Pyrex Opal Ware Decoration
Corning used a variety of methods to apply decorative patterns to its Pyrex opal ware products, from 1955's Desert Dawn through 1983-1986's Homestead.
Screen printing was the most often used method of Pyrex opal ware decoration. Much like any other screen printing process, the dish or bowl was maneuvered into contact with the screen in a manner appropriate for its shape and size. The mechanism would then apply the paint through the screen, before the piece moved along the line for the decoration to be fired on.
Since screen printing necessitated mechanical handling of the dish or bowl, allowances had to be made for the different shapes. The decoration typically could not extend all the way around the piece. Protruding handles interfered with the application in many cases, necessitating gaps, and are also the reason why the pattern is positioned noticeably lower on some dishes than might otherwise be expected.
A two color pattern meant the screen process had to be done twice to each piece, one pass for each color. Friendship and Town & Country standard version are the prime examples. Although the process normally resulted in the colors being "in register", slightly skewed examples are sometimes seen.
More intricate decorations were often beyond the scope of screen printing, and necessitated the creation and application of decals instead. Decals used in US Pyrex production were typically monochromatic, but those seen in UK, Australian, or New Zealand production were more often multi-color, some to the point of near photo-realism.
Gold decoration was meant to lend an upscale air. Its use was primarily on promotional pieces, but it is also seen on Limited patterns Golden Acorn and Golden Honeysuckle, and the Standard pattern Early American.
Gold decoration was normally applied to painted surfaces, apparently not adhering well to plain opal glass. Nevertheless, gold decoration was applied directly to clear glass lids of various promotionals, where it is often seen worn or damaged.
The use of gold decoration was discontinued around 1970, coincidental with new popularity of microwave ovens, with which the metallic gold paint was incompatible.
The scratch process or technique was an ambitious one. Instead of simply applying multiple applications of different colors of paint, the process involved applying a second coat of a different color over an already-fired on coat. A patented machine was then used to rotate the bowl and at the same time remove narrow bands of the overcoated color, letting the base color show through. The result was meant to mimic the look of hand-thrown terra cotta earthenware, and was limited to a single, short-lived pattern called, appropriately, Terra. Because the technique required the subject pieces to be round, the pattern was limited to open stock round bowls and Cinderella round casseroles, as well as sets of handleless mugs, plates, and small bowls. Terra was soon discontinued, apparently due to its more expensive production cost.
In all probability, the Rainbow Stripe bowls were also produced using the scratch process tooling, the difference being there was no base coat, and the bands of color removed were uniformly spaced rather than the pseudo-random effect of Terra.
Overspray was used on a handful of patterns. After a piece was given an overall fired-on coating, another sprayed-on decorative application followed.
On FlameGlo and Old Orchard, it consisted of a second color being applied to the top half of the bowl in a fade or "ombre" style gradient. It appears the technique was confined to round shapes, as it is absent from the Old Orchard ovals.
On Desert Dawn and Homestead, the overspray was a uniform spatter, giving the pieces a speckled appearance. Desert Dawn was meant to look like sand. In the case of Homestead, the intent was to evoke a look reminiscent of crockery. Forest Fancies also used a speckled overspray.
Creative examples include the lids of the "Floral Bubbles" and "Spirograph" promos, whose lids had different elements of the decoration printed on both their tops and undersides. This technique was meant to give a sense of depth to the design.
It is curious that another resource has long held that independent sources verify the Floral Bubbles lid is in fact printed only on one side, but, under close inspection, it is clearly not. While the black pattern on the top is screen-printed, the brown pattern on the underside is a transparent tint.
Americana/Earthtones and Multitone Blue 400 series bowl sets were unique in that, while painted in solid colors, the rims were left bare opal white.