by Paul Crist Professional Stained Glass  1986

Tiffany was certainly the popularizer, if not the originator, of the leaded glass lamp, and his aesthetic has become the standard of the industry. Today, people want to know what Tiffany would have done, so with a promise to employ all the objectivity I can muster, and a disclaimer to the effect that I realize someone else may also have an opinion of what is 'right', I will wade on in.

Brass, Bronze or White Metal? Know what you¹re paying for.
The cost of a lampbase is largely determined by the type of metal from which it's made. Today, as in Tiffany's time, most lampbases on the market are made of either white metal or brass.
White metal bases are less expensive because the cost and properties of the metal (actually an alloy consisting mostly of zinc) lend themselves to the production of light-weight, low cost castings that require very little handwork. White metal bases are usually covered with a brass plating to hide their unattractive gray color and give them a more expensive look. The major drawback to white metal, aside from its light weight, is its tendency to become brittle and break with age. Heirlooms are not made of white metal.
Brass, on the other hand, is the traditional metal used in quality interior decorations and furnishings. Brass castings are heavier and usually require a good deal more handwork than zinc castings. Some manufacturers tout their bases as being made of bronze to portray an image of quality, but this is more a marketing ploy than reality. By definition, brass is an alloy of copper and zinc, while bronze is an alloy of copper and tin. Tin is a very expensive metal, which was used historically only in situations where its weather-resistant qualities warranted the expense. Michelangelo's work was often cast in bronze, but Tiffany used only brass to make his lampbases. Today, tin is rarely used in copper alloys, having been displaced by less expensive, high-tech compositions. The American Society of Brass and Copper does not even make a distinction between brass and bronze.

Brass also can vary in quality, depending on its copper content. Tiffany used a high-copper brass (80% copper, 20% zinc) - called 'red brass' - because of its workability, durability and ease of patination. Today, almost no one uses red brass, preferring the less expensive 65% copper alloy called 'yellow brass'. Some manufacturers save money by further reducing the copper content in their brass to under 50%. If the brass has a distinctly whitish appearance, it is probably what is known in the industry as Œjunk brass¹. The yellower the brass, the better its quality.

Patination - the Finishing Touch
Because most people associate Tiffany with his famous green-brown patina, it is surprising to learn that he offered his lampbases in five other finishes: gold, silver, pewter, matte brass, and 'old copper'. Some of these finishes could be further enhanced by a splatter-pattern etching treatment called 'doré'. This wide variety of finishes shows that Victorian tastes were no less varied than ours.
While gold, silver and pewter are a little exotic for today¹s market, brass and copper finishes are still in vogue. As mentioned, white metal bases are usually plated with brass to improve their appearance. Both plated white metal and brass bases are frequently given an 'antique brass' finish by dipping them in a proprietary selenium darkener, polishing out the highlights, and adding a coat of lacquer to preserve their appearance. This process gives the brass an aged appearance at a reasonable cost. Some manufacturers also offer their bases in a polished brass, copper or 'silvertone' finish. Such finishes involve plating and polishing operations, followed by a lacquer coating to prevent tarnishing. All are relatively inexpensive.
Patina finishes require more work. The Tiffany patina was accomplished by first copper plating the entire lampbase (or shade) to achieve a chemically reactive, uniform surface. The copper surface was then treated with a solution of acid salts to corrode the metal, producing a green-brown encrustation. The resultant patina was sealed with an organic coating and finally waxed. This entire process was designed to reproduce the effects found on a number of classic bronzes that were unearthed in the late 19th century - a look very popular in Victorian times. Ironically, old classical bronzes were originally 'poly-chromed' or painted, and their patina resulted only from centuries-long exposure to the elements. This didn't bother Victorians. They associated the patina they saw on the bronzes with classical aesthetics, and they simply wanted to emulate them. Tiffany was obliging, and it became his most popular finish.
Today, authentic patina finishes are rarely used on lampbases. The patination process is difficult to control, often requiring many successive applications to achieve a desirable color. Factors such as heat, humidity and light play a significant role in determining the outcome, which is often not pleasing. This unpredictability, coupled with the time and expense involved, make patinated finishes unattractice to most manufacturers.

Scale - What is Right?
This is perhaps the most difficult subject to address. What looks right is ultimately a matter of taste. If you like it, do it. On the other hand, if you aren¹t sure, I will try to provide a few guidelines that may help.
Rule 1. The diameter of the platform of the lampbase should be at least one-half the diameter of the shade. This is important for stability. It was the formula Tiffany used, and it seems to work. If the platform is smaller than this, the whole lamp becomes a little top-heavy and prone to upset. I would regard this rule as sacred.
Rule 2. The height of the lamp, excluding finial, should be about 1 1/4 times the diameter of the shade. This seems to be the most pleasant proportion for the common case of a hemispherical shade on a thin-stemmed base.
The exceptions, however, are quite diverse. Whenever the apparent proportions of a shade or base differ from the norm, the scale will be affected. To say it another way, a 25" Lotus and a 25" Hydrangea have very different proportions, although their diameter is the same. The depth of the Hydrangea requires a base that is taller than the 31" norm, while the Lotus looks best on a shorter base, because it is so shallow.
A massive lampbase, such as the Cattail and Lilypad, is comfortable at its lower height with a 20" cone - such as the 20" Dragonfly. Smaller diameter and deeper shades, such as the 18" Grape and 18" Wisteria, are designed to sit on taller bases.
Coordinating the design of the base with that of the shade should also be mentioned. Although it is not usually possible to find a base that closely matches the design of the shade, one should select a theme that is at least compatible.
A geometric shade looks best on a base with simple lines, while it might look out of place on one with a lot of busy Victorian decoration. On the other hand, a more complex shade,
such as Worden's Rococo or Classic designs, would match well with an ornate base. In the case of the 20" Dragonfly, the 'swampy' theme of the Cattail and Lilypad base brings dragonflies to mind very easily.
Support and Illumination - the Hidden Qualities
The requirements to properly display a leaded glass shade are quite different than those of modern cloth lamp shades. Leaded glass is both heavy and fragile - a combination that demands a strong structure to hold the shade firmly in place. Stained glass also typically transmits less light than fabric, due both to the opacity of the glass and the wide-spread use of darker colors. This means you are going to need more wattage to adequately illuminate the shade. Higher wattage bulbs (100 or greater) are troublesome because they don't last as long and produce 'hot spots' in the shade, especially where more transparent glasses are used. The solution is to spread the light out by using a cluster of sockets rather than just one. An analysis of Tiffany lampbases yields the following approximate formula that he used:
No. of Sockets Shade Diameter
1 10" - 12"
2 12" - 14"
3 14" - 20"
4 20" - 22"
6 22" and larger
Bear in mind that this is only a general formula. Different shades of the same diameter may vary in their lighting requirements. Light colored or translucent glasses need the least illumination, while dark colored and opalescent glasses require the greatest.
It is sometimes helpful to make a test to determine which wattage looks best in a lampshade before actually choosing a lampbase. To accomplish this, you will need a multi-socketed light source and a wide range of different wattage light bulbs. Place your lampshade where you ultimately plan to display it and try different wattage combinations until you find the one that is the most pleasing under optimum conditions. Then add up the different wattages to give you your total illumination requirements. Since 75 watts is ideally the largest bulb you should use, divide the total by 75 to get the minimum number of sockets needed. An excess of sockets is fine if the size of the shade permits it. The more light that is dispersed, the better your lampshade will look.
When using multiple sockets in the light spaces of small shades (16" or less), check to see that the lightbulbs aren¹t too close to the glass or protrude below the lower edge of the shade. As a rule of thumb, they should not be closer than 1" from the glass surface, nor less than 1/2" above the lower edge of the shade. Sometimes it is necessary to find smaller diameter bulbs to fill the requirements. Such bulbs are commonly called 'appliance' or 'fan light' bulbs.
Stability is especially important in these cramped space situations. Antique leaded glass lampbases had very stable support structures in order to keep the lampshade away from the lightbulbs. Tiffany and Handel, for example, used a sturdy central post (from which the light sockets emanated) surmounted by a large ring or wheel on which the shade rested. This kept the shade firmly in place and centered it over the lighting cluster. Modern commercial lighting arrangements, on the other hand, usually include only one or two sockets, and are designed to support lightweight materials such as cloth. Lampbase manufacturers are faced with the choice of using these less-than-adequate commercial parts or designing their own. Custom made support structures often cost more than the consumer is willing to pay. As a result, inexpensive lampbases commonly employ commercial lamp parts, such as harps or sheet metal clusters, to keep the cost of their product down.
Sturdier support structures are usually found only on the more expensive brass lampbases, most commonly copies of antique designs. In addition to multiple light clusters, these bases typically use a wheel/ring/cap arrangement to secure the shade.
The wheel provides broad support for the shade, so it cannot tilt to one side and come into contact with the lightbulbs. A heavy brass ring is soldered into the top of the shade, and a ventilated heat cap holds it down on the wheel. These heat caps are made of thin sheet brass to provide a stress release point in case of an accident. If the lamp is tipped over, the cap will bend and the mounting screw will strip out, freeing the shade and minimizing impact damage.
The modern alternative to cap and wheel arrangements has been commercially available vase caps which are soldered into the top of the shade. Vase caps are secured to the base only in the center and pretty much rely on the even weight distribution of the shade to balance itself and remain level. Improvements were made with the introduction of perforated vase caps and 'solder-on' Tiffany-type caps that allow for more adequate ventilation than the commercial ones. While not as stable as wheel arrangements, these 'solder-on' shade mounts will always be popular, because they are inexpensive.
In the final analysis, choosing the right lampbase is frequently a matter of price more than anything else. Good quality lampbases for leaded glass are available if the customer is willing to pay for them. If price is a consideration, then some of the less expensive choices are certainly adequate. Not everyone is looking for a lampbase to complement an heirloom. But for those who are, a knowledge of what is 'right' is invaluable in making the decision.

Paul Crist, owner of Odyssey Lamp Systems, is an acknowledged authority on Tiffany lamps. He is often called upon to authenticate lamps in collections as being the product of Tiffany Studios.

Professional Stained Glass  1986