## 3 Results and Discussion
Effect of Accidental Wetting of Wood on the Mould Growth Development at 'Clean' Conditions (Experiment II)  
Wood as a hygroscopic material readily absorbs water when comes in contact with liquid water unless the surface is protected by coating. Liquid water penetration into wood is a complex process governed mainly by capillary forces and diffusion [39; 40]. The amount of the absorbed water depends mainly on the contact time and the rate of the water absorption, which depends on a number of factors such as principal direction of the surface, wood species, density, anatomical structure including peculiarities of intercellular connections and ratio of bordered pit aspiration, etc. [41; 42; 43; 44; 45; 46; 47; 48; 49; 50]. On the other hand, desorption is a reversed process, which starts immediately in an environment with RH < 100%. Desorption rate depends mainly on the environmental conditions (RH and temperature), and the rate of evaporation is the limiting factor of the process [51; 52]. It is well established that absorption and desorption isotherms do not follow the same curve resulting in sorption hysteresis with dissimilar EMC for equal environment (RH and temperature) [53]. Changes in wood MC of 'Dry' and 'Wet' specimens after placing them into the sealed mould test containers with the corresponding RH and temperature are presented in Figure 3.  
The mass of specimens increased by 25 \(\pm\) 5% on average due to water absorption during immersion. However, the moisture content (MC) gradient is formed with high MC levels next to the surface and steep decrease in the direction away from the surface [40; 41; 44; 46; 47]. Therefore, the MC determined for a wetted wood material provides only information about the average MC, which may greatly differ from the MC of the surface layer before the EMC is reached. It can be seen that the EMC for both tested RH levels was considerably higher for 'Wet' specimens (circles) than 'Dry' specimens (triangles). An exception was the environment of RH 91% and temperature 30 \({}^{\circ}\)C, when the difference between the EMC of 'Dry' and 'Wet' specimens was only 0.5%. In addition, higher EMC was detected for the 'Wet' specimens when drying took place at lower temperature, especially in the case of RH 91%, when the difference between EMC of the 'Wet' specimens held at 10 \({}^{\circ}\)C and 30 \({}^{\circ}\)C was more than 6%. No difference in EMC was observe between the 'Dry' specimens depending on temperature. This agrees with the finding that changes in temperature do not affect adsorption isotherm while desorption isotherm for higher temperatures is moved to the right resulting in lower EMC for a given constant RH [53; 54]. Generally, the main consequence of the wood wetting was higher EMC compared with 'Dry' specimens under similar conditions. However, considerable effect of the wood wetting on the mould growth was only observed for the specimens exposed to the lowest tested temperature (10 \({}^{\circ}\)C), when significantly higher rate of mould germination as well visible mould growth was detected for the 'Wet' specimens (Figure 4). For other conditions, no differences in the mould development were observed between the 'Dry' and 'Wet' specimens suggesting that accidental wetting of wood does not affect mould development at these conditions. This agrees with the finding of [PERSON] et al. (2012) that mould growth rate on pine sapwood is considerably more influenced by RH at a temperature of 10 \({}^{\circ}\)C compared with 22 \({}^{\circ}\)C [55]. Wood drying includes two interrelated processes that may have certain effect on the environment nearby the surface. Evaporation of water is an endothermic process causing decrease in temperature, on the one hand. The difference of 0.6-1.0 \({}^{\circ}\)C in surface temperature between 'Dry' and 'Wet' specimens was found by measuring the surface temperature with an infrared thermometer during the initial stage of the test of similar conditions (results not presented).