Frost formation and condensation in stone–wool insulations

This paper reports on a laboratory experiment concerning frost formation and moisture condensation in fibrous insulation based on stone–wool. Frost formation in samples of stone–wool open to air was noted in cases when temperature field over the specimen was between +20 and −20 °C and air on the warm side was saturated with moisture.Frost accumulated with time in the part of the specimen facing the cold air. In the part of the specimen facing the warm humid air condense formation occurred. In this part the material had moisture content considerably higher than what could be anticipated from data such as moisture isotherms.Border between frost and liquid condensate was quite sharp in the specimens of higher density. Moisture content mass by mass has an upward trend with decreasing density of the material sample. Moisture resistance factor was found to be quite high at these circumstances. Reason for this is not clear.