Do I have the right bricks?

[Dolf]

Hi
I am a newby but have been lurking the forum for a while and have studies the plans (thanks for posting for free!). Thanks to all for sharing your knowledge so graciously.
If I may also pose a question please? My concern is if I have the right bricks. I got a stack for free. 220x110x60. They came out of a Pilkingtons glass cooling area when the plant was refurbished in 1978. So these bricks bave been lying in the back of the garden for years hence the old/soil look on some. As you can see they have ECLIPSE and VR writen on them. They weigh 3.7kg each but when submerged they hardly pick up any weight. They are also difficult to cut. I add a pic to show colour and ?texture?.
I have no previous Pizza making experience but ample Pizza eating experience  I plan a 42? for personal use over weekends since the place where I want to build it is only a weekend hide-away.
So Question 1 is if I can use them (hope you say yes!)
Question 2 deals with the square brick also in a pic with a VR3 rating. These were used in another area of the plant but the guy who gave them to me cant remember where. I have just enough of them to make a floor if you guys ok them and since they are bigger they may well give a smoother floor given the chipped corners of the old bricks. They weigh the same proportionately
Any advice would be great please.
Thanks
Dolf

[andreas]

Re: Do I have the right bricks?

hey there mate if they were from 78 and pre im sure they fall into the old brick solid type, give one a whack with the sledge hammer if it smashes to bits then no good if it just splits in solid pieces then good, im sure they will withstand oven temps it comes down too how long they hold the temp, but im no expert just learning....

[Dolf]

Re: Do I have the right bricks?

Thanks for the advice. I have no clue if "old style solid brick" is good or bad so I have tried my best to find answers to your questions: The first 3 pics show the sledgehammer test (x3) All the pieces did not stay together as they are on the photo. They scatered to about 1m away, but I gathered them to show shape. The one where there are less pieces is the first one. The next two I used more force.
It seemed to be ok as per my interpretation of your advice, so next I had to answer the ?heat holding quality? issue. Appologies to the research Proffessors out there, I gues you will cringe at my abuse of your acurate science but I think it may show something. I took one of the crash test pieces and chipped a way a bit more to equal exactly 1Kg. Next I placed it in the house electric over and heated it to what the manufacturer claims must be 200C, so I guess accurate within 50deg I then poured exactly 1litre of cold water on top of it. (room & initial water temp 27C. Exactly half of the brick inside the water.) The expected original sizzle and then the water temp started to rise, settling after 6 minutes on 41C. From there the decline was measured and graphed.
To have a comparison I boiled water and threw 1 litre into the same container (this time no brick). I measured the cooling similar to the previous one. Excell then helped me to draw the graph in the pic attached. To me as non scientist it seems the brick doubled the heat retention of the water.
Now the question to all you friendly and clever people out there. Is this heat holding capacity any good? I know the temp range my ?lab? could muster is very low indeed, but maybe it helps in some way?

[andreas]

Re: Do I have the right bricks?

Dolf from how i understand the advice i have been given i dont think your bricks will do, i have been told that if they break into many pieces then the density of the brick is not good for the extreme heats of an aoven if the brick breaks solid and clean just one break then it may be ok, now from another view that i have also been told bricks when made are fired at about 700 deg plus anyway so your test would not be conclusive because it can withstand that heat produced in a home oven, maybe light a fire in the back yard with wood and heat it up or buy some fire bricks, im assuming your in geelong (pilkingtons factory there ) ? there is john the oven man and a place in sunshine that sell them search refractory materials.... or on the cheaper side look in ebay for a deal

[david s]

Re: Do I have the right bricks?

Your bricks look to me like pressed red brick. They are not as refractory as fire bricks, but many members have built quite successful ovens from them. Give it a go, especially if you got them free, you haven't got much to lose.

[nissanneill]

Re: Do I have the right bricks?

Dolf
your pictures really do tell the true story.
Fire bricks vary immensely throughout the world and even in local areas.
Your sledge hammer test is fine, as expected the bricks simply broke into pieces and didn't crumble into a mess of small particles.
The fact that they were used in a Pilkington's process, they don't do things by halves. The weights are also around the mark rather than an insulating brick.
Go for it, your build will be fine, I would have no hesitations in using them for another build.

andreas,
don't be dismayed by the bricks breaking into several pieces. This should happen when hit with a sledge hammer. If it was only an engineers ball pein hammer, then it might only break into two pieces. If a brick is soft, it will break into many pieces and crumble into fine bits and some dust. These are the ones that need to be avoided.

Neill

[andreas]

Re: Do I have the right bricks?

Thanks neill

[Dolf]

Re: Do I have the right bricks?

Thank you very much gents for your advice. Andreas I am in South Africa. I have found a place which sells the refractory mortar and the fire clay and they have fire bricks as well. But at a charge of a converted $4 a piece they are way beyond my budget.
What I was afraid of (being from a glass factory), that they might have been the high heat type folks warn about. Especially the alomost no absorbsion (let alone 20%) was the clincher to get me in a spook. Thanks to the good advice gained and the 3.7 kg, I will proceed. I wiil keep a record and post later, but do not expect results too soon, I do not get a chance to build all that often. At this stage only the foundation is cast

Thanks again! :-)