Clean and Bleach Your Antique Ceramics to Good Health! (Part 2)
Clean antique pottery,porcelain
repair,restoring and caring for an antique
Have you discovered that your ceramic item still exhibits grime even after
a thorough cleaning? Well then, it will require bleaching—either completely,
or in certain areas only. This is a process that can be attempted by yourself,
provided you know what you are doing and do not damage your valuables further!
Far more prudent would be to get your work done by a professional or an
experienced local conservator.
Bleaching is a method that requires patience and time. Additionally,
you have to be very clear about whether your precious pieces are really
going to be helped by this process or not. Or you can just let it be,
since antiques age with time anyway. But for the sake of putting your
mind at rest, here is an explanation of what it is all about.
(1) Is it just a small portion that needs to be bleached? It requires
the application of a special paste (chlorine-type abrasive cleaning powder
plus water). The paste is to be left on for a few minutes. Then, the object
is thoroughly rinsed. A soaking for 24 hours will ensure that all traces
of the paste are removed.
(2) A longer duration is required if the entire piece is to be bleached.
The paste/poultice is a combination of hydrogen peroxide (35%), ammonia
(ratio of 1 teaspoon per cup of peroxide) and flour (ratio of two heaped
tablespoons per cup of peroxide). This is known as a 100 volume paste
where the ammonia acts like a catalyst (aids in faster reactions). The
paste can be made even stiffer with the addition of more flour. Application
can prove difficult, however, if it is too solid.
(3) Once this poultice has been applied with the aid of a rubber spatula
or a hair colorist’s brush, the piece is wrapped in polyethylene (lightweight
thermoplastic) and left in peace for a week. The plastic keeps the paste
moist.
(4) When the week is up, the item is unwrapped and soaked for around half-an-hour
to one hour in a solution of hot water and chlorine bleach (half-a-teaspoon
of bleach per gallon of water). Once all traces of the poultice are removed,
a thorough rinsing is given under warm running water. At the same time,
a brush or soft cloth is to be used for the final gentle dusting. In the
case that the piece is extremely delicate, the bleach can be dispensed
with; just plain water will suffice.
It may so happen that you wish your porcelain to be restored faster.
Well, there is a rapid process of bleaching available too.
(1) An enamel or ceramic container is taken—large enough for the item
not to come in contact with the sides. After a cloth is placed at the
bottom, a solution of peroxide (available at a hairdresser’s shop) plus
a few drops of ammonia (catalyst) is poured in. With the object placed
inside, the solution is brought to a boil. Of course, the temperature
is raised slowly and steadily. The stains on your antique disappear after
a few hours.
(2) During the process, if the level of peroxide lowers due to evaporation,
it can be replaced with heated peroxide (always keep it ready).
(3) Good ventilation is essential to get rid of the fumes.
(4) Let the ceramic remain in the solution till it has cooled down; removing
it immediately will cause damages due to temperature change.
(5) A soaking in warm water for the next 48 to 72 hours follows, to get
rid of residual grime and bleach. Of course, a colorist’s brush can be
used too, and the process repeated several times.
(6) The next step is drying. This can take several days, but it is necessary
to ensure that no moisture gets a chance to seep inside.
Some precautions, however, are necessary to be kept in mind—
(a) Earthenware and peroxide are not compatible, as iron staining may
result.
(b) Peroxide can have adverse effects on unfired decorations and gilding.
(c) Peroxide groups may decide to stay attached to stains (which will
necessitate further prolonged soaking in plain water).
(d) Porous ceramics might absorb chlorine bleach and bring about the formation
of salt crystals under the glaze or in any cracks.
