Opalescent Carnival Glass - The Fire Within
Pictures are courtesy of G&S Thistlewood unless otherwise stated
|
September 2020
|
Imagine a misty morning … as the sun begins to rise you see a glimpse of gold and fuchsia sunlight shimmering in the aqua blue sky. The colours of aqua opalescent Carnival Glass are a perfect memory of such a morning.
Opalescent glass that was also iridised – opalescent Carnival – is known in the form of aqua opal, peach opal, vaseline opal and more. What exactly is opalescent glass, how was it made and which glass companies produced it? Let’s find out. The familiar name Lalique is often associated with beautiful examples of opalescent glass (but note that their glass was not iridised). Opalescent glass techniques used by Lalique were not uncommon, and were used by other glassmakers. Lalique Birds bowl on the left and a Jobling Birds bowl on the right.
Both are super examples of opalescent glass, dating from c. 1930s. The Jobling piece is felt to have been inspired by the Lalique one. |
Northwood Hearts and Flowers comport in aqua opal
|
What is opalescent glass?
Opalescent glass has a distinctive pearly white edge, and often also has that same pearly whiteness on the thicker parts of the glass (the high points of the pattern) which enhances the design. The rest of the glass can be clear or other colours (determined by the colour of the “base” glass itself). The effect of opalescence is likened to the opal gemstone, which possesses a kind of reflective, sometimes colour-changing light. Opalescence on glass may also exhibit an inner glow, often called the “fire”, when light shines through it.
It’s important to note that glass that is white all over (not just on the edge or high points) is known as “milk glass” and was made using different ingredients and a different process. See footnote *
How is opalescent glass made? The secret to achieving the opalescent effect is a combination of ingredients that are added to the glass mix (the "batch") and the skilled techniques used in the glassmaking process. Let's roll the clock back 131 years and look at the explanation given by Thomas Davidson, the renowned English glassmaker. In December, 1889, Davidson & Co. took out a patent (#2641) for their opalescent glass which they called “Pearline”. Davidson's explanation of the appearance of his opalescent glass and its production process, is exceptionally clear, revealing and informative: “According to my invention I manufacture articles such for example as ornamental dishes, vases, jugs, tumblers, and the like of pressed glass in such a manner that at the base they are composed of clear glass or glass of any transparent color whilst towards the top they gradually become milky and at their upper edge opaque.” Davidson went on to describe the process of creating opalescent glass in the clearest and most easily understood way we have come across. After mixing the ingredients and heating up the glass batch, Davidson explained that: “the glass is then moulded in the usual way for making pressed glass. The moulded article which at this stage is transparent I allow to cool for a short time and then expose it on a punty or rod in a strong heat, it then assumes the effect described; the parts most heated being most opaque, and the parts not heated so much remaining clear which is regulated by the workmen according to the length of time the article is kept in the flame.” |
Cover of Davidson’s catalogue c. late 1800s
|
The crucial ingredient that Davidson added to the glass batch to make opalescent glass was bone ash, also referred to as calcium phosphate or phosphate of lime. Ingredients such as cryolite, could also be used in the batch to produce opalescence, and others such as arsenic, could be added to enhance the opalescent effect. The critical step in the glassmaking process - the cooling and subsequent reheating (in the "glory hole") - is a process referred to as "striking", and is essential to coax out the opalescent effect. It only occurs within a limited range of temperatures. On the right is a piece of Davidson’s Primrose Pearline (vaseline) glass – note how the opalescence picks out the pattern on all the thicker parts of the glass, as well as the top edge. The English Registration number of this boat-shaped piece is RD. 212684, and the pattern was given the name War of the Roses by Heacock (Davidson did not give these pieces pattern names). |
Davidson's Primrose Pearline. The base glass is vaseline
|
Can a piece be both opalescent and iridescent?
Yes indeed – that is Opalescent Carnival Glass. After heating in the glory hole to coax out the opalescent effects (to "strike"), the glass would then be removed and sprayed with the “dope” (the metallic salts that produce the iridescence) while still very hot.
The opalescent effect on Carnival can vary from a delicate and fine hint of opalescence (as seen on some of the Fenton examples) to a denser, broader effect (as seen on most Dugan-Diamond examples). These contrasts were probably caused by the different methods of re-heating employed by the various Carnival manufacturers and/or individual glassmakers, or by adding varying amounts of bone ash to the glass batch. When the opalescent effect occurs on clear glass with marigold iridescence it is known as peach opal; when it occurs on light blue-green glass it is known as aqua opal. These are the two main examples of opalescent finishes, but there are other rarer opalescent colours such as amethyst opal.
Yes indeed – that is Opalescent Carnival Glass. After heating in the glory hole to coax out the opalescent effects (to "strike"), the glass would then be removed and sprayed with the “dope” (the metallic salts that produce the iridescence) while still very hot.
The opalescent effect on Carnival can vary from a delicate and fine hint of opalescence (as seen on some of the Fenton examples) to a denser, broader effect (as seen on most Dugan-Diamond examples). These contrasts were probably caused by the different methods of re-heating employed by the various Carnival manufacturers and/or individual glassmakers, or by adding varying amounts of bone ash to the glass batch. When the opalescent effect occurs on clear glass with marigold iridescence it is known as peach opal; when it occurs on light blue-green glass it is known as aqua opal. These are the two main examples of opalescent finishes, but there are other rarer opalescent colours such as amethyst opal.
Above: the magnificent iridescence on the face of this Dugan-Diamond Garden Path Variant chop plate stops the intensity of the opalescence showing through, but what a surprise you get when the plate is turned over and viewed from the exterior. The opalescence covers almost the entire plate – startling and very beautiful. This colour is known as peach opal – that is marigold iridescence on clear base glass, with opalescence. Thanks to Greg Dilian for these two photos of this amazing plate.
|
Shown below are two peach opal vases with very contrasting, and very striking opalescent effects. On the left is a short Lined Lattice vase that was made by Dugan-Diamond with an opalescent effect that looks like snowy mountains. The opalescence comes through not only at the top of the vase, but also on the thicker sections of the pattern.
On the right is a Westmoreland Corinth vase with a Jack-in-the-Pulpit shaped top; again we can see that the thicker sections of the glass – in this case, the vertical ribs – show stronger opalescence.
|
|
Above: Estate sugar and creamer, peach opal, Westmoreland (Seeck Auctions).
|
Above: Westmoreland also made this very beautiful blue opal
Fruit Salad punch bowl and base. It is a rare item. (Seeck Auctions). Left: a display of four Fenton opalescent Carnival bowls. They are, clockwise from top left: Dragon and Lotus, aqua opal; Dragon and Lotus, vaseline opal; Peacock and Grape, vaseline opal; Dragon and Lotus, peach opal. |
* Footnote: there are other types of pressed glass that can be mistaken for – but are not – opalescent, including milk glass and moonstone, and there is information about such treatments on our website: Carnival Glass Colours - Opaque and Semi-opaque