silica content in brick and mortar

[gridrunner]

I have become quite interested in building one of these ovens, and have been pricing out materials. While pricing out firebrick, I explained to him what I was doing and he warned me about the high silica content of the brick being a hazzard to cook food on, and told me that commercial refractory cement has atleast twelve different oxidants in it, and would not recemmend using any of it, and to try and find low silica bricks and special mortar. Browsing this site and the net I have found no mention of these concerns and am wondering if he is just being over cautious or whether there is some legitimacy to this?

[david s]

Re: silica content in brick and mortar

The concern with silica is the crystallization that takes place at much higher temperatures, about 1100 C I think, way higher than we fire to. It's quite safe for our application as far as I know.

[timmarhy]

Re: silica content in brick and mortar

crystiline silica is an air borne hazard
http://unionsafe.labor.net.au/hazard...876604328.html

ALL bricks and cement contain it, it's a basic component of sand etc. as far as i can see unless you plan to fire the bricks at over 1000c repeatedly and scrape off the tiny silica crystals and eat a few grams of it every day for years the worst you will get is a very painful kidney stone
Urolithiasis in a patient ingesting pure silica: a...[Scan Electron Microsc. 1986] - PubMed Result
wear a dust mask when cutting the bricks, but most importantly wear steel caps, saftey glasses, look after your back and use power tools with care while building a pizza oven - these are the real dangers of building one.