We're all familiar with colored glass, from gorgeous stained glass, to colored vases, to glass colored red or green, blue, pink or yellow. How did our favorite glass companies in the 1930s make colored glass? This pink bowl from Fostoria is pink all the way through. Glass companies like Fostoria added mineral colorants to the molten glass to give it color. Some of the colorants seem rather exotic - uranium salts were used to make some yellow glass for example - while others were costly. Early glass makers made red glass with gold colorants, for example, but by the 1920s or 30s had discovered less expensive colorants like selenium mixtures.When people talk about "colored glass" they usually mean glass with color an intrinsic element of the glass body, like my Fostoria Versailles bowl above. You'll also find glass that is stained, which is a fairly permanent decoration using an applied color, often red like this creamer. Another technique is "flashing", which is similar to stained glass but less permanent. It can be hard to tell stained from flashed. As a general rule, the inexpensive glass from the 1970s or so, like the Indiana Teardrop piece, are flashed. You can often see a fuzzy boundary where the flashing tapers off, while stained pieces have neat boundaries, like someone colored inside the lines. Makers usually applied flash colors by spraying the pieces with colorant and that technique left some indistinct boundaries. You can see little scratches on the stained creamer. Stains are more resistant to wear, but if they get scratched the clear glass shows through. Flashed glass scratches easily. Most of the flashed pieces I've seen at estate sales has been badly scratched and looked pretty bad. Colored glass scratches too, but since the glass is colored all through, the scratches aren't as noticeable. I've seen red, cranberry, amber, yellow and green stains on older glass. Indiana made flashed pieces in Teardrop in red, green, blue, yellow, a yellow-to-red color and probably more. Flashing is less costly than producing colored glass (remember the colorants are pricey) and that may be one reason it was a common technique in the 1970s. If you are considering glass for food use, I'd recommend avoiding flashed pieces since the flashing does come off easily and is not at all dishwasher proof. Most of the stained or flashed pieces have the color on the outside, not the inside, but that might be something to note too. I will cover for other techniques like cased, goofus, and painted glass in future posts. Did you miss the posts the last two weeks? I had some unanticipated travel that took me away for several days but am back now and am back to blogging!
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