DOI Artikel:
Stępień, Piotr: Problemy technologiczne konserwacji fortyfikacji kleszczowych Wawelu
DOI Seite / Zitierlink: https://doi.org/10.11588/diglit.19894#0130
TECHNOLOGICAL PROBLEMS POSED IN CONSERYATION OF THE WAWEL TENAILLE FORTIFICATIONS
Sum m ary
The architectural study of the tenaille fortifications deter-
mined the conservators' tasks - the restoration of the loopholes
and of the original colouring in the oldest part of the walls,
dating from the end of the 18th century. In order to carry
them out it was necessary to solve a number of technological
problems not encountered in the conservation of other Wawel
objects.
The most conspicuous damage done to the bricks was their
dirtiness and disintegration - powdering and flaking which in
places even led to deep losses of materiał. Examination of the
structure revealed detachment of the face from the rest of the
wali. The main destructive element is water, whose penetration
is facilitated by the sloping face, the situation of the fortification
on the west side of the hill (prevalent west winds, the vicinity
of the Vistula), and leakage. The movement of moisture causes
transportation of soluble salts, their accumulation in the wali
structure, and their graining out on the surface. AJthough the
salt content in the wali is not high, the total amount of salt
runs to several tons. The simultaneous occurrence of various
kinds of salt which can react with one another is an additional
negative factor.
The next technological problem was posed by the wali
materiał itself. The parts dating from the end of the 18th
century were made of brick and lime-sand mortar; for the
bartizans specially moulded brick was used that would conform
with the curvature of the face. The wali face in this phase
was covered with a fairly thin coat of lime-sand floated plaster
coloured red. The brick used for 19th centuiy additions to the
wali differed in size from that present in the earlier phase;
the wali was pointed with lime mortar with a brick-powder
filier. In the 20th centuiy the wali was jointed with cement
mortar. This accelerated damage to the brick owing to the
obstruction of evaporation through joints.
Following the analysis, it was accepted that at the present
stage of eonservation theory and practice it would be impossible
to extract soluble salts from the entire wali substance; nor
would it be possible to convert the salts into an insoluble
form on account of the presence of nitrates. Only desalination
in the places of salt concentration was contemplated with a
view to its reduction to average level. It was accepted as a
basie line of counteraction to prevent salt accumulation by
reducing water migration within the wali substance - in the
first place by repairing the leakage, an adeąuate solution for
damp insulation, and application of diy methods of cleaning
the face. The hydrophobisation of the extemal face was con-
sidered too hazardous and not very effectiive. Such a treatment
would be advantageous in respect of the effect of rainwater
on the sloping outer face, but it might lead to salt accumulation
under the hydrophobised layer and in conseąuence to the
flaking of that layer. However, hydrophobisation was accepted
for the inner face and the coping of the parapet, that is, the
places of water penetration.
A slightly different procedurę was chosen for the bartizans.
The character of the objects (moulded brick) reąuired strict
conservation treatment, with as much authentic materiał as
possible preserved. The damaged bricks were not replaced,
instead the losses being replaced with mortar. As the bartizans
are not exposed to the inflow of water from the inside,
desalination and hydrophobisation of the whole surface was
considered advisable.
The reconstruction of floated plaster on the face of 18th
centuiy phase walls presented a specific technological problem.
As the original technology was not durable, it had to be
modified so as to ensure the lasting qualities of the floated
plaster; in other words, reconstruction of its original appearance
using a new technology was assumed. On the basis of inves-
tigations and practical tests the composition of the floated
plaster was established: slaked lime and low-alkaline cement
as joints, brick powder and granular glass-making sand as
fillers, pigments, and a synthetic modifier inereasing adhesion,
plasticity, and frost-resistance (hydrous dispersion of synthetic
resins, non-hydrophobic).
The first stage of work in the years 1993—1994 was carried
out on arms E and F. The experience gained at that stage
served to coiTect the technological assumptions; in 1995 arms
G and H were treated following these directions. Conservation
of the remaining ten arms is planned for the subseąuent years
of the large-scale restoration of Wawel.
Sum m ary
The architectural study of the tenaille fortifications deter-
mined the conservators' tasks - the restoration of the loopholes
and of the original colouring in the oldest part of the walls,
dating from the end of the 18th century. In order to carry
them out it was necessary to solve a number of technological
problems not encountered in the conservation of other Wawel
objects.
The most conspicuous damage done to the bricks was their
dirtiness and disintegration - powdering and flaking which in
places even led to deep losses of materiał. Examination of the
structure revealed detachment of the face from the rest of the
wali. The main destructive element is water, whose penetration
is facilitated by the sloping face, the situation of the fortification
on the west side of the hill (prevalent west winds, the vicinity
of the Vistula), and leakage. The movement of moisture causes
transportation of soluble salts, their accumulation in the wali
structure, and their graining out on the surface. AJthough the
salt content in the wali is not high, the total amount of salt
runs to several tons. The simultaneous occurrence of various
kinds of salt which can react with one another is an additional
negative factor.
The next technological problem was posed by the wali
materiał itself. The parts dating from the end of the 18th
century were made of brick and lime-sand mortar; for the
bartizans specially moulded brick was used that would conform
with the curvature of the face. The wali face in this phase
was covered with a fairly thin coat of lime-sand floated plaster
coloured red. The brick used for 19th centuiy additions to the
wali differed in size from that present in the earlier phase;
the wali was pointed with lime mortar with a brick-powder
filier. In the 20th centuiy the wali was jointed with cement
mortar. This accelerated damage to the brick owing to the
obstruction of evaporation through joints.
Following the analysis, it was accepted that at the present
stage of eonservation theory and practice it would be impossible
to extract soluble salts from the entire wali substance; nor
would it be possible to convert the salts into an insoluble
form on account of the presence of nitrates. Only desalination
in the places of salt concentration was contemplated with a
view to its reduction to average level. It was accepted as a
basie line of counteraction to prevent salt accumulation by
reducing water migration within the wali substance - in the
first place by repairing the leakage, an adeąuate solution for
damp insulation, and application of diy methods of cleaning
the face. The hydrophobisation of the extemal face was con-
sidered too hazardous and not very effectiive. Such a treatment
would be advantageous in respect of the effect of rainwater
on the sloping outer face, but it might lead to salt accumulation
under the hydrophobised layer and in conseąuence to the
flaking of that layer. However, hydrophobisation was accepted
for the inner face and the coping of the parapet, that is, the
places of water penetration.
A slightly different procedurę was chosen for the bartizans.
The character of the objects (moulded brick) reąuired strict
conservation treatment, with as much authentic materiał as
possible preserved. The damaged bricks were not replaced,
instead the losses being replaced with mortar. As the bartizans
are not exposed to the inflow of water from the inside,
desalination and hydrophobisation of the whole surface was
considered advisable.
The reconstruction of floated plaster on the face of 18th
centuiy phase walls presented a specific technological problem.
As the original technology was not durable, it had to be
modified so as to ensure the lasting qualities of the floated
plaster; in other words, reconstruction of its original appearance
using a new technology was assumed. On the basis of inves-
tigations and practical tests the composition of the floated
plaster was established: slaked lime and low-alkaline cement
as joints, brick powder and granular glass-making sand as
fillers, pigments, and a synthetic modifier inereasing adhesion,
plasticity, and frost-resistance (hydrous dispersion of synthetic
resins, non-hydrophobic).
The first stage of work in the years 1993—1994 was carried
out on arms E and F. The experience gained at that stage
served to coiTect the technological assumptions; in 1995 arms
G and H were treated following these directions. Conservation
of the remaining ten arms is planned for the subseąuent years
of the large-scale restoration of Wawel.