In recent discussions with Henry Halem, I brought up the problem of surface devitrification. Perhaps this is a reason to go to pyrex. Perhaps the aluminizaing and overcoating prevents devitrification. There is a lot we don't know about this! I have told Henry that I would pass some of his writings on to the ATM community. For those ATM's with kilns, I highly recommend Henry's book, GLASS NOTES. A new revised edition is presently being prepared, so you best contact Henry to find out when it will be available. Henry Halem wrote: > >On the surface devitrification, you may not know that it actually can > >happen at room > >temperature. > > Richard, > Yes I knew it can happen at room temperature. When one tests a glass for > durability it is to see how chemically durable it is at room temperature. > Glass that is exposed to moisture and especially alkalai/acid enviroments > will, if not formulated to be chemically durable will eventually devitrify > and if the formulas are really out of whack will devitrify in your living > room. Window glass is not all that durable but you usually clean the glass > with an Ammonia based cleaner which removes any slight devit when you clean > it. One must test any glass for chemical durability. Read the chapter on > Durability. If your going to get in this glass game you are going to need > some sophisticated equipment but I bet you knew that. > Henry > > --------------------------------- > Franklin Mills Press > P.O. Box 906 > Kent, OH 44240 > tel. 330/673-8632 > fax 330/677-2488 > http://www.glassnotes.com > email hhalem@glassnotes.com
-- BEGIN included message
- To: Richard Schwartz <richas@idt.net>
- Subject: Re: Durability
- From: Henry Halem <hhalem@glassnotes.com>
- Date: Sat, 26 Dec 1998 23:14:50 -0500
- In-Reply-To: <368594BF.57C65B6E@idt.net>
- References: <36743B83.F9FB1647@idt.net> <367546F2.D8477D76@pop.raex.com> <l03110700b29bf4a2975f@[204.42.56.37]> <l03110702b29c5dfe69e2@[204.42.56.14]> <l03110704b2a6dd1424c7@[204.42.56.14]><l03110701b2a9d55f7f46@[204.42.56.245]>
>On the surface devitrification, you may not know that it actually can >happen at room >temperature. Richard, Yes I knew it can happen at room temperature. When one tests a glass for durability it is to see how chemically durable it is at room temperature. Glass that is exposed to moisture and especially alkalai/acid enviroments will, if not formulated to be chemically durable will eventually devitrify and if the formulas are really out of whack will devitrify in your living room. Window glass is not all that durable but you usually clean the glass with an Ammonia based cleaner which removes any slight devit when you clean it. One must test any glass for chemical durability. Read the chapter on Durability. If your going to get in this glass game you are going to need some sophisticated equipment but I bet you knew that. Henry --------------------------------- Franklin Mills Press P.O. Box 906 Kent, OH 44240 tel. 330/673-8632 fax 330/677-2488 http://www.glassnotes.com email hhalem@glassnotes.com
-- END included message