Loose surface dirt can generally be safely removed from a gilded surface by carefully brushing with a soft-haired brush. Tate uses goat's hair brushes for this, purchased from a conservation supplier.
Ingrained surface dirt can be considered to detract from a frame's original condition. Tate conservators clean gilded surfaces using a variety of techniques, either dry or with solvent mixtures, depending on the type of gilding scheme and its general condition. Prior to any such treatment the nature of the scheme has to be understood by examination and cleaning tests.
Beyond gently dusting gilded frames, owners should seek the services of a specialist conservator to work on these often fragile surfaces which can be very quickly damaged.
Traditional gold leaf that is laid onto frames is very rarely 100% gold; in fact, to make the gold more malleable during the beating process and to improve strength and handling qualities when it is paper thin, a proportion of up to 50% of pure silver or up to 3% of pure copper is added. The addition of even tiny proportions of silver and copper can dramatically alter the appearance of the gold; silver making it lighter in colour and slightly 'colder', copper making it darker and tending towards a 'warmer' tone. Various effects can be created by using gold of different colours on the same frame.
Frames can also be decorated with metal leaf other than gold; these can be in a combination of various metals, such as copper and zinc, to create an imitation gold leaf, sometimes referred to as Dutch metal or schlagmetal, or single metals, either copper, aluminium or brass. Metal leaf (other than gold) is usually produced in sheets approximately 13 x 13 cm in size, whereas gold is produced in sheets approximately 8 x 8 cm. A worn area of a frame sometimes reveals the overlapping metal leaves and can therefore be useful in identifying the materials used.
In the case of frames that are not decorated with gold, a layer of varnish or lacquer is applied, both to prevent the surface oxidising and to give some physical protection to the surface. This lacquer layer often darkens dramatically over a long period of time. If this layer is accidentally scratched or partially removed, the underlying metal leaf will oxidise very quickly, disfiguring the surface. Real gold is often protected with a thin layer of weak parchment size, or size combined with shellac, known as ormolu. Since the oxidising components of gold leaf alloys are relatively small, this layer usually performs the task of toning down the bright nature of the new gold, and often contains small quantities of ochre or burnt umber pigment dissolved in the ormolu solution for this purpose. Very bright or burnished gold areas of a frame will have little or no additional layers applied; this is to retain the polished appearance, creating contrast with matt areas in a different part of the frame.
Firstly, look at the period/date of the frame, a pre-nineteenth century date may suggest a carved method of ornament, although frames have continued to be carved up to the present day. From the late eighteenth century English Composition started to be used as a quicker and less expensive means of recreating the effect of hand-carved ornament. English Composition (or 'compo' as it is often called) is a putty-like material pressed or rolled from metal and wooden moulds and applied to the surface of the frame for decorative effect. It can then be painted and gilded.
Secondly, look at the surface of the frame. Areas of wear and damage may well reveal the timber substrate very near to the surface, possibly indicating carving. Carved frames are sometimes 'whitened-up' prior to gilding with only a few layers, thus allowing heavy grain and knots to echo through to the gilded surface, which is all part of the frame's integrity.
Thirdly, by the nature of the constituents of composition, cracking occurs, to a greater or lesser degree, throughout the frame's life. If left untreated, the mouldings affected may eventually delaminate from the frame and leave unsightly gaps. Composition is generally a buff-grey colour, but usually was placed on a white layer. As well as composition, we see plaster and various other recipes using a plaster base being used. Plaster is more stable, but is prone to damage through impact, leaving areas which appear white. Frames are sometimes found to be made from papier-mâché, which may be indicated by the presence of fibres in any areas of damage.
Conservators support the Tate's core purpose to care for the National Collection of British, Modern and Contemporary art, and artworks on loan to Tate. In addition to restoring artworks, they examine and document the artist's materials and techniques used to make each work. This may involve detective work to discover old techniques and materials no longer used today. Or it may necessitate research into new materials to assess their possible long term behaviour. Conservators and conservation scientists predict long term change in artworks by recording their condition and logging any subtle shifts in their structure or appearance over time. They assess ways of slowing down the aging process. This includes making recommendations for best practice in the lighting and environmental conditions of display galleries, storage and transportation.
Conservators also track the condition of artworks while on display at Tate and when on loan to other venues. They encourage best practice by researching and specifying low risk methods to handle, pack, store and transport artworks. They search for new ways of preserving art while making it as accessible as possible, and increasing knowledge and understanding of the material history and concepts inherent in an artwork.
For more information on the care of paintings see the ICON (Institute for Conservation) website at http://www.icon.org.uk/.
To store a painting, consider protection from dust, mould, insects and from abrasion or impact. Ideal conditions are those that are stable - neither too dry nor too damp. 50% relative humidity, and 20°C are standard environmental conditions for storage. Exclude light to reduce fading and discolouration. Protect from dust with a suitable covering; this could be tissue paper or polythene. For modern paintings and unframed works, consider providing a carrying frame, or L-section wooden frame, that projects far enough beyond the front of the painting to allow the frame to be wrapped in polythene without touching the paint surface (see packing methods).
Painting Conservators can answer questions or direct you to other sources of advice. See the 'Contact us' section of the website.
Tate's Collection is available for display at all of its four sites, therefore artworks must be
moveable. For paintings, the display frame is the most vulnerable part of the work. It is the
means by which the work is handled and may be exposed to the occasional unintended contact with
objects and surfaces. A simple L-section wooden frame, or 'carrying frame' is often supplied to fit
the painting into for extra protection
Transit Frame
Specification (PDF)
The L-section projects out in front of the painting and its frame.
There is a gap on all four sides so the work can be secured. A carrying frame is especially useful
for works without display frames. It is a simple measure, but a very effective one for reducing
wear and tear. It can also be wrapped in polyethylene sheeting which, when overlapped and taped,
provides a stable atmosphere around the painting for storage. The only risk comes if the painting
itself is in a damp environment. The high moisture content in the framed painting will make the
trapped air humid and in time mould could form. Tate stores its paintings in air conditioned
buildings so this is not a concern.
For national transport Tate uses air-ride suspension temperature-controlled vehicles. Because the temperature in these vehicles is kept similar to that in the museum, the painting in its wrapped carrying frame is considered adequately protected. Blankets are often used to absorb shocks when a painting is put down. Straps are then used to hold the work against the inside of the lorry and to secure any other items in the vehicle.
For international loans requiring transit through an airport, the rigours of cargo handling make the
provision of a packing case with cushioning and a resilient external shell essential. Packing cases
are made by outside firms to Tate specifications. A typical set of packing specifications is provided
as an example here
Specification for a Single Painting (PDF)
Very large paintings may have to be taken off their stretcher and rolled for transportation, but this should always be avoided where possible since removing and re-applying the attachments damages the tacking edge of the canvas. Furthermore, rolling may crack the paint. One absolute rule if rolling is necessary is that the paint surface must be face out or the paint will be creased and compressed, with ultimate adverse effects. A roller with as wide a diameter as possible should be used, with a minimum diameter of 1foot (31cm). If the painting is thickly and recently painted, it is highly likely that it is still wet. This obviously has to be carefully checked for. An interlayer of Glassine paper is a useful safeguard generally. Care should be taken to keep the roll off the ground by putting strips of foam or similar padding around each end, otherwise the weight will cause distortion and possibly cracking. Wrap the rolled up painting with polyethylene sheeting and seal. The painting on its roll should not be stored for long periods; problems may be developing.
It is not unusual for a painting to exhibit cracks. These occur when the stress applied to paint is greater than the force holding the paint film intact. Cracks are caused by stresses inherent within the painting or by external forces. An example of the latter would be if a painting is struck by an object, such as a swinging handbag or rucksack. This sudden force applied to the surface might cause the paint film to deform and crack quickly. Other cracks develop slowly over time, as a result of minute changes due to varying temperature and relative humidity levels. The different materials that make up a painting: the support, size, ground, paint, other media and resin layers all absorb and desorb moisture at different rates. Minute difference in expansion of materials can cause stress fractures that develop and grow more apparent over time.
Inherent stresses within the painting may be caused by the nature of the paint itself. Paint that is brittle is obviously more prone to cracking than paint that is flexible. Paint tends to become more brittle over time so most oil paintings over eighty years old exhibit cracks. There are many factors which influence the brittleness of paint: the type of media, the amount of pigment, whether the paint is thinned on application and how it is applied to the support. Ductile or alligator cracks occur as the paint dries, if the media shrinks and retracts. These distinctive cracks have soft edges and open networks, exposing underlying paint or ground layers.
The best way to reduce the chances of cracks forming is to control the moisture in the air, aiming to keep it stable and at a moderate level, ideally 55%RH. Where possible, extremely stable conditions can be achieved when the painting is sealed by surrounding it with moisture barriers; moisture impermeable backboards and having glazing fitted achieve this. When the painting is sympathetically lit, so that bright lights or windows are not reflected in its surface, low reflecting glass can be almost invisible.
Possibly, possibly not. The spots may come from a variety of causes. Most commonly, they are either from mould growth or from the corrosion of tiny metal particles in the paper. The classic reddish-brown marks known as 'foxing' are generally agreed to be the result of micro organisms in the paper. They can occur even in paper that has been kept in normal room conditions. Often they can be lessened in intensity, but only if the image on the paper is stable enough to allow treatment. Many inks and watercolours are water sensitive, and affected by solvents, so it is advisable to consult a trained conservator for advice.
Paper Conservation is taught as a degree course in many of the developed countries. Britain has courses at Camberwell in London (the University of the Arts, London) and at Newcastle (the University of Northumbria at Newcastle). Information is available on these universities' websites. Evidence of aptitude and interest is needed to get onto the courses, and numbers are limited. Finding the finance is not always easy. Once you are qualified, you will need to apply for internships with museums and private conservators in order to broaden your knowledge. Paper conservators in museums do relatively little interventive practical work these days, and do more preventative and exhibition preparation work. Private paper conservators spend much more of their time doing treatments.
Paper is fragile stuff. It is likely to discolour in bright light. Leave a newspaper out in the sun for a day, and then watch it go yellow over the next week. Good quality paper lasts longer, but still suffers from the same complaint. Water colours are applied in such thin layers that even small changes are very noticeable. Inks, especially the ones in roller ball pens, are light sensitive too. This is why galleries limit the light when displaying works on paper: they are trying to make the art last longer.
ICON, or the Institute for Conservation, http://www.icon.org.uk, is the lead voice for the conservation of cultural heritage in the UK. ICON's membership embraces the wider conservation community, incorporating not only professional conservators in all disciplines, but all others who share a commitment to improving understanding of and access to our cultural heritage.
The best way to find a conservator in the United Kingdom who can advise you on conservation matters is through the Institute for Conservation (ICON - see above). ICON has compiled a list of accredited conservators, the Conservation Register, which is available via: http://www.conservationregister.com/index.asp
ICON also provides a forum for groups based around particular conservation disciplines such as paintings, paper etc. to present and discuss current issues, upcoming events and such like. The conservation science group page is located at: http://www.icon.org.uk/index.php?option=com_content&task=view&id=17.
In addition to ICON, there are several other science-based groups within the profession such as the User's Group for Mass Spectrometry and Chromatography http://www.mascgroup.org/ and the Infrared and Raman Users Group http://www.irug.org/. The American Institute for Conservation of Historic and Artistic Works (AIC) at Stanford also has a science-based group called Research and Technical Studies (RATS) http://aic.stanford.edu/sg/rats/index.html.
