What Constitutes a Flaw?


Most dinnerware and glassware departments and specialty shops have had trouble at one time or another with customers who seek flawless perfection in the glassware merchandise they buy.

Perfection and "sameness" in glass can be achieved only in assembly-line products. It is not possible or even desirable in quality ware whose manufacture depends so much on the skill and artistry of individual craftsmen.

Slight variations and tiny imperfections in hand-made glassware pieces are actually a confirmation of craftsmanship and individual artistry. Most customers who appreciate good glassware understand this. For those who don't, here is a series of questions and answers that a salesperson can use to promote better understanding of the product.

Does a "seed" or bubble in glassware constitute a flaw?

No. One of these tiny "seeds" or bubbles the size of a pinpoint may sometimes be observed in a piece of glassware when it is examined closely against a strong light. The bubble is formed by gases when chemicals are united in the fusing or melting of the raw ingredients. It does not affect the quality or beauty of the glass.

Should all pieces in a set be exactly alike?

No. There are almost always slight variations in diameter, height, and other dimensions in any group of tumblers, goblets, plates or other articles of glass. These variations are so slight that they can be detected only with a micrometer, rarely by the naked eye. This is the hallmark of fine hand craftsmanship, almost assuring that each piece has been made individually.

What is a cord?

A cord is an almost invisible difference in density in the glass which occurs during the fusing of the molten glass. It is visible only by reason of the fact that it reflects light. When a goblet with a cord in it is filled with water, no light is reflected and the cord becomes invisible.

Is a mold mark a sign of imperfection?

No. A mold mark is merely a ridge on a molded glassware piece that indicates the point at which the mold that formed the item was separated for removal of the finished ware. If it is overly prominent, however, it may be an indication of careless workmanship.

What is a shear mark?

A shear mark is a slight puckering of the glass caused when the artisan snips off excess molten glass when shaping the piece, as for example the end of the handle of a pitcher. It is a normal characteristic of glass and should not be considered a flaw.

How can the salesperson and the customer judge the quality of glassware?

There are certain simple tests and guides. Look for clarity and luster by holding the piece against a pure white background. Good glassware is quite clear, while inferior grades show a cloudy bluish or greenish tinge. Quality glassware is also marked by a permanent polish or luster that results from fire polishing.

Look for smooth edges. Glassware edges should be even, never rough and scratchy. In hand-cut ware, the design should be sharp and accurate. In etched ware each tiny detail should be distinct and clearly defined.

Why can't small irregularities be entirely eliminated from hand-made glass?

For the very reason that the glass is hand-made. No matter how deft the touch of the sensitive hand of glass craftsmen, it is impossible to eliminate completely small variations. These should not, therefore, be considered flaws. Glass is one of the trickiest materials to work with. Even machine-made glassware cannot be made absolutely perfect. But consider this: even the finest diamond examined under a jeweler's loupe rarely reveals absolute perfection.

Fine hand-blown glass frequently contains lead, which improves its clarity and adds to its weight. If a piece of stemware rings with a clear musical tone when struck lightly, this indicates lead content. Lime glass, on the other hand, does not have this resonance. But this does not make it any less desirable. The lime in such glass adds to its toughness and strength.

What is that indentation on the bottom of a hand-made pitcher?

A pontil mark is the confirmation that a piece is hand-made. The indentation is where the glass was attached to the pontil in the final step of the fire polishing. Some hand-made glassware is attached from the bowl end with the glass cut away at the rim, leaving no indentation.

Is hand-made glassware really made by hand or merely hand-finished?

The production of hand-made glassware is indeed a hand process. The skilled hands and eyes of many men and women working in teams go into the making of every piece. The amazing thing is that such a high degree of excellence can be attained, that piece after piece coming from the individual group of glass blowers or pressers is so nearly and accurately a duplicate of every other piece.

Reprint of article in September 1982 issue of China Glass and Tableware.