Monitoring Desalination of Ceramics Results After Treatment Art Conservation

Test

Earlier beginning whatever treatment, thoroughly examine the ceramic, noting:

• the condition of the ceramic body;
• the extent of previous repairs;
• any unfired ornament or blistering, weak and flaking glaze; and
• the presence of stains and residues.

Pay particular attention to any unfired ornament or weak and flaking glaze, considering if these are undetected they could exist damaged during treatment. Note the presence of any stains and residues equally these indicate the history and use of an object and, depending on their significance, it may be appropriate to retain them. Employ notes, drawings and photographs to document the status of the ceramic earlier information technology is treated. Record all observations and pertinent investigations.

Cleaning

As cleaning removes dirt which could otherwise be embedded further during subsequent handling stages, information technology is usually the starting time stage of a conservation treatment. Cleaning techniques which may be applied to ceramics include:

• brushing;
• vacuuming;
• wiping with damp swabs; and
• wet chemical cleaning.

Start the cleaning procedure by using the most gentle and least toxic materials. Always attempt dry cleaning before wet or chemic cleaning. Remove loose dirt using a brush and gentle vacuum suction. Wooden sticks will remove accretions and some of the more than stubborn dirt. Do not use metal probes as they are probable to cause damage.

Do not wash objects with flaking glaze or soluble painted decoration and if extremely fragile do non brush them. Clean robust sections of vitrified glaze on such objects using clammy swabs. Never fully immerse ceramics in water, as cracks in the coat could retain h2o, leading to further damage.

Test any solvents to be used on an inconspicuous area and on decoration or gilding before application.

Some dirt can be removed using cotton swabs moistened in distilled or deionised water. Roll the swabs over the surface. Do not scrub them back and along. To remove grime, use a solution containing a few drops of a full-bodied, non-ionic detergent (such as Lissapol) in water (100 ml).

Alternatively, prepare and use a pure lather solution equally outlined below:

• dissolve one gram (about 1 teaspoon) of pure soap flakes in a little hot water;
• add together enough cold water to make a total of one litre of solution;
• add together 100 ml of soap solution to 100 ml of h2o;
• apply with a cotton wool swab by rolling over the ceramic surface; and
• remove detergent or soap residues using cotton swabs moistened with distilled water.

This method is particularly suited to small intricate objects and porous, unglazed ceramics.

Poulticing

Poulticing is also suitable for cleaning porous, unglazed ceramics. The steps in preparing and applying a poultice are detailed below:

• tear acid-free blotting paper into small-scale pieces;
• wet the paper with distilled water;
• mash the wet newspaper blend to make a lurid. A heavy-duty domestic blender is a very effective 'masher'. Annotation that a large amount of water needs to exist added to the paper for correct performance of the blender (virtually 300 ml of wet paper to 1500 ml of water);
• drain excess water from the poultice, using either a strainer or hands, before applying;
• cover the ceramic surface with an acid-gratuitous tissue to avoid the newspaper pulp becoming trapped in the ceramic pores;
• utilise the poultice. As it dries it absorbs dirt from the pores of the ceramic;
• cover the poultice with a polyethylene sheet if the relative humidity is low. A poultice which dries too rapidly may not exist effective;
• leave the poultice to dry completely and autumn abroad; and
• several applications may be required to make clean the ceramic surface satisfactorily.

Wash ceramics which are sound, glazed or less porous using a more conventional method, as outlined below:

• use a big plastic container or line a sink with towels and launder just one object at a time;
• utilize cold or warm water (1 L) which contains either a concentrated, non ionic detergent (1 ml or 0.25 teaspoon) or 100 ml of soap solution (see above for preparation);
• utilize small brushes to remove stubborn clay;
• rinse the ceramic thoroughly with distilled water; and
• bleed the ceramic on cloth or paper towelling and dry it with a soft cloth.

Stain Removal

Always test potential solvents on an inconspicuous part of the ceramic to ensure that they have no adverse furnishings. Try solvents such as methylated spirits, alcohol and acetone on stubborn stains. Utilise these with cotton wool swabs. If using acetone, take care, avoid contact with peel, wearable eye protection and exercise not inhale the vapours.

On porous, unglazed ceramic surfaces, use a paper poultice prepared with tissue newspaper and the called solvent. To slow the evaporation of the solvent, comprehend the poultice layer with plastic film.

Remove stains found in the lesser of former tea cups and in cracks past using oxygen-releasing detergent powders. These powders, which are frequently marked 'Contains Oxygen Bleach', contain sodium perborate, which is converted to hydrogen peroxide in water. To remove these stains:

• prepare a 2 % solution by dissolving 20 1000 of powder (about one tablespoon) in ane L of water;
• leave the porcelain or other glazed ceramic in the solution for about two hours;
• check the object periodically, brushing the stained area gently at these times;
• begin the treatment in the forenoon and continue until the stain is removed;
• if necessary, store the ceramic in clean water overnight and place it in fresh bleaching solution the post-obit day;
• when the stain has been removed, rinse the object thoroughly past soaking information technology in distilled h2o for 2 hours; and
• bleed and dry the ceramic.

Although information technology is more expensive than the oxygen-releasing detergent powders and has a limited shelf life, hydrogen peroxide is effective in removing stubborn stains from porcelain. Always test decorative elements get-go to make sure they will non be affected. If there are no adverse furnishings and so apply hydrogen peroxide as described below:

• pre-soak the porcelain in distilled water before applying the hydrogen peroxide;
• lightly curl some cotton wool and soak it in 3 % v/five hydrogen peroxide. Upwardly to 30 % hydrogen peroxide solution may be used;
• place the swab directly over the stain, leaving it in identify for two or three hours;
• check periodically, repeating the process until the stain is removed;
• if the treatment needs to keep the following twenty-four hours, identify the porcelain in water overnight and and then go on the application of hydrogen peroxide until the stain is removed;
• rinse the porcelain thoroughly by leaving it to soak for two hours in distilled h2o; and
• allow the porcelain to drain and dry out.

Equally hydrogen peroxide is a very powerful oxidising agent, wear rubber gloves and center protection when using information technology.

Copper and iron stains may result from clamps or dowels used in old repairs or from contamination on burying sites. Removing these stains is difficult and requires the use of stronger chemicals. Consult a conservator earlier attempting handling of these types of stains.

Desalination

If a ceramic shows signs of salt impairment (see Deterioration before) it must exist desalinated. For ceramics with a friable surface, poulticing is recommended, rather than washing. Utilise a fine tissue that will not 'take hold of' on the ceramic surface before the paper lurid is practical (see Poulticing above). In the case of very friable ceramics seek advice from a conservator.

Porous ceramics whose surface is non friable should be wet gradually to avert further damage. This may exist achieved past:

• placing the object in a large plastic container, adding enough tap water to encompass the base of the ceramic and roofing the container with a tight-fitting chapeau;
• check the ceramic periodically;
• water will be fatigued up into the ceramic by capillary activity, allowing air to escape;
• add more h2o, up to the 'moisture mark' on the ceramic; and
• go along this procedure until the object is submerged. Desalination then proceeds.

Proceed objects wet that have been recovered from clammy burial (terrestrial) or underwater sites until desalination can begin. Transport them in individual, sealed polyethylene bags, with some wet sand or water to cushion them. Place the bags in rigid containers, then transfer the objects to plastic containers, buckets or tubs for treatment. Proceed containers covered to avoid evaporation of the wash solution.

Desalinate ceramics recovered from marine sites by following the government beneath:

• place the ceramic in a 50:l seawater/tap water solution for ii weeks;
• transfer to pure tap h2o and leave for four weeks;
• transfer to distilled or deionised water and wash until no more than chloride salts are released. This will involve periodic changes of solution after several months in each bathroom; and
• if slime forms on the ceramic, indicating that bacteria are active, add a biocide to the wash solution. Consult a conservator if bacterial contamination is suspected.

The time required to complete desalination varies greatly from object to object. Ideally the chloride content of the solutions should be monitored and the solutions changed when the chloride levels in solution have stabilised. This procedure requires admission to sophisticated equipment. A simpler approach is described below.

Every bit a general guide, test for chloride salts each calendar month and alter the solutions if salts are present in the wash solution. To examination for chloride salts, utilise the following process:

• place ii ml of launder solution in a test tube;
• add together ii drops of x % west/5 nitric acrid to the wash solution;
• add two drops of silver nitrate solution to the nitric acrid/wash solution. The silver nitrate solution is prepared by dissolving about 15 g of silver nitrate in 100 ml of distilled h2o;
• if a white precipitate forms, then chloride salts are present. Change the wash solution and go along desalination for a farther month; and
• continue washing until tests show that no chlorides are nowadays (four to five months in most cases).

Previous Restorations

Previous restoration attempts may be indicated by the presence of big metal staples, dowels, glues, resins and fills. Staples and dowels are usually left in identify as removing them can cause damage. If, nonetheless, they are corroding and damaging the ceramic, treat them to stop the corrosion or remove them. Contact a conservator for advice on the about appropriate procedure.

Adhesive repairs and residues are normally credible as they often get xanthous and unsightly over the years. Some common adhesives used to repair ceramics include starch paste, animal glues, shellac, cellulose nitrate, soluble nylon, epoxies and emulsions such as PVA. Depending on the type used, old adhesives tin often be redissolved. Unfortunately the solubilities of many adhesives change equally they age. Soluble nylon, for instance, is probably meliorate referred to every bit insoluble nylon! Comprehensive information regarding the preparation and properties of consolidants, adhesives and coatings is provided elsewhere (Horie 1987).

A conservator tin provide advice regarding adhesive type and solubility. If solvents are used to soften or deliquesce adhesives, ever exam painted surfaces to make sure they will non be affected.

To test the solubility of an old agglutinative, follow these steps:

• carefully cut a small-scale flake of adhesive with a sharp scalpel;
• place it in a covered drinking glass container;
• soak information technology in h2o initially;
• if the adhesive does not dissolve in cold water so try warm water, booze (ethanol) or methylated spirits (95% ethanol and 5% methanol) and acetone (in that lodge);
• stronger solvents are needed to soften and/or dissolve adhesives like epoxy resins. Consult a conservator earlier attempting to remove these agglutinative types; and
• if a scrap of adhesive cannot exist removed then utilize the solvent to an exposed spot of adhesive and annotation its effect.

Take the usual precautions (rubber gloves, middle protection and non-inhalation of vapours) when using organic solvents such as acetone and alcohols.

To dismantle an old repair, try the following techniques:

• work on a padded surface, or line a container so that pieces that fall apart volition not be further damaged;
• keep an authentic tape of each fragment'southward position in the ceramic and so that subsequent reconstruction volition exist easier;
• paint the solvent repeatedly over the joins while very gently manipulating the fragments to test for whatsoever motion;
• when using alcohol, methylated spirits or acetone, cover the joins with cotton wool wicks soaked in solvent. Identify the object in a plastic container with a tight fitting lid;
• make clean excess adhesive from the edges of separated fragments while the adhesive is still soft (apply a stiff brush dipped in solvent or a sharpened stick). Take care not to remove any of the clay material; and
• go out fragments to dry.

If it is necessary to completely immerse the bring together in solvent, moisture the porous ceramic gradually. Avert total immersion in acetone or alcohol if possible, due to the cost and exposure to the solvents themselves. Consult a conservator if this step is deemed necessary.

Joining

Adhesives selected for joining ceramics should be reversible and take skilful ageing properties. They should be able to be redissolved if necessary, should not yellow, become brittle or lose adhesion with age.

Sure acrylic and polyvinyl acetate adhesives meet the higher up criteria and are suitable for ceramic repairs. Paraloid B-72, an ethyl methacrylate and methyl acrylate copolymer, has been used widely (Koob 1986) and UHU All Purpose Agglutinative, a polyvinyl ester, has shown good results. Both adhesives can exist removed or diluted with acetone. Paraloid B-72 is available from conservation materials suppliers and UHU All Purpose Adhesive is available from art materials or stationery suppliers.

Joining fragments requires both skill and patience, equally illustrated in the post-obit procedure (encounter also Figure ii):

• take a practice run of the joining sequence, holding the fragments together with tape (no agglutinative). Record the joining sequence to ensure that no fragments are locked out of the structure (meet below for more details);
• degrease all broken edges earlier joining. Apply methylated spirits (or alcohol) with a minor cotton swab. Accept care to remove whatsoever cotton fibres that may cling to the broken edges;
• prime number porous ceramic fragments with a dilute agglutinative solution earlier joining together. Dilute the agglutinative with an appropriate solvent by mixing i office adhesive to four parts solvent. Brush the dilute solution over all broken edges and allow to dry;
• to repair a broken ceramic vessel commence past joining the base fragments and go on upwardly;
• small fragments can ofttimes be joined together get-go to make a few large fragments which tin can ultimately be fitted together;
• utilize a sand tray to support ceramic fragments while the adhesive dries. Use only clean white sand and identify a piece of soft tissue under the ceramic;
• stand the larger of the ii fragments existence joined in the sand - the weight of the other fragment (if correctly balanced) will tighten the join;
• select 2 fragments to be joined and apply agglutinative along the eye of i edge;
• button the fragments together and pull apart slightly to check for an even distribution of agglutinative;
• press the fragments together and manipulate to become the correct position. Running a fingernail across the join can help to check for a good fit;
• should the join need realigning, utilise solvent with a brush to soften the adhesive and let time for adjustments;
• remove excess adhesive while still wet, or semi-dry, with an appropriate solvent or if necessary with a abrupt scalpel when dry. Utilise a minimum amount of solvent to forestall weakening of the join; and
• use a suitable tape beyond the join, on both sides of the ceramic and get out the fragments supported in a sand tray until the adhesive sets.

Work methodically so that fragments are not locked out at the end of reconstruction. A practice run of the joining sequence should ensure this. Use a tape which will non bond likewise strongly to the ceramic for the exam run. By doing this no adhesive balance will be left backside nor volition the ceramic surface be damaged when the tape is removed.

Figure ii: Repair of a ceramic dish
(a) The materials used for the repair.
(b) Application of Paraloid B-72 adhesive to the broken sides of the dish.
(c) Adhesive tape holding parts of the ceramic dish together until the adhesive sets.

Some of the self-agglutinative (pressure level-sensitive) tapes available from jotter or art suppliers are suitable. Archival quality paper tapes, which are cocky adhesive and force per unit area sensitive, are preferable merely these are only available from conservation materials' suppliers. They range from strong, thick paper tapes, such as Filmoplast P90 and Tyvek Tape, to finer tissue paper tapes, such as Certificate Repair Tape and Filmoplast P. Do non apply record to delicate glazes, painted decoration or friable, unglazed ceramics.

Dowelling is not mostly recommended equally it involves removing office of the object by drilling holes. If an object is besides heavy to be joined with an adhesive, display it on a back up which holds fragments equally if they are joined.

Gap filling is not always necessary, as there is some tolerance for loss in artefacts. If ceramic loss is visually disturbing or provides structural problems, filling may exist carried out. Note that the aim should non be to make the object await new. Restrict filling and in-painting to areas of loss and do not cover original parts of the object. As filling and in-painting crave considerable practice, seek communication from a conservator if you consider these treatments necessary.

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Source: https://manual.museum.wa.gov.au/conservation-and-care-collections-2017/ceramics/treatments

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