23.03.2013 Views

Series editors' preface - Wood Tools

Series editors' preface - Wood Tools

Series editors' preface - Wood Tools

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Wax has been used many times to infill loss<br />

in japanning. Unfortunately, once it has been<br />

used it is very difficult to remove. For this reason<br />

wax is not recommended for fills to japanning.<br />

However, wax fills have been used quite<br />

successfully for raised areas where the wax is<br />

prevented from entering the substrate. John<br />

Hill describes the use of microcrystalline wax,<br />

rottenstone and pigment mixed together to<br />

replace missing raised areas on the Pimm<br />

Highboy (Hill, 1976). Beeswax, carnauba or<br />

microcrystalline wax formulations could be<br />

used for fills that only involve the surface layer.<br />

Fills for papier mâché<br />

Paraloid B72 mixed with black pigment and<br />

glass microballoons works quite well to fill<br />

small losses around mother-of-pearl on papier<br />

mâché. It is applied as a bulked paint to the<br />

small areas. It is also useful for small cracks.<br />

The baked paper substrate of papier mâché<br />

is best filled with similar materials. Heavy rigid<br />

materials such as plaster and wood filler<br />

should be avoided. Fills can be made by building<br />

up layers of paper adhered with 3% methyl<br />

cellulose or wheat starch paste. Huxtable and<br />

Webber (1986) give comprehensive directions<br />

for preparing wheat starch paste. Long fibre<br />

paper, such as Japanese paper, is the best<br />

choice for such fills.<br />

Paper fills can also be made in the original<br />

fashion. A mould can be taken of the desired<br />

shape from similar area of the piece, then<br />

paper and wheat starch can be used to build<br />

up the layers within the mould. Leaving the<br />

paper in the mould, it should be baked at<br />

100 °F until the paper is hard. The resulting fill<br />

can be carved to fit precisely then be glued<br />

into place (Van der Reyden and Williams,<br />

1986).<br />

Fills for japanned layers<br />

Paraloid B67 or B72 can be mixed with dye to<br />

achieve a good approximation of the aged varnishes<br />

for both resin and oleo-resinous japanning.<br />

Orasol dyes (Ciba–Geigy) are particularly<br />

useful for this purpose. These dyed resins can<br />

be applied in layers over fills made of paper,<br />

traditional gesso, acrylic gesso, or PVAL and<br />

whiting. Either synthetic resin can be used, but<br />

the gloss of Paraloid B67 is more similar to the<br />

original japanned surface. The potential<br />

crosslinking of B67 should not present a sig-<br />

Conserving other materials II 759<br />

nificant problem if retouch materials are<br />

applied over a reversible isolating layer (see<br />

section 12.3.2). The addition of microcrystalline<br />

wax will give a sheen similar to the japanned<br />

surface (Park, 1994).<br />

Acrylic paints are suitable for inpainting<br />

japanning on papier mâché or metal. The<br />

opaque quality of the paint is not readily<br />

apparent on these materials. The gloss can be<br />

matched to the surrounding areas by building<br />

up thin applications. Acrylic gloss medium<br />

used with mica based pigment works well to<br />

inpaint losses in deteriorated gilded decoration.<br />

Dry pigment can also be mixed with Paraloid<br />

B72, B67 or PVA AYAF and used in a traditional<br />

inpainting approach.<br />

Oil paints have often been used in the past<br />

to imitate the decorative layer. Their use is not<br />

recommended because paint based on drying<br />

oil crosslinks. This will present a serious problem<br />

for future removal from a spirit varnished<br />

surface.<br />

16.7.7 Varnishes<br />

Overall varnishing of japanned pieces will help<br />

to integrate fills and give a uniform appearance.<br />

However this should only be carried out<br />

if the application and future removal will not<br />

affect the original layers of japanning.<br />

Satisfactory, but not always invisible, fills can<br />

be achieved without revarnishing the entire<br />

piece.<br />

High molecular weight synthetic varnishes,<br />

such as Paraloid B72, do not have the same<br />

appearance as natural resins (see section 12.4).<br />

Many pieces coated with high molecular weight<br />

synthetic resins in the past have an unnatural<br />

‘plastic’ appearance, although this problem can<br />

be minimized if thin coats are used. The development<br />

of stabilized low molecular weight synthetic<br />

resins is of particular importance for the<br />

conservation of japanned surfaces. These<br />

resins, discussed in detail in section 12.4.7,<br />

share the optical properties of traditional natural<br />

resins but remain soluble in hydrocarbon<br />

solvents. Stabilized dammar or MS2A can also<br />

be used as a protective coating. Although many<br />

of these resins are softer than the original surface,<br />

they can be formulated or applied so that<br />

they approximate the sheen of an aged<br />

japanned finish. It may be possible to use a<br />

matting agent, spray technique or a mild abra-

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!