Of course, to accomplish this requires skill and a wide variety of glass working tools. Such repairs are not for the amateur, but must be done by a professional with a properly equipped shop. What a good glass repairer can accomplish in eradicating blemishes caused by time and use is almost incredible. With grinding and polishing wheels he can remove all traces of nicks and chips.
Take, for instance, a goblet, wine glass or flip glass marred by a slight nick on the rim. Skillful grinding and subsequent polishing will cause this to disappear entirely.
The same repairman can also regrind a glass lamp base that is not in first-class condition because careless handling through the years has resulted in slight chips along the lower edge. The same can be done with a piece of lacy Sandwich or pattern glass.
Closely related to this work is a repair possible with decanters. Sometimes a stopper of the same type and period as the bottle does not fit properly. If it is too large, the repair is relatively simple. The base of the stopper can be ground smoothly and evenly until it fits the neck of the bottle. Even the opening of the latter can be slightly enlarged by grinding. If the base of the stopper is too small, a sleeve of glass must be applied and then ground so that a firm fit may be insured. This repair is naturally not as successful, for it is always obvious.
In fitting decanters with replacement stoppers, be sure that they match in tint. In the case of Irish glass, for instance, that made in the Waterford district had its particular cast of color, a slightly smoky, bluish tint; that from Cork, a straw or amber tone. These fine differences in tone are only apparent to the average observer by close comparison; but if a stopper from Cork were to be fitted to a decanter that originated in the Waterford section, this slight difference in tint would immediately be emphasized and the original purpose defeated.
In grinding and polishing glass to remove slight chips and nicks, one should be sure that the piece so treated is rare and fine enough to warrant the expense of restoration. There is also the off chance that the piece may break or crack in the process. For example, a Stiegel-type sugar bowl has a very slight chip on the finial of the cover, and is therefore not in perfect condition. Shall the owner run the remote chance of the cover breaking during the process of having this small blemish ground and polished away, or shall he "bear the ills he has?" It all depends on the temperament of the owner. The chances of the cover coming through in perfect condition with blemish completely smoothed away are probably ninety-nine out of a hundred. He must be prepared for the one ill chance, however, even at the hands of a glass grinder of skill and long experience, and accept it, should it happen, as a contingency incident to the work.
Sometimes a piece of old glass is quite free from nicks or chips but the surface has begun to disintegrate, giving a slightly cloudy or frosted appearance. If it has gone beyond the initial stages it is an example of sick glass, and such it must remain. There are two causes for sick glass. Either the proportions of the batch from which the piece was made were incorrect, or the piece has oxidized from chemical reaction. The latter may have been due to the glass having been left for years in a damp cellar, having been buried in the earth, or having been used overlong as a container for some liquid.
Extreme examples of sick glass are sometimes very beautiful, such as the irridescent pieces recovered from Egyptian, Grecian, Roman or other ruins of the early civilizations of the Mediterranean. It was these delicate colorings that the late Louis Comfort Tiffany sought to accomplish in his favrile glass by the addition of various minerals.
If all sick glass resembled Mr. Tiffany's favrile productions, it would present no problem. Unhappily, there is seldom any irridescence, but only a cloudy, frosted tone, making the piece look sick indeed. In the initial stages, this condition can be rectified by repolishing, provided both sides of the piece can be reached. The surface is thus cleared of the damaging cloudiness. Plates, bowls, drinking glasses and similar shaped pieces lend themselves to this treatment. If the disintegration is only on the surface and has not permeated the material, such work is usually permanent. Otherwise, it is of only temporary benefit and the telltale cloudiness shortly reappears.
Old flasks and bottles, even with a mild attack of this malady, cannot, because of their shape, be sent to the repolisher, since he has no means of reaching the inner surface of the glass with his bluffing and polishing wheels. On the other hand, some collectors have developed an ingenious technique for treating bottles so afflicted, and it is reasonably successful. Take a pliable green twig, and attach a swab to one end. Dip it in a good grade of clear, colorless mineral oil and patiently work it around inside of the bottle. Rub each cloudy spot until it disappears under the action of the oil. A bottle or flask so treated must then be tightly corked and kept so, because the cloudiness will return as soon as the oil has evaporated. I have seen flasks that have been given this oil treatment and remained clear for upwards of five years, even though kept on a shelf in a window and thus exposed to a maximum of sunlight.
This treatment is, of course, only a palliative and not a cure. Sometimes, too, the oil finally gives the glass a slightly yellow cast. A problem not in the nature of a repair or restoration but one which often faces the bottle collector, is that of cleaning pieces disfigured with a dried sediment. If this does not respond to thorough and liberal doses of good soap and water, fill the bottle with either a mild acid or alkaline solution, and let it stand for a day or two. It may be necessary to use first one and then the other. If the sediment is of an acid nature, the alkaline solution will produce a chemical reaction that will loosen it; if the substance is alkaline, the acid solution will have the desired effect. In no case should a powerful reagent be used. Vinegar and washing soda, both inexpensive and mild, are excellent reagents.
If sediment still remains, there is a further course of action. Fill the bottle about a quarter full of clear water and add about two tablespoons of fine steel shot. Cork the bottle and shake it thoroughly. This scours the inside effectively. If shot is not available, clean bird gravel used with less water can be substituted. Never use lead shot. It is not sharp enough to be effective, and besides if there is any trace of chemical in the bottle the result may be a coating of lead solution. This is not only difficult to remove but, in extreme cases, can practically ruin the bottle or flask.
Another good method of removing stubborn sediment is to fill the bottle with a strong solution of lye and cold water. Let it stand for two days. Paint, wine dregs or vinegar stains will soften and can then be removed with a brush or the usual quantity of steel shot. If the outside of the bottle is also stained, use the same solution for cleaning that, and finish by washing the entire bottle in soap and water. Brilliant, sparkling glass should result. This method is used by one of the foremost collectors of American glass bottles and flasks in this country.