Hank Murrow on tue 5 dec 00
>Cameron wrote in part;
>Higher density fiber has better thermal resistance than lower
>density fiber, hence a more compact fiber is a better insulator.
>Fiber blanket is usually 8 or 10 pounds per cubic foot density,
>formed fiber, such as boards can be much higher, such as 18 or 24
>pounds per cubic foot.
****Hank reports;
That in his experience, folded blanket modules perform best at 12-15# per
cubic foot density. Over 20# per cubic foot density will reduce the
insulating efficiency of ceramic fiber blanket.
>Radiation passing through air at higher temperatures transfers
>more heat than the fiber at the same, elevated temperatures.
****In fact, most of the heat is radiated back into the kiln by the
thermally reflective fiber hot face at temperatures above C/1. Think of the
fiber kiln as a house of mirrors.
>You cannot hurt the fibers by compressing them. There are two
>reasons for this, firstly, the ceramic fibers are extremely
>strong, a phenomenum of very thin fibrous materials. Secondly,
>they are relatively short and flexible and are not too prone to
>breakage anyway.
****This is quite true of unfired fiber. However, fired fiber loses
most of its elasticity once taken above red heat. Often the fiber near the
cold face remains flexible; but it would not be desirable to 'compress the
hot face of a fiber kiln which had been fired once.
Thanks for your response, Hank in Eugene
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