11-14 Stone Deterioration Flashcards
11 - Alveolations 12 - Material Perforation 13 - Encrustation 14 - Biological Growth
A single or series of surface punctures, holes or gaps, made by a sharp tool or created by an animal. The size is generally of millimetric to centimetric scale. Perforations are deeper than wide, and penetrate into the body of the stone.
Perforation
Point-like millimetric or sub millimetric shallow cavities. The pits generally have a cylindrical or conical shape and are not interconnected, although transitions patterns to interconnected pits can also be observed.
Pitting
Generally coherent accumulation of materials on the surface.
Crust
may include exogenic deposits in combination with materials derived from the stone.
Crust
Sub-types of Crust
- Black Crust
- Salt Crust
Accumulation of exogenic material of variable thickness. Some examples of deposits : splashes of paint or mortar, sea salt aerosols, atmospheric particles such as soot or dust, remains of conservation materials such as cellulose poultices, blast materials etc.
Deposit
Change of the stone color in one to three of the color parameters : hue, value and chroma.
Discoloration
corresponds to the most prominent characteristic of a color (blue, red, yellow, orange etc.).
hue
corresponds to the darkness (low hues) or lightness (high hues) of a color.
value
corresponds to the purity of a color.
chroma or saturation
Sub-types of discoloration:
- Coloration
- Bleaching
- Moist Area
- Staining
Generally whitish, powdery or whisker-like crystals on the surface. Efflorescence’s are generally poorly cohesive and commonly made of soluble salt crystals.
Efflorescence
Generally whitish, powdery or whisker-like crystals on the surface. Efflorescence’s are generally poorly cohesive and commonly made of soluble salt crystals.
Encrustation
They are generally found below areas of the building where water is percolating or has percolated in the past.
Encrustations
Thin covering or coating layer generally of organic nature, generally homogeneous, follows the stone surface. It may be opaque or translucent.
Film
Aspect of a surface that reflects totally or partially
the light. The surface has a mirror-like appearance.
Glossy Aspect
Engraving, scratching, cutting or application of paint, ink or similar matter on the stone surface.
Graffiti
They are generally the result of an act of vandalism.
Graffiti
Chromatic modification of the material, generally resulting from natural or artificial ageing and not involving in most cases visible surface deterioration.
Patina
Sub-types of Patina:
- Iron rich patina
- oxalate patina
Deposit of a very thin layer of exogenous particles (eg. soot) giving a dirty appearance to the stone surface.
Soiling
With increasing adhesion and cohesion, soiling can transform into a ______
Crust
It may originate from atmospheric pollutants (industrial, domestic or car exhaust products) or from particles transported by running water or heating convection.
Soiling
Poorly adhesive soluble salts, commonly white, located under the stone surface.
Sub florescence
They are hidden, unless the stone layer over them detaches. In that case, salt crystals become visible on the newly exposed surface.
Calorescences
Colonization of the stone by plants and micro-organisms such as bacteria, cyanobacteria, algae, fungi and lichen (symbioses of the latter three).
Biological Colonization
It also includes influences by other organisms such as animals nesting on and in stone.
Biological colonization
They are microscopic vegetal organisms without stem nor leaves which can be seen outdoors and indoors, as powdery or viscous deposits (thickness : tenth of mm to several mm).
Algae
It forms green, red,
brown, or black veil like zones and can be found mainly in situations where the substrate remains moistened for long periods of time.
Algae
Vegetal organism forming rounded millimetric to centimetric crusty or bushy patches, often having a leathery appearance, growing generally on outside parts of a building.
Lichen
They are most commonly grey,
yellow, orange, green or black and show no differentiation into stem, root and leaf.
Lichen
It is composed of a thallus, eventually bearing fruiting bodies, generally developed on the stone surface, and rhizomes that may penetrate deep into the stone (tens to several millimeters).
Lichen
Sub-types of Lichen
Crustose
Folious
Epilithic Types
Vegetal organism forming small, soft and green cushions of centimetric size.
Moss
They look generally like dense micro-leaves (sub- to millimetric size) tightly packed together.
Mosses
They often grow on stone surface open cavities, cracks, and in any place permanently or frequently wet (masonry joints), and usually shady.
Moss
They develop brown rhizines and may create a micro-soil zone between the stone surface and the green part.
Mosses
Microscopic fungus which colonies, to the naked eye, look like a downy film or a network or star-like millimetric patches of filaments of diverse colours (white, grey, black).
Mold
by their filamentous and/or chain-like growth may penetrate several centimeters into the stone substrate.
Molds
Vegetal living being, having, when complete, root, stem, and leaves, though consisting sometimes only of a single leafy expansion (e.g. Tree, fern, herb).
Plant
Formation, on the stone surface, of cavities (alveoles) which may be interconnected and may have variable shapes and sizes (generally centimetric,
sometimes metric).
Alveolization
Loss of original surface, leading to smoothed shapes.
Erosion
Sub-types of Erosion
- Differential Erosion
- Loss of Components
- Loss of matrix
- Rounding
- Roughening
: occurs when erosion does not proceed at the samerate from one area of the stone to the other. As a result, the
stone deteriorates irregularly.
Differential Erosion
Partial or selective elimination of
soft (clay lenticles, nodes of limonite, etc) or compact stone
components (pebbles, fossil fragments, geological concretions,
lava fragments).
Loss of components
Partial or selective elimination of the
stone matrix, resulting in protruding compact stone components.
Loss of matrix
Preferential erosion of originally angular stone
edges leading to a distinctly rounded profile.
Rounding
Selective loss of small particles from an originally smooth stone surface.
Roughening
Loss of stone material clearly due to a mechanical
action.
Mechanical Damage
Sub-types of Mechanical Damage:
- Impact Damage
- Cut
- Scratch
- Abrasion
- Keying
Mechanical damage due to the impact of a projectile (bullet, shrapnel) or of a hard tool.
Impact damage
Loss of material due to the action of an edge tool.
Cut
Manually induced superficial and line-like loss of material due to the action of some pointed object.
Scratch
Erosion due to wearing down or rubbing away
by means of friction, or to the impact of particles.
Abrasion
Impact damage resulting from hitting a surface with a pointed tool, in order to get an irregular surface which will assist the adhesion of an added material, a mortar for instance.
Keying
Network of small interconnected depressions of
millimetric to centrimetric scale, sometimes looking
like hydrographic network.
Microkarst
They are due to a partial and/or selective dissolution of calcareous stone surfaces exposed to water run-off.
Microkarst
Empty space, obviously located in the place of some formerly existing stone part.
Missing part
Sub-type of Missing Part:
Gap
hollow place in the stone surface, hole.
Gap
