CLEANING FINE PORCELAIN
It is very important that an item is clean before restoring. Once a spray glaze is used, it will seal the paint and any dirt on the piece. When an attempt is made to clean the area after restoration, damage and removal of the restoration will result.
If an item has been previously restored, strong chemicals will hurt the finish. If durable lacquer paints had been properly applied in the restoration process, then these pieces can be cleaned by using milder cleaning solutions and using a little extra care.
Reducing agents are used to remove rust stains. Because the mineral is in an oxidised state, the rust must be changed into a soluble form by the reducing action. A 5% solution of sodium hydrosulphite (sodium dithionite) is applied to the stain. It reacts with the rust making it more soluble. It may also bleach the stain. The piece is then thoroughly rinsed in water and washed in a solution of DTPA (dethylene triamine pentacetic acid) dissolved in a 5% solution of sodium hydroxide (Ph of 5.5). The dissolved iron forms a chemical bond with the DTPA that can be washed out of the object. The object must then be washed and soaked in water until all traces of the chemicals are gone. Commercial rust remover, or muriatic acid may also be used.
Because dirt is a source of deterioration, it is often necessary to remove and/or bleach it. In ceramics bleach usually means either Hydrogen Peroxide H2O2 or household chlorine bleach (Sodium hypochlorite) NaoCl.
The bleaching action of both these agents is caused by the oxidation of the chemicals that make up the stain. The color in a stain is usually rich in electrons it is more susceptible to oxidation resulting in a loss of color. While this removes the color it does not remove the foreign matter (dirt etc.) causing the stain. A prolonged soaking in water after bleaching will help to remove this dirt so the stain will not come back again.
Surface cleaning of objects to remove loose dirt and dust (from dry surfaces only) using brushes, an airbrush or photographic cans of air, the object is then washed in warm water with a mixture of Orvus (sodium lauryl sulphate) and Calgon (sodium hexa meta phosphate) to increase wetability. An assortment of sponges, brushes, old toothbrushes are also used to apply the chemicals and clean the object.
To remove the stains that occur with age and form a crazing pattern or to remove the darkness from an age crack or crack, we pour in hydrogen peroxide (40% volume) and cover the stained area or if the stain is all over, completely cover the item and let soak. It may take 10-15 minutes or 48-72 hours. Patience brings out the desired results.
Matte finishes such as bisque objects are better cleaned with hand rubbing or a soft sponge. If an object is extremely dirty, after testing, a liquid oven cleaner (sodium hydroxide) may be applied and the object again immediately scrubbed with a soft brush or toothbrush. It is thoroughly rinsed to remove all trace of the dirt and cleaner and then left to soak in water for 24 hours to remove any remaining traces of dirt or cleaners. The water should be changed frequently to remove the dirt and chemicals and prevent them being redeposited on the object.
The object is then left to dry out for several days (usually twice the amount of time it has been in the poultice) before proceeding to the next step. Chlorine bleach is not recommended for porous ceramics because of the possibility of the absorption of the chlorine into the ceramic body, causing salt crystals to form under the glaze or in any cracks. Peroxide may also react with iron in earthenware ceramics and cause iron staining. It can also affect gilding and unfired decoration. Peroxide groups may also remain attached to the stain affecting further treatments.
Instant Glues Driving You Crazy? You must realize that if you improperly glue your piece and then have professional restoration artists continue the process of restoring your broken treasured pieces, the cost is going to be at least doubled, possibly tripled and maybe even impossible to undo!
Instant glues do not do the job and require us to undo the gluing prior to our restoration process. The least vibration from being hand held is enough to off set it. The problem is these glues cure so hard that any impact sideways will cause the glue to sheer. The strength to pull on it may be there, but if it were to fall over, most likely it would come apart. Another negative quality of these glues, is that they weaken over time. Many times we have tested the strength only to find the item falls apart only after a few months. Just the slightest pressure may have it come apart. And finally, these glues, over time will yellow and the crack, in some cases will become apparent. Then our professional restoration artists use their skills of opening up the crack, filling it and then with an air brush, to simulate the design and glaze, will be able to cosmetically hide the damage. If an item is not glued to the professionals standards, then it will be more costly to undo the glue and restart.
Modern adhesives used to reattach the pieces, epoxies, acrylics or urethane are matched to the weight, color and future uses or the repaired article. Most, while very expensive and not readily available, will not yellow, weaken, or further damage the object. The clearer the adhesive the longer it takes to bond and cure. The adhesive most recommended for use with ceramics requires 7 full days to set and 3 months to cure. When an invisible mend is required, this is the adhesive of choice. Other adhesives require 7 to 30 days to cure. In filling and painting should not start until the chemical reaction of curing is complete.
If an object is missing pieces then replacement parts have to be made. If the object has similar pieces then a mold is made from these pieces. The mold can be dental wax, dental molding material, latex rubber compound or any other similar flexible molding material. The material must be able to mold fine detail, release little heat, and set easily without contracting as it sets and cures. If any residue is left on the object it must be easily removable. After a mold is made the new part is then cast. A casting resin (usually 2 part) that closely matches the density hardness and if possible the color of the object the part is for is used. Most resins will allow us to add some color to them before mixing. It is important again that there be a little shrinkage as possible when the resin is set. Bulking compounds such as fumed silica and micro balloons can also be added to the casting resin but they tend to weaken and lighten the cast object.
Once the part is made it is attached to the object and is treated as if it were a piece that had been broken off. Painting the part can be done before or after attachment which ever is easier. It is painted with the same paints and in the same way as a repair is.
If a part is not available to mold then a new piece must be sculpted. The best available material at this time is an epoxy putty. Miliput and Hexcell both are light colored easy to sculpt and easy to sand and carve after curing. Both putties can be sculpted with solvents or water while they are pliable and are easily removed from the skin. The open time varies with the temperature but is usually 30-60 minutes. Once the part is sculpted it is then left to set either on the object or separately. If the part is small it is best to reglue the piece to the object to make sure that it will not break off in the future. Once the part has set it is carved and sanded until it matches the missing area. It is then treated in the same manner as the cast piece was.
Materials used in in-filling are similar to the adhesives. They also take weeks or months to cure properly. Some may be worked faster, but the are unforgiving and if a mistake is made the in-filling must be removed and the process restarted. Some cracks or breaks will require 3 or 4 separate in-fills to completely cover cracks of most breaks. The in-fills are sanded, usually by hand with 220 to 1200 grit glass sandpaper. Such fine sandpaper doesn't damage the glaze around the break or the rest of the object. The sanding may take days or weeks depending upon the size and shape of the in-fill.
Painting a repaired object can be done in several ways. The accepted technique is to airbrush the repaired area with a base coat usually white but it may be tinted to match the color of the ceramic body. And then either paint or airbrush the color that was originally applied to the objects surface. This coating is either applied as lacquer enamel, water-based acrylic paint, oil paint, or a pigment dispersed in a coating.
The object is then ready for the first coat of paint which is the background color. After the paint has dried, all of the cracks and chips are re-examined. Minute crack lines and pinholes will now be visible the paint is removed from those sections, the cracks filled in, sanded and the background repainted. The paint is applied in several layers, each layer is carefully sanded and polished before the next layer is applied. When the background is complete the remainder of the paint is done one color at a time. Each color and/or layer takes 3 to 5 days to paint, dry and sand. After the final color, the object is ready for glazing. The glaze is sprayed on in a number of thin layers that attach to and become part of the paint. Each layer is sanded and cured for 3 to 7 days before the next layer is applied. When the weather is wet or humid, it takes much longer to cure. Invisible mending takes more time, as each step has to be done to a more meticulous degree.
The glaze is the final coat. It must be a clear coat that will stand handling and not yellow. It must be washable and resist ultraviolet light and heat. The glazing material is usually chosen to match the type of paint that is used. The glaze is sprayed on in a number of thin layers that attach to and become part of the paint.
The glaze is sprayed on in a number of thin layers that attach to and become part of the paint. Each layer is sanded and cured for 3 to 7 days before the next layer is applied. When the weather is wet or humid, it takes much longer to cure. Invisible mending takes more time, as each step has to be done to a more meticulous degree.
CARE AFTER RESTORATION
*Never immerse in hot water;
*Clean with soft cloth or feather duster, do not use chemicals;
*Restorations are for decorative purposes only, do not use for serving food;
*Keep from any source of heat including direct sunlight.
IF YOU READ THIS FAR, I COMMEND YOU! IT IS A LONG, HIGHLY TECHNICAL AND PRECISE PROCESS TO BRING A BROKEN TREASURE BACK TO LIFE BUT WELL WORTH THE REWARDS OF ENJOYMENT. THANK YOU FOR TAKING THE TIME TO READ OUR LENGTHY PROCESS.