Conservation of decorative plasterwork an Irish viewpoint
David McClean describes the elaborate and sometimes flamboyant use of decoration on walls and ceilings
20 Dominick Street - Typical Rococo bird as popularised by Robert West, after cleaning and prior to repairs to the beak.
Virtually all of Ireland's decorative plasterwork dates from after 1700, 16th and 17th century work survives in only a few isolated locations. Dublin has always been renowned for its elaborate and sometimes flamboyant use of decoration on walls and ceilings. Several distinct evolutionary styles beginning in the early 1700s can be identified. Early plasterwork began as a formal architectural treatment of wall and ceilings coinciding with Palladianism and a belief in no unnecessary adornment. Detailing was usually restrained and confined to using elements from the classical orders, where ceilings were divided into heavy compartments of coffers, circles, ovals, squares and rectangles.

This was superseded in the 1730s by the appearance of a late Baroque style which saw the introduction of full figurative work where ceilings were embellished with large scale stylised figures modelled in-situ. The great exponents of this style were the Lafranchini brothers from Ticino and later in the 1750s Bartholomew Cramillion. Designs for ceiling were often based upon engravings of allegorical and mythical subjects from the classical world, while taking into account the shape, size and proportion of the room. Decoration had a vertical and three dimensional effect, with a highly illusionistic emphasis in the extension of space and depth in which the spectator was willingly involved in this artistic illusion as if it were real, but without really being deceived. Typical of this is the great figurative work at Carton House by the Lafranchini brothers, where the elements relate to each other in a most theatrical way.

20 Dominick Street - Ceiling after repainting using Classidur.
By the 1750s, figurative work was being replaced with a lighter and more playful Rococo style. This became particularly widespread in Ireland and Dublin can be regarded as a great centre for it. Robert West who was either a stuccodore or a speculative builder was one of the chief arbitrators of this style in Dublin. Decoration was strung across the ceiling with an emphasis on the asymmetrical and picturesque while using acanthus leaves, festoons, swags and baskets of fruit and flowers with the occasional zoomorphic touch of birds and dragons, which became extremely popular in the 1760s. 20 Dominick Street as built by Robert West in 1755 contains some of the most elaborate Rococo work in the British Isles with some of the plaster birds extended some 16 inches from the wall.

These flights of fancy soon came to an end with the arrival of the neoclassical style of the 1770s where the inspiration came from the archaeological discoveries of Pompei and Herculaneum, transmuted most notably through the works of Robert Adam and in Ireland by Charles Thorpe and Michael Stapleton. Typical was the use of restrained details in low profile, all delicately executed such as ums, corn husks, griffens, sphinxes, ram's heads and trailing wreathes. Much of this decoration still tended to be in free-hand as can be seen in the illustration of 12 Hume Street, with moulds only being used for the most repetitive elements.

The early 19th century saw the appearance of the Greek Revival with its coarser and more ponderous details, usually being confined to heavily enriched cornices and staid centrepieces. The lavish and sumptuous interior of Ballyfin in County Laois by the Morrisons (c. 1820) is an excellent example of Irish Regency decoration at its best. The 19th century also saw the beginning of the revivalist styles of gothic, Tudor, neobaroque and neoclassical. As the century progressed, plasterwork became more elaborate and eclectic, sometimes combining one or more styles but with a loss of the refinement found in the previous century.

12 Hume Street - Neo-classical frieze/cornice circa 1780 by Charles Thorpe before paint removal.
Inadequate protection
Even though it is recognised that Ireland contains a considerable wealth of decorative plasterwork, much has been destroyed as a result of ineffective protection of buildings and more recently because of inappropriate repair works.

Since the 1962 Planing Act, local authorities have been able to list buildings (and from 1976 interiors); however this legislation has been hopelessly in~ adequate as there has been little enforce~ ment and no grant aid available to owners. Protection of historic buildings was not a mandatory function of local authorities and tended to be haphazard. One notable problem was that interiors were listed separately and not automatic cally when a building was first listed. This allowed supposedly protected buildings to have their interiors substantially remodelled or gutted. As a result of this anomaly much important plasterwork has been destroyed. Another problem was that owners were never required to maintain their buildings, consequently many were lost through wanton neglect and sometimes an ensuing dangerous building order, much to the glee of some property owners.

A recent case is 16 Parnell Square, dating from the 1760s and listed by Dublin Corporation. The listing extended only to the exterior even though it had good rococo ceilings in at least three rooms. In 1997 an annexe to the rear was demolished following a fire. At the same time, the owner, a noted property developer in Dublin, decided to take the roof off thus exposing the interior to the elements but while a tenant still occupying the ground floor of the house. An order to make good this damage was made by Dublin Corporation but was largely ignored. The nail in the coffin was the subsequent dangerous building order which resulted in the top two floors being demolished as far as first floor level. This is a typical and ironic situation where a local authority lists a building for protection yet ends up providing the vehicle for its destruction.

Deficient techniques
Much decorative plasterwork continues to be destroyed through the combination of ignorance, lack of education and technical skills. Even where a person is prepared to 'restore' an old house, appropriately skilled and qualified professionals and craftsmen are rarely used. Very often there tends to be a standardised treatment of a building irrespective of its artistic or historical merits, age and condition of its structure. Plasterwork, needing only minimum conservation work is often ripped out and with little regard for its artistic merits and replaced with cast elements which are often off the peg, with no attempt to understand the subtle changes in styles.

A major problem in Ireland is the widespread lack of advise, information and expert craftsmen. There is at present no government body or agency concemed with the establishment of a school of decorative plasterwork, which could oversee the training and education of potential restorers. Such a school is vital and should deal with the aesthetic and artistic merits of plasterwork, the philosophy and ethos of conservation as well as the development of technical and practical skills. Presently it is up to an individual restorer to develop his or her skills through private research and trial and error. Until relatively recently, apprentice plasterers were trained in the traditional methods of running cornices in situ, the casting of elements, and lath and plaster ceilings and studding.

However, the future is beginning to look brighter with the newly passed conservation legislation, which will come into effect in January 2000. This seemingly progressive legislation which will make listing a mandatory function of all local authorities, will see the appointment of local authority conservation officers and place a duty of care upon owners and occupiers of 'protected structures'. Most importantly will provide for the first time, a system of grant aid to be administered by local authorities, but this legislation needs to be tied in with encouraging widespread training and education.

12 Hume Street - Frieze/cornice after cleaning with a solvent based Methyline Chloride
Care and conservation
To begin to restore decorative plasterwork, it would be helpful and important to understand the different methodologies that were employed to apply details to walls and ceilings.

Simple continuous lengths of plain face mouldings such as cornices and panel moulds were originally run in situ using a template in the shape of the desired profile. Larger details were built out using a coarser mix of lime, sand and hair and run across wooden fixings of brackets and laths.

All of the baroque, rococo and much of the neo-classical plasterwork executed throughout the 18th and early 19th century were exclusively modelled or sculpted in situ using fingers and small tools while following the line of a previously sketched drawing or cartoon of the decoration. This usually involved the use of the oldest and finest quality lime putty gauged with sand and sometimes a little gypsum to prevent shrinkage. For really high relief decoration such as rococo birds, it was necessary to build out the work around an armature of wire, wood or nails.

The use of moulds for certain elements became common from the late 18th century. As these moulds were hard, it was only possible to produce casts in short lengths and in low relief. When high relief was required, it was necessary to use a piece mould where the decorative elements were cast separately and pieced together afterwards. it was only during the mid 19th century that the use of soft gelatine moulds allowed elaborate high relief work to be cast in one piece.

Much of the decorative plasterwork produced today is by mass production of cast standardised details. These elements, often crude in design and of poor quality are never appropriate for use in a historic setting. Nevertheless, fine plasterwork in good condition continues to be destroyed and replaced with modern casts throughout Ireland.

Restoration and conservation are two words much abused today without a realisation of what they really mean or entail. To restore means to return an element or detail back to its original form and appearance - it can also mean to use surviving portions to faithfully reproduce exact copies of details that are missing or destroyed. To conserve is similar but with the philosophy of minimal intervention necessary to maintain the original fabric and to promote its long term survival.

One can encounter many problems associated with decorative plasterwork from different periods. What ultimately effects its condition and state of preservation will depend on its age, history, maintenance and the various uses the building has gone through. Firstly, it will be necessary to undertake a survey of the ceiling/comice to evaluate and determine its condition and to devise appropriate methodologies.

Paint removal
The build up of excessive coats of paint on plaster and the consequent obscuring of. detail is a widespread problem. The types of paint used can vary from oilbound distemper and size-bound distemper to modem oils and emulsions. Very often a number of different paint types will be found on a plaster sample. If detail is to be revealed once again, it will be necessary to devise appropriate methodologies to remove it. Paint removal. in itself can be helpful as one can then assess any damage or decay that would previously been hidden.

Mechanical removal involves the paint being gently scraped off using small tools and brushes. This is easier if the paint being removed is a soft distemper. Sometimes if a harder modem layer of paint overlays the distemper, it will then be necessary to gently prize these off with small tools before getting to the soft distemper. Care must be taken to avoid any unnecessary physical damage to the plaster. As a general guide, one coat of paint should be allowed for every ten years and a greater build up of paint where relief meets flat plaster.

If paints such as oils or emulsions prove impervious to mechanical removal it will be necessary to resort to chemical paint removal. Small test or trial areas should be undertaken at various points on a ceiling to accurately determine the number of layers and nature of paint so as to evaluate the scale of work. Never assume that what the paint covers is actually plaster as it may be composition, cartonpierre or papiermache.

Presently, there are many brands of paint remover on the market, most of which are either alkaline or caustic based. As paint removers these are very successful but they are entirely unsuitable for use on plasterwork. The physical effect of such treatments can be disastrous. The products are water based and contain harmful salts which porous plas~ ter will absorb in large quantities. The high levels of water used to wash out the residues, activate the naturally occurring salts in the plaster causing a structural breakdown of the plaster as efflorescence occurs. This problem is a long term one and will reoccur any time the plaster becomes damp. Another effect is that the surface of the plaster becomes pitted and grainy. The use of caustic or alkaline paint removers can change the whole nature of the plaster and their use goes very much against the idea of minimum intervention.

A more appropriate methodology and one which was used successfully at 20 Dominick Street and 12 Hume Street, Dublin is the use of a solvent based Methyline Chloride paint remover with a wax additive to allow the solvent adhere to the plaster. This is applied directly to the surface and after some minutes causes the modem paint binders to expand, lifting off the successive layers of paint. Loosened paint can then be removed with small tools and scrapers. The exercise can be repeated until all the paint is removed down to the plaster. Once the paint has been removed, the surface should be washed down with white spirits to remove remaining residues. This method has a few drawbacks, principally being slow and laborious removal so labour costs can be high. Successive applications may be necessary if the layers of paint are very dense.

During paint removal, pieces of plaster will become dislodged, these should all be numbered and its position plotted on a drawing of the ceiling or an enlarged photocopy of a photograph.

12 Hurne Street - Free hand repairs to scrolling tendrils.
Repair work
Once paint removal has been completed, the scale of damage and appropriate methods of repair must be assessed and will depend on the type of plaster, elaborateness of design and how the detailing was originally made up - that is whether the pieces were hand modelled or cast.

Plain face mouldings such as cornices, where the damage is slight (such as large cracks or missing portions) can easily be repaired. Using a soft mixture of lime putty gauged with gypsum, the gap can be filled in flush with the original using a joint rule. However should large sections of the cornice be missing, it can be replaced by running in situ. Alternatively, a template can be used to run a cornice in gypsum on a bench or make a plaster reverse mould from which a section of cornice can be cast which can then be mortared into position afterwards. From a safety aspect, particularly in public buildings, these sections are further fixed in place using solid brass or stainless steel screws.

If the decoration was originally made up of pre-cast elements, it can be replicated by taking a silicon squeeze mould of the original either in-situ or on a bench and casting the necessary number of details before bedding these in situ. Care should be taken in the type of mortar used in fixing new work along side or between originals. Modern mortars or fillers are quiet hard and it is more appropriate to use a soft traditional mix of lime putty and gypsum.

If paint removal does not form part of the brief (either due to a lack of time or finance), it would be advisable to remove paint from the particular areas being repaired so that the new work will more accurately match the original. Decorative ceilings that were executed and modelled freehand will present a greater challenge to the restorer if missing elements are to be replaced. The restorer will have to have a good grounding in the methodologies involved, but also have the consummate skill of an artist to be able to replicate another artist's work. if such skills are not available, restoration will have to be by casting in gypsum. Rococo works which have large scale details and undercuts should be cast and bedded separately. This will help to capture and maintain the free flow and movement of the decoration.

Another common problem is where a plaster ceiling either plain or decorated has a tendency to sag or drop because of structural movement or decay in ceiling laths, detachment of the laths from the ceiling joists or detachment of the plaster key from the laths. It is possible to support or suspend the ceiling from battens fixed between the joists using stainless steel wire to prevent further movement.

The plaster key can be refixed using nylon wall plugs, which can support the plaster to the lath. Firstly the ceiling is drilled from above, through the lath on into the ceiling. From below a hole is made so as to accommodate the wall plug. Care is required not to remove all the surrounding plaster. The plug is then inserted up through to the laths and the hole in the ceding plastered over. A layer of scrim and plaster can then be applied around the plug on the lath side to secure it in position.

The method of partially or completely flooding areas of ceilings between the joists with casting plaster (still commonly used as a means of refixing ceilings) should never be contemplated. Traditional lime mortar by its very nature will expand, contract and generally move with the building. As casting plaster is a hard rigid substance when set and dry, the ceiling is effectively trapped. Consequently, the only way it can release pressure is to crack, so defeating the whole object of the exercise. Large quantities of casting plaster will also increase the weight of the ceiling and may cause collapse and the large amounts of moisture Andrew Smith along with introduced can cause the lath to expand breaking the plaster key and potentially setting up a situation of further decay.

When repainting a ceiling after paint removal and repair work it is preferable to use a traditional high porous paint, which will not clog up the detail. Oil bound distempers/paints should never be used Flat oils and traditional distempers are preferable. The ceiling at 20 Dominick Street was repainted using Classidur a solvent based highly porous minimum tension paint which can be used over any surface and only needs two thin coats so that detail does not become clogged and can also be removed with white spirits prior to redecoration.

When many of the great houses in Dublin became slum tenements during the 19th century and suffered much disruption, it is a marvel to find such a wealth of decorative plasterwork surviving today. It is therefore a shame to find that after surviving so many vicissitudes, these ceilings are now at risk from insensitive and inappropriate repair or at worst, replacement with 'faithful reproductions'.

Andrew Smith along with his partner Sean Harrington are currently engaged in the restoration of decorative plasterwork in City Hall, Dublin. They can be contacted at, Ballinakill Lodge, Kinnegad, Co. Westmeath. Tel.. [0405,31 9040; Fax[04054]6633, Mobile 0878199032.

Context 64 December 1999