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Pedestal in the Stile of Neo Rococo, Beginning of 19th Century

Introduction

Dimensions:

126cm in height, 34cm in width by 34cm in length (dimensions of footing panel)
Final facing:
Parcel water silvered, parcel water gilded, parcel imitation of gilding and parcel painted
Type of treatment:
Restoration
Storage and display:
Private collection, for everyday use

Condition

Pedestal was brought in studio with traces of previous interventions. It was probably cleaned with some very aggressive substance.
Gesso was seriously damaged probably during the cleaning process. Most of thinner gesso was removed. Peaces of ornament gesso were missing. Part of footing panel and bottom ornament was carbonized.
Wooden structure was cracked but in constructional sense firm.
Peaces of gold leaf imitation were found in the corners of ornaments. Silver was found on the leg ornaments but only in traces. Gold was found on the other ornaments and on the borders of top and footing panel in traces too.
Traces of dark green color were marked on the area of naked wood. Paint probable penetrated through gesso and colored wood. (fig.1., fig.2.)

Technical Analysis

Prior to restoration work the following analysis were performed:

Analysis of Materials and Techniques Involved

The body of the object was made of Beechwood (Fagus sp.). Ornaments were made by carving and engraving. Carved ornaments were covered with approximately 3 mm thick layer of traditional gesso (calcium carbonate powder and organic adhesive probable Fish-eye glue) and with layer of dark red bole. Other surfaces including engraved ornaments were cowered with thinner layer of traditional gesso. Ornaments were parcel water gilded and silvered. Background of floral ornament in the middle of object was decorated with imitation of gilding. Other surfaces were painted.
Samples for pigment test was taken from colored area of wood and analyzed.

Analysis of Substance Used for Cleaning

Samples were taken from gesso and wood area of object and analyzed due to suspicion that some amount of substance used for cleaning, still, was present in wood and gesso.

fig.1. click on to zoom fig.2. click on to zoom
Choice of Treatment

Treatment on this object was performed in two phases:

Phase I: Neutralization of Substance Used for Cleaning

Results received from Laboratory for Research of Materials indicated on presence of soda (NaOH) in booth samples. To remove it in order to prevent from very possible reaction with materials that will be in use in restoration process, object was rinsed with 50% ethil alcohol followed by rinsing with nitro thinner (7).

Phase II: Choice of Restoration Treatments

Selection of the Materials and Procedures for Crack Recovering

For recovery of cracks in wooden body test was made with admixture of powdered gypsum (CaSo4), Kaolin and PVAC resin. Prior to application of admixture crack was moistened with 15% ethyl alcohol to assure good contact of admixture and wood. Solidification time was about 15 minutes. Sample was left to dray for 12 hours. Test resulted with solid, consolidation backfill.

Selection of the Materials and Procedures for Consolidation and Recovering of Original Gesso

Due to good experience with admixture tested on cracks, it was tested for filling of areas of ornament where the parts of original gesso missed. Area was prepared with 15% ethyl alcohol as the crack in previous test. Admixture was pushed into and flattened with moistened spatula. The Result was satisfactory.
In order to consolidate the small cracks in original gesso, make better contact within original gesso and new fill and make solid ground for new gesso the 'contact ground' was tested. Request was to obtain surface solid enough to resist pressure during the polishing of gold and silver and porous to except new gesso. The ground was composed of calcium carbonate, in form of fine powder (Bologna chock), zinc oxide powder and PVAC resin. By the and of mixing 90% Izo propil alcohol was added to improve leaving of captured air. To make it applicable with brush admixture was diluted with distilled water. Surface was coated 3 times with time delay of 15 minutes to provide solidification time for each layer. Sample was left to dray for 12 hours. The result was solid but porous surface, resistant enough on pressure preventing the original gesso from delaminating.

Selection of the Pigments and Ground for Pigment

Pigment test result helped in determination of color and adoption of hue. Due to previous good experience with Oil type (1) pigment, It was decided, to use it in this occasion too. Pigment was mixed with prefabricated oil color medium (2) offered by same manufacturer.
To make a ground for mixed oil color it was thought that it would be much better to use prefabricated ground for oil colors applicable on wood instead of any kind of gesso made of calcium carbonate, filer and organic or inorganic resin. Test was made with prefabricated UB ground (3) applied in two layers. Property of this ground is to seal pores of wood with very thin layer on it. Test result was very good. Oil color distributed successfully and did not penetrate, after drying layer was even in shine and hue.
After analyzing quite similar objects made in same period (middle of 19th century) and in same stile (neo Rococo) it was decided to make light France polish on colored segment in order to achieve shine, deep look. Test was made with bleached shellac (4) to avoid deformation of color hue and result was good.

Selection of the Type and Hue of Gold Leafs and Material for Imitation of Gilding

In order to achieve deeper, sad look of water gilded ornaments 24 karat 3 layer gold leafs were selected. To contribute to this look, dark red bole was selected. For finishing background of floral ornaments in the middle of object schlag metal was selected, with corresponding hue to hue of gold leafs.
To emphasize engraved floral ornament in the middle of object and net looking ornament in the middle of appears part of object, but to make corresponding hue with surrounding green color Mica powder mixed with small amount of green neutral pigment (5) was selected.

Restoration Process

Tested admixture was applied on cracks and flattened by moistened spatula. Prior to application cracks was moistened with 15% solution of etil alcohol. Delaminated peaces of ornaments gesso were removed mechanically. Previously tested Procedure was applied now. After 12 ours of drying areas of intervention were shaped by the help of turbine.
Prior to application of the 'contact ground' surface of ornaments was cleaned whit 96% ethyl alcohol. The 'contact ground' was applied in three layers as it was tested and then left to dray for 2 hours. New traditional gesso made of technical whiting (CaCo3), zinc whiting (ZnO2) and rabbit skin glue was applied shortly afterwards in four layers. Every layer was left to solidificate for 15 minutes.
After 12 ours surfaces of ornaments was shaped with sandpaper. In order to prepare flat and smooth surface important for quality of water gilding sanded surface was colored with ocher bole and sanded again with 4 grades of sandpaper. During the sending surface was rinsed with mineral spirit. Next 12 ours object was left to dray (fig.3.).

fig.3. click on to zoom
Bole (6) mixed with 5% rabbit skin glue was partially applied in 6 layers and then ornaments were gilding and silvering by water gilding technique. After 12 our gilded surfaces were burnished.
On the surfaces planed for imitation of gilding, prefabricated nitro ground (7) were applied in 3 layers. After 30 minutes of drying one coat of synthetic oil size (8) colored with dark red neutral pigment (9) was applied. Imitation was finished with chosen material.
From the parts of object planed for coloring remains of original gesso were removed mechanically. Ground pigment and mixed oil color was applied.
After 24 ours Traditional French Polish technique was performed with tested schelac.
Mica powder mixed with neutral pigment and Pigment adhesive was applied on engraved areas before French polish. Object was left to dray for 24 ours and then Toning was carried out with 'bitumen from Judea' (10) mixed with Turpentine and Damar lacquer. Toning procedure was performed on all surfaces. On colored surfaces marble look was achieved with toning procedure (fig.4.). Next 12 ours object was left to dray and then traditional Franch polish was performed again.
To prevent from possible damages ornaments were protected with Zapon lacquer (11) thinned with acetone (propanone). (fig.5.)
fig.4. click on to zoom
fig.5. click on to zoom
List Of Used Prefabricated Materials

1. Oil pigment: Lukas GmbH, Germany
2. Medium: Lukas GmbH, Germany
3. UB Ground: Duga, Yugoslavia
4. Bleached Shellac: Lefranc & Bourgeois, France
5. Green neutral pigment: Lefranc & Bourgeois, France
6. Bole: Red, Lefranc & Bourgeois, France
7. Nitro ground: Duga, Yugoslavia
8. Synthetic oil size: Goldanlegeol - Mixtion, Lukas, Germany
9. Dark red neutral pigment: Lefranc & Bourgeois, France
10. Bitumen From Judeja: Liberon, France
11. Zapon lacquer: Liberon, France

Applied Gold, Silver and Metal Leafs and Powders

Gold leafs: 3-fach stark, 24 Karat, Noris, Germany
Schlag metal: Noris, Germany
Mica powder: Noris, Germany