TACS Conservation Information Sheet No. 2
Decorative ceramics are amongst the most stable group of artefacts in any collection. They are relatively sturdy, and if left untouched, very durable. Moving, handling and poor storage present the greatest risk to tile collections. This data sheet is aimed at helping, in the first instance, to prevent any damage to tiles, but if damage does occur, carry out simple repairs using safe materials. This 3 page data sheet considers:
Do not store tiles flat, one on top of the other, downward pressure can cause the tiles at the bottom of the heap to fracture. Storage in this fashion also encourages handlers to attempt to remove tiles from the bottom of the pile without first moving the ones at the top.
Do not put sticky labels on tiles, the glue can stain or damage the surface.
Do store tiles upright on edge in racks or boxes appropriate to the size of the tile
Each tile should be individually wrapped in acid free tissue paper, with a slip of bubble wrap or corrugated cardboard, cut to size, between every tile
The outside of the box or rack should be clearly marked with a number plan and inventory of the contents of the box or rack. This will deter handlers from ’flicking’ through the upright tiles looking
for particular examples and causing possible impact damage in the process.
Wrapping or unwrapping a tile from the acid free tissue should be done on a flat surface or table. Never unwrap a tile in the hand. Always have a space already cleared where you can put your tiles.
Do have clean hands when handling, as dirt can be absorbed into porous bodies.
Do pack into strong boxes (in the same way as described for storage), using plenty of packing to avoid any movement of the tiles within the box, if you are to transport your tiles any distance at all
Do not clean tiles with ordinary tap water, this will almost always cause salt growths which can damage the structure of the tile between the glaze and the body
Always use distilled water with a little gentle non-ionic detergent, such as ’Biotex’ or ’Ariel Liquid’. Any national museum with a conservation department will tell you which commonly used detergents are non-ionic.
Soak a cotton wool pad or cotton bud in the solution and gently clean the surface of the tile. When the dirt is removed, wipe the surface in the same way with plain distilled water, leave the tiles to dry on absorbent paper. When dry, gently buff with dry cotton wool.
Broken edges that have absorbed dirt can be gently cleaned with a soft tooth brush. Be aware that the glaze near the break may be fragile or loose.
Do use white spirit to remove sticky labels.
If tiles have been in a smoking environment, e.g. a bar or hotel lounge, they may have a brown tar film over the surface, this can be removed with methylated spirit.
If tiles are smoke damaged from fire they can be left to soak in distilled water until the smoking has leached out. This may take three to four weeks with frequent changes of water when it has become brown and dirty.
Rust stains can sometimes be removed by gently cleaning the affected area with a cotton bud dipped in a rust inhibitor that contains Phosphoric Acid. Rinse in distilled water afterwards.
Many organic stains can be removed with a poultice of Hydrogen Peroxide 20:100 volume (available from chemists) Always soak the whole tile body in distilled water first before applying the poultice, if the body is dry the stain may be drawn further into the tile.
Do not use household bleaches, they can cause crystallisation under the glaze.
Do not use alkaline cleaners, they may affect blue glazes.
Do not use acid cleaners, they may affect red glazes
Do remember that all stains are difficult to remove, and some may be permanent
Do not coat your tiles with any sort of plastic or polymer sealant, most are impossible to remove and will eventually crack, craze and discolour. Beeswax or linseed preparations are equally difficult to remove, they attract dirt and will eventually turn black. If a title is unglazed and particularly porous it may be coated with a thin application of microcrystalline wax. This gives a hard coat and will not turn yellow.
Do as little to your tiles as possible, allow them the dignity and beauty of their age.
If a tile is broken:
Do wrap all of the fragments in acid free tissue immediately, they will then be kept clean until mending can take place.
If you repair an old mend then all old glue must be removed by soaking in warm distilled water.
Do not use an inappropriate glue for your repair, a glue must never be too strong, its strength must not be greater than that of the tile body, and it must have an easily available solvent.
Recommended glues are Paraloid B-72 or ’Conservation Adhesive’ (Koob, Studies in Conservation, 31, 1986) or those in the cellulose nitrate category.
Do not use an excessive amount of glue. The thinnest smear on both surfaces will suffice, press the broken pieces together for a few seconds, place on a flat surface and leave for 24 hours to set.
Do not glue more than two fragments together at any one time. Gluing should not be rushed. Clean off any glue on the surface of the tile with a little acetone.
The aim of any conservation repair is a clean, neat and tidy join. It does not have to be invisible.
When displaying a single tile a wood frame around the tile with a hanging device fixed to the wood is effective, however, a simple and more importantly, easily reversible, method for mounting tile panels is as follows:
Cut a piece of ¾” thick blockboard (or a non-flexing board) to a size a little larger than your tile panel. Cover the face of this board with strips of balsa wood, glued with a wood adhesive at intervals corresponding with the joints in your tile panel. The balsa wood should be at least 3″ wide to allow the edges of adjoining tiles to fit comfortably over the balsa.
The tiles may then be fixed to the balsa with a small amount of reversible glue or adhesive only at each corner of the tile.
When set, cover the edges of the panel over with any framing material.
To remove your tiles from the panel, take away the frame, and using a scalpel blade with a handle or a craft knife, slice into the sacrificial balsa wood layer at the points where the tiles are glued. Lift off the tiles and either carefully trim away any glue and balsa from the back of the tile with your scalpel, or soften and remove the glue with a solvent.
Copyright: Lesley Durbin Jackfield Conservation Studio April 2006
The above information is for guidance only.
We do not accept responsibility as a result of any person carrying out any works according to the advice contained in this document