standards EN 382-2 (1994) and EN 927-5 (2006), determining the surface water absorption after immersion in water for 24 h and the dynamics of water absorption of the glued laminated timber for 696 h kept in water. As a result of the study, it has been ascertained that organic solvent-based commercial coating products are more efficient against short-term and long-term wood water absorption compared to oil-based coating materials.

Durum wheat (Triticum turgidum) is used for the production of various ready-to-eat products such as breakfast cereals, puffed grains, and extruded products. Technological processes of grain processing and the addition of different ingredients cause changes in the physical and chemical properties of the product, which give puffed grains a unique porous structure and change their nutritional value. This study aimed to evaluate the effect of coating on the physico-chemical characteristics of puffed wheat grains depending on the coating material. The study revealed that the application of coating increased dry matter and thousand-kernel weight (TKW). Water activity decreased in puffed grain without coating (BZ), and puffed grain with whey powder (MC) compared to wheat grain. The reduction in the moisture content increased the crispiness of product. Application of coating led to a decrease in the hardness of both MC and puffed wheat grain with vanillin and sugar (BV). Applying additives to the product’s surface led to a decrease in the water absorption index (WAI). The water solubility index (WSI) increased in the MC and BV samples. Samples BZ, BV and MC had higher L* (lightness) values than wheat grains because the puffing process expanded the cells, confirmed by scanning electron microscopy, and caused starch gelatinisation. The a* (redness) value of wheat was greater than that of BZ, BV and MC, which may be due to the partial removal of the outer layer of wheat grains. The milled samples of BZ, BV and MC were slightly darker, having lower L* values, compared to unprocessed wheat grain.