Glass Available in JUCAs


This is our standard glass. It is the same kind used in nearly all fireplace doors and in some woodstoves. It is pretty heat-resistant and VERY impact resistant. TEMPERED GLASS is the type of glass best able to pass the UL safety tests (ours did in June 1979). TEMPERED GLASS ages-it gradually loses its temper. This happens faster at higher temperatures. At a constant 500°F, about half of the temper will be lost in 80 years. At 950°F, it will age it that much in 20 seconds. The glass design temperature of most JUCAs is 370°F, well within the safe operating range.

If it ever breaks, it loudly breaks into thousands of tiny pieces (like the rear window of a car). The mesh screen would make sure no pieces come out into the room.


These exotic glasses are NOT tempered - they do not age. Actually, PYROCERAM technically isn't even glass! Both are just as clear as normal glass. Their heat-resistance is spectacular, from 1200°F to 1800°F continuous, far above any temperature they could be subjected to in a woodburner. If a JUCA is used hard, as the smaller JUCAs, such as K-3s, B-3Ns and B-3JNs, sometimes are, the optional glass might be a good choice. (Some small firebox JUCAs include this "optional" glass as standard). (VYCOR was in the APOLLO spacecraft windows.)

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