Identifying Fire Brick

I'm currently scrounging up materials for a small rocket stove on craigslist. Being new to the world of bricks, I don't really know what it is I'm looking at.....Is there a sure-fire (pun intended) way to tell fire brick apart from other kinds of brick? Other than subjecting them to intense heat and waiting for them to crack, I mean.....

Also, if the rocket stove is for an occasional (several times per week) cooking application, is it even necessary to use fire brick?

Thanks!

Alex; You do not have to use firebrick if you can't find any ,especially if this is an occasional use rocket stove. Regular clay brick will ultimately crack from the heat but this could take quite a while. Most firebrick you will find are the dense heavy ones ,noticeably heavier than a standard brick. Most but not all will have a name or sometimes a number cast into it. They generally are a white /yellow / color. sometimes tinted red from heat .clay brick that is old will draw a line on the sidewalk just like a piece of chalk , newer clay brick won't do that. Old clay bricks sometimes are solid and sometimes they have 3 large holes thru them to help hold them together when cementing. Fireclay is something you should be looking for while scrounging. I've included 2 photos, the bricks in the sled are all fire brick and the ones stacked by the wall are old clay bricks.

Firebricks are generally 4 1/2" x 9" x 2 1/2" or 3" (I saw some new cheap ones recently that were a bit smaller), while common bricks are generally about 4" x 8" x 2 1/2". Firebricks are commonly whitish or pale yellow, though there may be other colors. They will be very exact in dimensions and edges, though used ones may have chips and ragged edges.
You don't want any bricks that have a series of holes through them; that is an indication (not the only one) of newer hard common bricks. If you can find very old (like 80-100 years or more) red bricks that are soft enough to make a red streak like sidewalk chalk, those will work fine for your application. Hard red bricks are brittle and will not stand up to the heating/cooling cycles a rocket stove gives. Soft red bricks are even capable of being used in a RMH, though they will not last quite as long as firebrick.

By the way, what kind of area do you live in? If you have a back yard and there is clay soil, you can build a perfectly functional rocket stove entirely from that (plus some sand and straw).

Thank you both; that's very helpful.

Glenn, I live in a rural/residential zone here in Illinois (45 min west of Chicago). Since contractors love to scrape off all of that topsoil and sell it, my soil definitely runs on the clay-ish side of things Don't know if it's any good for brick or cob making though....what makes for good clay?

If you can take a damp lump of the clay and knead it smooth, then roll it out into a sausage that can be bent some without breaking, you have adequate clay for cob. The longer and thinner you can make it without it breaking, the better it is.

I'm finding quite a few of these Chicago Commons bricks in my area from multiple sellers. They look like the ones in your picture.

https://chicago.craigslist.org/chc/mat/5054530776.html

Alex; yes, those look like old clay bricks, won't last as long as firebrick in the hot part of your core , but should work just fine. .35 per brick by the pallet seems pricy to me , .10 would be better, H.D. sells new and used clay brick at .40 by the brick but they are not the old baked clay brick. Look for the best deal then try haggling the price down. Maybe you could find some to demo yourself ?

Well, yeah, that would be better Unfortunately, bricks seem to be somewhat pricey here in the Chicago area....most I've seen are going for at least .50 per brick, especially if they're sold in smaller amounts.

Alex,   I remembered this post from a while back on various types of bricks and their descriptions. In particular Erica Wisner's post:

https://permies.com/t/30551/Fake-fire-brick

1. Look at the proportion of impurities in refractory bricks.Generally speaking, impurities will be produced during the sintering process of refractory bricks strictly according to the proportion of ingredients, which is no problem. However, some manufacturers often do not produce according to the proportion of materials used, so that the sintered refractory bricks do not have a hard structure, so that the quality of the sintered bricks is not good enough, and then deceive consumers with high prices. Then when you buy refractory bricks, you can check it through its surface. Generally, the surface of refractory bricks with high impurity content will be very rough, while those refractory bricks that meet the quality standards have uniform overall color and smooth and flat surface, which we can intuitively distinguish from the surface.
2. It is the sintering experiment of refractory bricks. This method is effective. Generally, when we buy refractory bricks, we will go to the manufacturer to check. Especially before we decide to buy, we must ask the manufacturer to conduct a high-temperature test to check whether the sintering index of the refractory brick is the same as the standard index. As long as the deviation of the experimental results is not large, the quality of the brick body is still acceptable, which is also a good method. If you have doubts about this method, you can use the second method for detection.
For more information on identifying refractory bricks visit
https://www.zj-refractory.com/article/d_6441eac0e3670209c71546fc.html

How can i send a pic in this thread to help me determine if these are antique refractory bricks?  

thomas rubino wrote:Alex;  You do not have to use firebrick if you can't find any ,especially if this is an occasional use rocket stove. Regular clay brick will ultimately crack from the heat but this could take quite a while.  Most firebrick you will find are the dense heavy ones ,noticeably heavier than a standard brick. Most but not all will have a name or sometimes a number cast into it. They generally are a white /yellow / color. sometimes tinted red from heat .clay brick that is old will draw a line on the sidewalk  just like a piece of chalk , newer clay brick won't do that. Old clay bricks sometimes are solid and sometimes they have 3 large holes thru them to help hold them together when cementing. Fireclay  is something you should be looking for while scrounging. I've included 2 photos, the bricks in the sled are all fire brick and the ones stacked by the wall are old clay bricks.

I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

Hi Madeleine;
There are no published plans for building a Shorty Core.
Peter graciously supplies them to anyone who asks.
Unfortunately, batchbox temperatures would destroy plain clay bricks too quickly.
A  J-Tube build could be built with plain brick as long as they are occasionally checked for deterioration.

A shorty core has no metal parts other than the airframe and door.
A first-generation batchbox uses a metal air tube and a metal door, both would need to be locally fabricated.
I do sell a book on constructing this style core, and another on building a door for it.

A  J-Tube requires no metal, although there is an upgrade to the feed tube that is made from metal and can be added if desired. (Peter channel)
A J-Tube can be built directly into a brick bell or it can use a barrel.
A  J-Tube can be easily built by a novice with minimal coaching.

Madeleine Innocent wrote:I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

What size do you want to build? Straight one or sidewinder? I am able to provide you with the core drawing in ISO or Imperial measurements. What do you prefer, pictures of every layer, drawn out brick by brick, or the original SketchUp file? Free to use, no charge.

Small donations are appreciated, although not mandatory in any way.

The design of the bell is done  by Thomas Rubino and Gerry Parent, ask them for guidelines.

Peter van den Berg wrote:

Madeleine Innocent wrote:I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

What size do you want to build? Straight one or sidewinder? I am able to provide you with the core drawing in ISO or Imperial measurements. What do you prefer, pictures of every layer, drawn out brick by brick, or the original SketchUp file? Free to use, no charge.

Small donations are appreciated, although not mandatory in any way.

The design of the bell is done  by Thomas Rubino and Gerry Parent, ask them for guidelines.

Thanks Peter. I go through bouts of excitement to start then bouts of overwhelm. I don't think it's so much the work as the timing (it will be where my wood stove is, so currently have 2 months) and giving myself time to change consciousness from normal work (right brain) to left brain.  There is so much info about them, I get overwhelmed easily.

I'm not in a super cold area - no frosts, so the design can be relatively simple, to my mind. I'd like it to look good as I'd hate to think the people who come after me rip it out.

Peter van den Berg wrote:

Madeleine Innocent wrote:I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

What size do you want to build? Straight one or sidewinder? I am able to provide you with the core drawing in ISO or Imperial measurements. What do you prefer, pictures of every layer, drawn out brick by brick, or the original SketchUp file? Free to use, no charge.

Small donations are appreciated, although not mandatory in any way.

The design of the bell is done  by Thomas Rubino and Gerry Parent, ask them for guidelines.

I had bought a Walker plans last year, but now can't find them. So that must mean I need to keep looking. I looked at your site Peter and I liked the brick sidewinder. I have a lot of bricks! I think the greater the detail the better!

Peter van den Berg wrote:

Madeleine Innocent wrote:I'm finally ready to start looking at plans and building a RMH. I don't have any fire bricks, and if I don't have to have them, as you mention, then I won't. I really like the look of your shortie. Can I buy the plan to compare with the plan I have?

What size do you want to build? Straight one or sidewinder? I am able to provide you with the core drawing in ISO or Imperial measurements. What do you prefer, pictures of every layer, drawn out brick by brick, or the original SketchUp file? Free to use, no charge.

Small donations are appreciated, although not mandatory in any way.

The design of the bell is done  by Thomas Rubino and Gerry Parent, ask them for guidelines.

Hi Peter, I did go to your site and downloaded the plans of the sidewinder but my computer doesn't seem to have the necessary software to view it.

OK, you don't have the Sketchup application. By the way, the Shorty core isn't published on the site as yet, so much to do before I am getting too darn old...
But I can provide you with jpegs, of every layer of the core and you can work with that. I understand you are in Australia, the firebrick sizes might be different.
So, what are the firebrick measurements you are able to buy?
Is a Shorty sidewinder core the type that you want, or just the straight one like Thomas has built?

Madeline,  you wrote--

"Hi Peter, I did go to your site and downloaded the plans of the sidewinder but my computer doesn't seem to have the necessary software to view it."

This Sketch Up software is fairly easy to download,  and even if you use it just enough to confirm measurement it can be helpful.  Peter does a great job getting the measurement wrote (scaled) for your  AVAILABLE brick sizes.   This I believe is important, as sometimes a lot of cutting can be saved due to different layouts of your available brick sizes.  Simply said, what works in one area of the world can be different in another part.  (this is not the dimensions per say, but rather the  brick pattern layouts)

Brick sizes around the world certainly vary. Which makes sense,  as many of the measurements are rounded to even numbers,  whether if is imperial or metric numbers

Best of success to you.
Scott

Brick sizes are:
The new firebricks 230/115/75mm ($5.95) or 230/115/25 ($4.80)
Some variations 305/305/50 and 230/115/75/63 or 51
Reclaimed ones seem to be 230/110/65 ($1 - $2.75)
I haven't seen the $1 ones at my local salvage yard yet, as I wasn't sure of numbers.

I tried to download Sketchup but it won’t let me on my desk top.
I don't want to be a pain for Peter as he is so busy.

I am confused over that software, its not free in Australia, andthe i ternational one requires no downloading.
How can I use a downloaded drawing?
Also, I read the full build of the Shorty by Thomas earlier.
Is it the same, because it seemed to have plans attached?

I downloaded a .skp file of the shorty core, and was able to open it in a free online Sketchup viewer/editor. It was an option something like "open a file from your device."
https://www.sketchup.com/en/plans-and-pricing/sketchup-free