My experience parallels Mike's, glazed masonry failures are usually attributable to more complex problems than simply freeze thaw. Failures are usually a combination of a few of the following: structural frame movement (sway, concrete creep, etc), thermal expansion, corrosion of imbedded steel supports and/or anchors, poor glaze/bisque adhesion, etc. However, I had reason to review ASTM compliant test data from a previous repair project on a tall building with a shiny top here in NYC that the owner had hoped to use the stockpile of remaining glazed bricks. The data indicated that the bricks were fine for compression, efflorescence, glaze performance and a few others that do not readily come to mind. However, they did not pass the absorption coefficient (the % weight difference between cold water and boiling water saturation). This is supposed to indicate the brick's ability to be saturated but still have enough pore space to allow the freezing water to expand in to. So we rejected the brick. The brick from that previous program that had been installed on the building had visibly failed (cracks and spalling) so we replaced it. It is my opinion (we did not test "why" the bricks actually failed) that it was a combination of poor brick PLUS other faulty practices such as portland cement rich mortar, unintentional mortar cavities behind the brick and poor expansion joint construction. However, the freeze thaw performance was probably the primary reasons. Eric Hammarberg Director of Preservation Sr. Associate LZA Technology 641 Avenue of the Americas New York, NY 10011-2014 Telephone: 917.661.8160 (Direct) Mobile: 917.439.3537 Fax: 917.661.8161 (Direct) email: [log in to unmask] -----Original Message----- From: edison [mailto:[log in to unmask]] Sent: Wednesday, July 09, 2003 6:51 PM To: [log in to unmask] Subject: Re: brick soaking Wow, preservation content! Having worked on hundreds of terra cotta buildings in every kind of climate, I have become convinced that freeze-thaw has little to do with typical glazed brick or terra cotta damages. The same things happen to terra cotta in San Francisco, Florida and Hawaii where it never freezes, as in New York or Cleveland or Boston with lots of freeze-thaw cycles, or in Northern Minnesota or Alberta which is just plain freeze all winter with no thaw. Nevertheless, my understanding of freeze-thaw testing is that it takes multiple cycles to get results, and that freezing is done under saturated conditions. Results can be sketchy and hard to reproduce, I am told. I have seen data for 60-200 cycles of testing presented to provide comparisons between different materials. As for getting things saturated, we would normally start by oven-drying the piece to establish what "dry" is, which involves leaving it in there and weighing it periodically until the weight doesn't go down any more. Then immerse the thing in water and keep weighing it periodically until the weight doesn't go up any more. Some pieces may take weeks to become saturated. Some are soaked in an hour. Edison Coatings, Inc. M. P. Edison President 3 Northwest Drive Plainville, CT 06062 Phone: (860) 747-2220 or (800)697-8055 Fax: (860)747-2280 or (800) 697-8044 Internet: www.edisoncoatings.com E-Mail: [log in to unmask] ---------- Original Message ----------- From: Met History <[log in to unmask]> To: [log in to unmask] Sent: Wed, 9 Jul 2003 15:29:05 EDT Subject: brick soaking > I have a fragment of a white glazed brick. I am soaking it in water, > and ultimately want to freeze it to see if the absorbed water will > fracture the brick. > > 1. I don't notice any bubbles coming up. Does brick not > absorb water in this fashion? > 2. How long should I wait? > 3. Once the water is absorbed, will freezing actually produce > the desired results? Or should I just use a hammer? > > Christopher ------- End of Original Message ------- -- To terminate puerile preservation prattling among pals and the uncoffee-ed, or to change your settings, go to: <http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> The information in this email and any attachments may contain confidential information that is intended solely for the attention and use of the named addressee(s). This message or any part thereof must not be disclosed, copied, distributed or retained by any person without authorization from the addressee. If you are not the intended addressee, please notify the sender immediately, and delete this message. <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> -- To terminate puerile preservation prattling among pals and the uncoffee-ed, or to change your settings, go to: <http://maelstrom.stjohns.edu/archives/bullamanka-pinheads.html>