Painting Conservation 1 Midterm

Primum non nocere

First do not create further damage

team of four persons

art historian, scientist, restorer, businessman (manager)

painting lifetime

birth (execution), lifetime(negative, positive), human intervention

patina

combination of all the materials present in the artwork, interaction between them, modified aspect that cannot be cancelled out the painting will not look old anymore ———- “clean the dirt without removing the ancient”

4 main ethic principles

• 2 ancient:

  • Reversible

  • Distinguishable

• 2 modern:

  • Minimum

  • Compatible

reversible

all interventions must be reversible- over time materials could become unsuitable for the artwork or better materials and methods are developed

Distinguishable

Restoration interventions should be seen through close inspection, must remain in the background compared to the original

Minimum

”less is more” —- it is better to stop before you do something that might compromise the artwork in the future —- just stabilize it

compatible

the materials used should work with the type of artwork —- physically, chemically, and aesthetically

Canaletto

believed the restorer should know what the artist did and there intention, read about them and the artist will tell you what they used

dirt

material in the wrong place, should be removed without removing material that is in the right place

dirt can be…

• foreign matter, not part of the original object; physical addition (ex. Dust)

• Product of alteration of the original material of the object; chemical change (ex. Metal corrosion)

natural dirt vs synthetic dirt

• natural dirt- oils fats wax: hydrocarbons due to polluted atmosphere, black smoke, desiccation oils; resins: varnishes, shellac, amber, copal, balsams; proteins: glues, casein, egg; polysaccharides: starch, gum, honey, molasses

• Synthetic dirt- vynilic resins, acrylic resins, ketonic resins

before cleaning ask

• why clean? Is the dirt doing damage?

• Can the object tolerate being cleansed (physically or chemically)?

• What will be the effect of cleaning for the appearance o fate object and for its stability?

• How often will it need to be cleaned in the future?

• How can we clean an object? When do we stop?

Cleaning should be…

• a selective gradual process(act only how much is necessary)

• Controlled with visual or diagnostic exams during the removal (microscope and UV fluorescence)

• The solvent should be east to neutralize and remove

Main cleaning methods

• chemical- (physical) aimed at softening the substance the solvent must be similar to the substance; we must work only on intermolecular forces Solubility Triangle by Teas; use of organic liquid solvents, neutral, very volatile

• Mechanical- dry method, remove by scalpel without softening it; long rime consuming, high ability of the operator; microscope

• Biological enzymes- can be used on dirt of preteen origin, very selective cleaning

• Water based- set up by Richard Wilber’s in 1980s to remove superficial dirt and top skin varnishes; viscous gels (resin soaps or solvent gels)

Cleaning tests- “do it yourself analytical technique”

• in order to identify the pigments and binders and the nature of our dirt

• Fast, inexpensive, fairly reliable

• Useful because done by the restorer himself, with knowledge of art objects

Teas Solubility Triangle

• how does the surface respond to the solvents?

• Keyword= polarity

• Low polarity= 99-98

• High polarity= 35-36

Solubility of materials in the teas triangle

1) wax

2) oils

3) resins

4) aged oils

5) proteins, polysaccharides

The TEAs Triangle can be used to predict the solubility of certain materials by determining their Fd level

Water based solvents

needed when we have to remove not varnishes or retouchings but rather polysaccharides (gums) or proteins (glues)

enzymes

can be used as cleaning tests, in order to determine the dirt “component substance” because enzymes are very selective

an approach to cleaning

chemical analysis → chemical composition of materials → solvent

Solubility test → materials polarity → solvent

cleaning rules

• always under clean rather than over clean

• In Italy you cannot remove the patina only the layer of surface grime and partially the one of the oxidized varnish must be removed

• Water is the most harmful, should never be used unless you have solvents and gels to keep it up from contact with the paint and varnish

• Never use ancient recipes simply because they are found in ancient treaties

what to clean?

Dust, solid particles (candle smoke), pollution

Solvents

the solvent must remain on the surface, it must not penetrate

Why would a solvent penetrate?

• porosity- absorb material on top; would carry down your solvent layer

• Capillarity (phenomenon)- solvent ca be pulled downwards, via the craquelure (fine crevices)

• Volatility- evaporates; opposes porosity and capillarity

• Viscosity- the impossibility to flow, the friction in a liquid, keeps the liquid ages, so it does not flow

what do we clean and how do we start?

three main interventions: consolidation, relining, cleaning

• begin with mild cleaning, then face with a glue (usually rabbit skin), carry out all the support/intervention needed

• Follow with a second level cleaning, cleaning removes surface dirt and removes retouching

• Feather duster for just dirt, painting must be vertical, then dust, and can put a fan parallel to the painting

Varnishing

must wait at least 48hrs before varnishing after cleaning, most varnishes are easily soluble in alcohol diluted with Petroleum (evaporates in 2hrs) or turpentine essence (2 yrs) if you varnish to early your solvents will keep evaporating and the varnish will pre-oxidize or turn matte

Removal of retouchings

• linseed oil has two chemical bonds, one bond is broken after 5 yrs another after 150 yrs

• Chemically there are three main periods, 1 to 5 yrs or 5-150 yrs, then anything beyond 150 yrs

• With petroleum a young retouching comes off (1-5 yrs)

• With DMSO, 5-150 yrs, it penetrates organic tissues

• Over 150 yrs the retouching wont jellify with DMSO — retouching will swell only if it is younger

• Over 150 yrs, use acetone, you can remove the retouching but you risk taking off the original so do so mechanically

Plastering

• Support (missing canvas, missing wood)

• Priming (missing gesso)

• Color (abrasions of thick paint layers)

Missing wood

• structural work; physical issues

• Pegs V shaped

• Araldite/ Vynavil + wood paste

• Balsite

Balsite

accepts gouache or bole but has rough texture, render it smoother with stucco

Missing gesso

rabbit skin glue and gesso (calcium carbonate pigments)

• modostuc (acrylic flue)

• Wax/resin

• Colored stuccos (to avoid gouache undertone layers)

missing color

• Acquapasto W/N

• Mix pigments and gesso

sanding plaster down

• by scalpel

• By abrasive paper

surface texturing

• Negative- recreating the cracks on the painting

• Positive- recreating the brushstrokes, high points on a painting

wood panel paintings: historical evolution

1) Byzantine period (6th -13th century)

2) Transition period (13th-14th century)

3) Renaissance period (14th-16th century)

Byzantine period

• 6th-13th century

• Religious expression

• Uniform and anonymous

• Defined rules to represent figures

• Most widely used painting technique was tempera

  • Water based, emulsion-type, and oil- based binders

Transition period

• 13th -14th century

• New artistic expression began

• Panel painting became more diffused

• Artists began to sign their works

• Representation of God and nature became more realistic

• Bigger formats and dimensions

• Execution technique and materials are similar to previous period

Renaissance period

• 14th- 16th century

• Golden age of wooden panel paintings

• Transition from tempera to oil

• Oil painting → increased fluidity. Easiness blending colors, more 3-D figures, glazes, glossier appearance, artist has more freedom

• All over Europe becomes more refined, materials are selected following a quality control process

decline and shift to canvas

weight and portability, size and scale, flexibility and durability, cost and availability, cultural shift

Pliny’s Treaty

• panel paintings in disuse because mural paintings were preferred

• Only Roman patricians commissioned portrait panel painting due to their status

• Two techniques used: tempera, encaustic (heated mixture of pigments, molten wax and resin)

Heraclius’ Treaty

• three books, first two 10th century, Italian origin, third book13th century, French origin

• Little is known about the author and where or when the recipes were made

• Tips on wooden support

Theophilus’ Treaty

• one of the most complete medieval technical texts and an essential historical reference

• Three books: painting, glassmaking, metalworking

• On panel painting, info on how to glue wooden boards together with casein + lime, stability

Cennino Cennini’s Treaty

• extensive collection of the best techniques and recipes for creating lasting artwork

• Includes detailed descriptions about many techniques and materials

• Revolutionized the way artistic techniques were explained

• Importance info on the lives of the artists of the time

• Dignity of Art

• Clear distinction between drawing and color, the two fundamental pillars of art

• Demonstrates precision in terminology and a vast knowledge of materials

• A devout admired of Giotto and glorifies his style and technique throughout the whole treaty

• Denning prizes the longevity and pure aesthetics in artworks following Giotto’s teachings

• Experience in the bottegga, pupil of Agnolo Gaddi → son of Taddeo Gaddi → Giotto’s pupil

antependium

altar frontals (11th-12th century)

inconstasis

a screen which serves as a stable support for icons and separates the nerve from the altar, culminated with a crucifix positioned over the worshippers leaning slightly forward, eliminated in 16th century after the counter reformation

Crucifixes

12th-13th century in Italy, hung above the altar, denoted great complexity in their construction

Dossale/reredos

13th century onwards, moveable panels placed on top of hte altar during mass

• up until the 17th century the priest would stand in front of the altar (ad orientem)

altarpieces

reredos became more elaborate, began being called altarpieces, religious subject matter above and behind the altar (painting, fresco, relief, sculpture) influenced by Byzantine art

Types of altarpieces

• predella- row of smaller scenes under main panel

• Diptych- two panels

• Triptych- three panels

• Polyptych- four or more panels

• Winged- moveable wings, can be opened or closed

other shapes

• tondo- circular painting

• Pala Quadra- one central compartment enclosed by architectural backgrounds and landscapes

type of wood

poplar, most popular in Italy due to its availability, cheapness, stability, lightness, easy to dry and process ; drawbacks, low natural durability against fungi and wood-boring insects

crossbeams

harder species like chestnut or olive tree used, but poplar was used from the 16th century

type of cut

radial and tangential

• radial- widest board that can be obtained from a given log, less prone to cupping, contains logs pith (low strength, prone to cracks), produces lots of waste

seasoning

good natural seasoning practice may require years for boards to reach satisfactory absence of moisture gradients and settling of internal stresses (Cennini stances minimum 50 years) specific number varies between species

Joining boards

Usually glued with animal glue or casein, square edged before gluing, done quickly and precisely, wood splines or dowels were used

Cesare Brandi

• restorer, historian, and scholar of Italian art

• His theory of restoration was combining the historical value and the aesthetic value of

• Aim to re-establish the potential oneness of the the work of art, without erasing every trace of the passage through time of the work of art (patina)

• Dual aesthetic and historical nature, in view of its transmission to the future

• Restoration is a critical act to recover the artwork wit producing a historic forgery, but without limiting it to mere conservation

Color Retouching Phases

1) surface texturing

• negative texturing: by impression or incision

• Positive texturing: by applying diluted filler with a brush to imitate the brushstrokes

2) watercolor/gouache base color layer

• paler and cooler tonalities than original

3) varnish color glazes

• a layer of varnish is applied before the final color retouching on top of the watercolor/gouache base

• After the varnish color is applied a final spray varnish layer is applied

neutral

When a damaged area or lacuna is too big to be redone, due to its importance, the lacuna is covered with a neutral color making it the background drawing attention to the original

Chromatic abstraction

chromatic in painting of the lacuna, by applying pure-colored dashes (tratteggio) in layers by cross hatching

Chromatic selection

Chromatic and formal in painting of the lacuna with the rest of the inpainting, application of pure colored dashes in layers

Pointillism

the color is recreated, not necessarily the shape, using dots

Undertone/sottotono

imitative pictoral reintegration intervention aimed at reconstructing a chromatic and formal connection of the lacuna with the rest of the painting, but using lighter shades (undertone) so restoration is distinguishable

Imitative or mimetic

reintegration technique, does not allow to distinguish restored parts form original