Many factors affect ageing of plasters and mortars. Besides the age of the structure they are composition of mortars and plasters, stage of matrix hardening, position in the structure, type of building material, climatic conditions, capillary elevation of ground water, level above ground, azimuthal orientation, insulation of structure, quality of maintenance, reconstructions, utilization of object etc.
Decreasing of quality of outer parts of structure is first result of ageing.
Plaster alters its texture, color, hardness and cohesion with wall construction
material are decreasing and during the latest period parts of plaster peel off
and fall down. Plaster does not supply protection and aesthetic function.
Employees of Museum in Ostrava offered the best structures for study. They are
churches in Ostrava (Saint Wenceslas) and Brantice (Translation of Virgin Mary).
Medieval core of Saint Wenceslas church forms polygonally closed presbytery,
outer walls and square shaped Western Tower. Author of building historical project
D. Líbal supposes construction phase during second half of 14th century.
Archaeological research (V. Sikulová) during 70’ discovered relicts of basement of
walls in presbytery and in both aisles, which belong to former construction phase
at the end of 13th century eventually in the beginning of 14th
century. Archaeological research in 1998 discovered basement of originally Gothic
sacristy built during the second construction phase and relicts of foots of columns.
Columns probably held up flat beam ceiling up to 16th century when nave and
aisles were covered by vault.
Samples of mortar of Saint Catherine church in Kelč were taken from outer side of
presbytery basement. It was built according to archive data in 80’ of 16th
Mortars and plasters represent collection of samples of church of Translation of
Virgin Mary in Brantice.