Fig (2-4) Classification of weathering forms.
Damage categories are based on the intensity of the weathering forms, Six damage categories have been identified as shown in the next figures.
Fig (2-5) diagram of definitions of damage categories.
Fig (2-6)Map of damage categories with rating of urgency of preservation measures, ”St. Lambertus Church, Monschau- Kalterherberg, Germany” SW tower and part of west facade.
Damage categories and especially damage indices represent very practical tools for reliable
1 Photos of Weathering forms on stone buildings are included in Appendix (A) at the end of the Report.
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judgement/certification of preservation measures, Damage categories locate those parts of a building which intervention has to focus on, Damage indices point out need and urgency of intervention.
2-1-4- Therapeutical steps:
Based on anamnesis and diagnosis, effective and economic therapeutical steps can be proposed and calculated, Important therapeutical and preventive preservation measures are the following:
A) Preconsolidation. B) cleaning. C) sealing – plastering.
D) consolidation. E) protection.
2-1-4-1- Preconsolidation:
Complex and difficult operation required when the degradation process is strong, and obstacles the normal cleaning operations. And It consist in sticking small portions, with minimum amount of consolidator and utilizing reversible materials like Japanese paper, gauze, acrylic resins and other materials that can be removed after the cleaning.
Fig (2-7) photos of Preconsolidation presses: sticking of Japanese paper and adding consolidator.
Fig (2-8) photo of vegetable disinfestations.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
Then must be completely vegetable disinfestations by injection with some chemicals for the superior plants, and by aerosol or brush for the mask or alga. Before starting the disinfestations, the surface must be cleaned with a wooden or plastic palette, then many cycles of product must be done till all the vegetables organism are dead, then removed with brush and water.
2-1-4-2- cleaning:
The aim of the cleaning is to remove any thing that may damage the stone such as Soluble salts, Crust, vegetation and Etc. Cleaning must be controllable by the operator, selective and gradual, non corrosive, and doesn’t leave harmful materials or create breaks. And the main cleaning methods are:
• Nebulized and atomized water. • Water compress with absorbing materials.
• Mechanic method. • Ultrasonic. • Laser.
atomized water: It cleans and remove the encrustations with effect of a washing of water mixed with air that produce an aerosol effect. It needs to have low pressure and the nozzle must not be direct to the surface but must have an angle between 30° to 45°.
Nebulized water: Like atomized water, but without mixing air and water. It is used at low pressure ( max 2 par.). The nozzle are directed to the surface, and it’s effect is direct and
stronger than atomized water
To clean deep crust it needs many cycles of washing, each cycle has a duration of about 10 minutes followed by one hour of drying. After each cycle a sample of the waste water must be taken and continue until the quantity of salt is at demonized water level.
Fig (2-9) photos of cleaning with nebulized and atomized water.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
Absorbing materials: it absorbs all the soluble salts and alternation products and removes different types of spots, and it may be made by (Paper Pulp) or (Absorbing Clay).
Fig (2-10) photos of cleaning with absorbing materials.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
Mechanic cleaning: it is used to remove very consistent crusts that can’t be soluble in water or chemically, using micro instruments as Scalpel , Micro drills, Micro sand blast or Ultrasonic instruments.
Fig (2-11) photos of cleaning with mechanic method and micro sand blasting.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
Laser cleaning: it is anew method of cleaning, and is very good to remove black spots, and it operates only on the external surface by a laser light without any contact but it very slaw and expensive.
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Fig (2-12) photos of cleaning with laser.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
2-1-4-3- sealing – plastering:
This process consists of the removal of old sealing and wrong intervention with mechanical methods, then plastering of cracks or joints with mortar made by the same material of the original stones (smashing the stones at the right grins and may be added some acrylic to make the mortar stronger as possible.
Fig (2-13) photos of sealing process with stone mortar.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
Sometimes it necessary to make integrations of small elements that are broken or lost with material such as acrylic resin, quick lime or smashed stones. For the biggest elements it is fixed with titanium, Teflon or stainless steel bars.
Fig (2-14) photos of integrations of small elements that are broken or lost.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
2-1-4-4- consolidation:
This process aims to give back the continuity to the fragile materials and separated parts by applying an appropriate product with a strong adhesive power, that process improve the properties of the material and make it more resistance to water and humidity.
Fig (2-15) photos of consolidation of fragile materials and separated parts.
Source: (lecture by Prof. D. Villari, Kore university of Enna, Italy).
2-1-4-5- protection:
It is the final operation that aims to slow down the deterioration process and maintain the restoration, It is applicable with brush or spray.
Notes:
1. B. Fitzner and K. Heinrichs, ”Damage diagnosis on stone monuments – weathering forms, damage categories and damage indices”, Working group “Natural stones and weathering“,Geological Institute, Aachen University of Technology, Germany.
2. B. Fitzner, K. Heinrichs, D. La Bouchardiere, ” Damage index for stone monuments”, 5th International Symposium on the Conservation of Monuments in the Mediterranean Basin, Sevilla, Spain, 5-8 April 2000.
3. Barry A.Richardson, "Defects and Deterioration in Buildings", 2nd edition, SPON PRESS, London.2001.
4. B. Fitzner, "Documentation and evaluation of stone damage on monuments", 10th international congress on deterioration and conservation of stone, Stockholm.2004.
5. B. Fitzner, Working group "NATURAL STONES AND WEATHERING", Geological Institute, RWTH Aachen University , http://www.stone.rwth-aachen.de at 1-2009.
6. Villari, D. “Lectures of restoration” Kore university of Enna, Italy, 2008.
7. http://www.irb.hr/korisnici/obelic/euro-med/CA.htm at 5-2009.