Blenko Museum

The 8 Basic Characteristics of Blenko

Blown	Pontil	Thickness	Rims	Cold Work	Color	Transparency	Numbers

Following is a simplified guide to regognizing and identifying Blenko glass.
Please bear in mind that there are exceptions to every rule; the making of Blenko glass was an art rather than a science.

Blown

click on images to enlarge

Blenko glass is hand made and hand blown; as such it often displays characteristics unique to that method of production; chords, bubbles, tooling marks, etc. Only cast items are not blown, this accounts for less than around 5% of Blenko's overall production, primarily bowls, usually thick, and mostly inconsequential items.

pontil on a polished base with sand-blasted signature visible

pontil on Amethyst 5427S

pontil on Plum 6717

pontil on 517L

fire polished rim still showing evidence of shearing or tooling marks

smooth and even fire-polished rim

#964L horn vase with detail showing cold-worked polished and beveled edge

bevel polished rim on a 1959 design

ground stopper stem and decanter neck

example of fully ground stopper stem, bottom also ground

example of ground surface on interior of decanter neck where stopper fits

Pontil Marks

A pontil rod (sometimes called a "puntee" or "punty") is the solid metal rod that is attached to the base of the still molten item so that it may be "finished" (also called "tooled" or shaped) after it has been blown and broken off of the blowpipe. When the item is removed from the pontil rod, a circular mark is left behind, this is called a "pontil mark."

The majority of Blenko glass (and much other blown glass) has pontil marks on the base, which is only occasionally polished. There are a notable number of exceptions to this; not all Blenko designs will have a pontil, ex: #7220. Cast items do not have pontils. See example images of pontils to the right, click to enlarge.

Thickness

Typically, the walls of Blenko vessels are thicker than most; Blenko is rarely lightweight or thin walled. There is no easy way to quantify this though it is certainly not unusual to see rims that are 1/4" thick or slightly more. See rim images at right.

Rims

The vast majority of Blenko's rims are fire-polished, meaning rounded and sometimes slightly uneven, an effect produced by briefly reinserting the item into the furnace to eliminate shearing and tooling marks after it has been shaped. See example images at right (click to enlarge). It is unusual for Blenko rims to be polished/ground, see next note below.

Cold Work

Only rarely is Blenko ever cold-worked, meaning polished or cut, particularly on the rims - though 1959 designs in particular contain many exceptions to this rule and the 964 horn vase is another noteworthy exception. See example images at right (click to enlarge).

The underside of Blenko items are only ground if it is required to make them sit level, and again this is the minority of items. Blenko did not polish bases with the sole intent to remove pontil marks; these were proudly left as evidence of being handmade.

Most Blenko decanter stoppers however are, in a fashion, cold worked; they are ground to fit. Both the stopper stem is ground as well as the interior neck of the bottle where the stopper sits. This is done to create a proper fit and seal. The grind is not polished so it retains a rough "frosted" look. See examples at right, click to enlarge

Color

Blenko's defining characteristic, and the simplest (but by no means surest) way to identify it is by the color. For detailed information on this characteristic please see our Color page which includes comparative examples and a complete list of colors used, grouped by color range.

Transparency

Historic Period Blenko (1947-74) is always transparent, never opaque or transluscent. There is one exception to this: Rialto, designed to have a transluscent white body with contrasting ruby elements, made only in 1961. It is worth noting that on very rare occasions Tangerine and Jonquil, circa 1959, struck as somewhat opalescent or with opaque areas, allthough this was not by design and was random.

In the Late Period there are a few more instances of non-transparent glass, but again it is the vast minority.

Design Numbers

All authentic Blenko is associated with a unique design number (or, in rare instances, an equivalent designation). To authenticate an item as Blenko one must be able to match the shape and size to a corresponding design number. For detailed information on this, see our Numbers page. If a design is undocumented, its authenticity is highly questionable regardless of guesses, provenance and attribution.

A note on "experimental" items: Beware! Each year Blenko produced new designs to add to the line, a small number of items, about 6-12, were rejected each year for a variety of reasons (cost or difficulty to produce, design flaws, marketability, aesthetic shortcomings, etc). Commonly 2 prototypes, only occasionally more, were made of these rejected designs and then sold in the Visitors Center (or its pre-cursor) along with seconds.

Most items called "experimental" Blenko are almost always just another company's product that the seller can not identify (example: p. 83 of Pina's "Blenko Cool", first ed., identifies a Zeller vase as "experimental Husted."). Such items are best avoided unless accompanied by convincing documentation. Please see our Fakes & Similar page for more information on this.

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