CHOOSING THE RIGHT LAMP BASE
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
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
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
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
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