University of Malta

Practical and Laboratory Work (2008)
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Stone Cleaning Practical Session

A stone cleaning practical session was held on 23 May 2008 at a chapel in Zebbug, Malta. The various cleaning methods used locally were discussed and tried in situ. These included dry and wet brushing, the use of surgical blades, employing poultices for desalination and for the cleaning of soiling. This exercise was carried out under the expert supervision of Architect Mark Azzopardi, one of the lecturers on the course.

A ”mastru” showed the students the different tools which should be employed in association with cleaning techniques, as well as how these are used.  The students then cleaned a small area of masonry by applying a poultice, followed by brushing and the use of surgical blades.


Wet brushing as part of the practical exercise


Applying a poultice to remove soiling


Cleaning with a scalpel blade after removal of the poultice


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Practical Session on Salt Analysis

On the 26th June 2008, the six postgraduate students following the course on Conservation Technology for Masonry Buildings carried out a practical session on salt analysis in the laboratories of Heritage Malta Conservation Division at Bighi. The session was conducted by Prof. JoAnn Cassar, with the support of Mr Daniel Vella and Mr Laurence Spiteri of the Diagnostic Science Laboratories of Heritage Malta.
The aim of the exercise was to show the students, who are also practicing architects, that simple and cheap tests can be carried out to solve particular problems associated with the deterioration of building materials, thus providing answers which can help in the decision on which conservation methods to use.
Samples of stone and mortar had previously been taken from a historic building in Valletta which exhibited signs of soiling and deterioration. The students were asked to determine whether soluble salts were a possible cause of the deterioration seen both on the façade and in the courtyard. Thus, qualitative analyses for chlorides, sulphates and nitrates were conducted on previously extracted soluble salts.
In addition, simple acid tests, followed by optical microscopy, were carried out to determine whether mortar samples were lime-based or cement based.


Comparing results for qualitative analysis on different samples


Using optical microscopy to examine the insoluble residue


Discussing some of the results obtained


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Practical on Mortar Mixes

On 9th May 2008, the six students following the course leading to a Degree of Master of Science (M.Sc.) / Postgraduate Diploma in Conservation Technology for Masonry Buildings participated in a practical session which allowed them to try their hands at preparing various conservation mortar mixes. This exercise, which was carried out at Heritage Malta Conservation Division, Bighi,  was carried out under the expert supervision of Architect Ivana Farrugia, one of the lecturers on the course, who was ably aided by Conservator Frank Chetcuti.

A number of mixes were first prepared on site. This allowed the students to get the feel of actually making mixes and to note the problems associated with the making of such mixes. Mixes were made using hydraulic lime and slaked lime as binders, whereas the filler was varied to include graded stone dust, pozzolana, marble dust and powdered terracotta. Mix proportions varied between 1:2.5 and 1:3. The beneficial effect of curing during setting was also examined.
The students then tried their hands at pointing a deteriorating limestone wall at Bighi. This was pointed using the various mixes. Besides evaluating the immediate and short term effects associated with use of these various mixes, the students will also be able to monitor the wall to evaluate long-term results.


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Next Courses

The following courses are due to open in October 2018:

M.Sc. in Conservation of Decorative Architectural Surfaces 

(Preparatory Programme).

Last Updated: 8 April 2011

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