rmh brick question

I am looking at getting bricks for the six inch system of ernie and erica's and was wondering if these bricks would work or not. http://www.lowes.com/ProductDisplay?partNumber=149492-22076-024300200&langId=-1&storeId=10151&productId=4514218&catalogId=10051&cmRelshp=rel&rel=nofollow&cId=PDIO1 (its a link to lowes)
If they do work then they are like 2 cents a brick cheaper then buying used bricks in my area. Thanks

No! do not accept anything that they are not advertising as fire brick , A 9'' X 4.5'' X 2.5 fire brick should weight between 28 and 30 ounces, accept nothing less, though Lowes
should have them, and a 9'' X 4.5'' X 1.25 , called a split !

Failing to get ether of those -I would fall back on old soft red -red orange bricks, unless theu have been repointed with a cement based mortar they should clean up easily if
they don't, they should be regarded with suspicion ! Hope this helps Big Al !

BUt what really is the difference. I guess now my question is why.

Nick Mason : Pardon me while I gloat a little while, answering these kind of questions from a Mason ! You asked the questions, at least four, though you probably don't think so !

You need to goto -' traditionaloven.com/articles/81/ '.. ' traditionaloven.com/articles/84/ '..' Traditionaloven.com/articles/95/ '..
and, ' Traditionaloven.com/articles/101/ ' , But please do not try any cement cladding on your Burn Tunnel/Combustion Chamber, this is 1) an advanced technique,subject to
a very high failure rate ! and 2) we can and will build better !

Have you gone to ' rocketstoves.com ' to get your PDF Copy $15 of Evans' and Jacksons' great book ' Rocket Mass Heaters ', there is STILL No other book in any language with as much
Rocket Mass Heater RMH Information ! With ~100,000 RMHs~ built world wide, most of them were built from 'The Book' and 95% of all the first time builds (that worked) were
made with "The Book" !

Please be alert and very careful about any thing that you see on You-tube land, there is a tremendous amount of crap out there, only take information for a build from someone
you KNOW and trust, or come back Here ! For the Craft ! Big AL !

So what your saying is that even though they say they are made out of clay, there is cement in them as well?

Firebrick is made with high levels of alumina and silica whereas red shale clay bricks have elevated levels of iron. The key difference is the rate of thermal transfer through the brick. Firebrick moves the heat through rapidly so the temperature on one side of the brick is close to the other side. The red shale brick does not transfer the heat well. One side will be significantly hotter than the other. Bricks expand when heated. IF the temperature is uneven, the brick will crack as one side expands more than the other. This is called thermal fracturing. It can occur with each heating or cooling cycle. You can use red clay brick but it will disintegrate. You'll be replacing it after a couple of hundred firings. The firebrick could last for decades.

Nicholas Mason : Cement cladding/coating is an add on, I am recommending that you do not travel that road, if you do you are going yourself, to little to gain,
much to lose ! Big AL ! have you read those short articles ? A. L.

I am not going down that road, I am going to trust your advice so no worries, I just like learning, and knowing the reasons why.