Are old bricks hazardous?

I read Tim Barker's book on rocket ovens. I thought it was awesome and immediately took action to build my own outdoor oven. The first step was finding some used bricks online, which I managed to do. The bricks were from an old outdoor patio built in the 1960s. Most had a little mortar residue on the surface, some had larger chunks of mortar stuck to them. They were in great shape otherwise. I later read online that old mortar may contain asbestos. Now, it's not like I'm breaking up the bricks or mortar, but I'm a little worried about this. Am I putting myself at great risk when doing this? I'll be covering the whole thing with cob insulation at some point, so it might not even matter.

I just want to hear a risk vs. reward analysis from some people who know anything about it. I'm very much in agreement with Kiko Denzer, who advocates finding rather than buying materials when possible.

The risk is possible, but it can be managed. For asbestos to cause harm it has to be drawn into the lungs as an aerosol or ingested into the digestive tract. If it's a wet blob of goo and you're wearing an industrial quality respirator, your risk is mighty low.

Douglas Alpenstock wrote:The risk is possible, but it can be managed. For asbestos to cause harm it has to be drawn into the lungs as an aerosol or ingested into the digestive tract. If it's a wet blob of goo and you're wearing an industrial quality respirator, your risk is mighty low.

If I'm cooking bread outside with the oven, I'm certainly not going to be wearing an industrial respirator. There's also no wet blob of goo; the mortar is dry. The patio was ripped out of the ground and the bricks were left there.

Okay, pardon me, I misread -- you have an existing structure not a pile of bricks. (It's been a long day.)

How does the mortar look? Is it breaking down, crumbling, creating dust? That's the highest risk situation. If it's sealed, it's low(er) risk.

Let me share the situation again. I'm building a rocket oven with reclaimed bricks (right now it is just a pile of bricks sitting in my backyard). I took the brick from someone who ripped a brick patio out of their backyard. That patio was built in the 1960s, so the mortar is totally dry. My rocket oven is not yet built. Most of the bricks I took have a bit of mortar residue on the surface. Some have chunks of mortar. The mortar doesn't appear to be crumbling, but I'm not expert.

The rocket oven will be outside in this case, so whatever asbestos there is would be diluted in the air I guess.

Right, third time lucky (duh!).

Personally, I would wet everything down and build, build, build. Wet asbestos doesn't travel.

I see. Do you think I should get rid of the brick and just buy new? I'm kind of thinking maybe I should just do that at this point. Won't even be able to enjoy the thing if I'm constantly worried about using it.

I guess I know what I'm doing is risky, but I'm trying to get a read on "how risky"?

Sorry for any confusion. I personally think that your risk is extremely low and I would not lose any sleep over it. My 2c.

You do understand that many of the old red bricks were low fire and a low fire clay and can potentially disintegrate in a high temperature environment?

For example if I made bricks with my clay here they will bisque fire at cone 6 but try and take them to cone 10(fire brick will handle cone 10) and they sort of melt and sort of go mushy.  The result looks sort of like lumpy oatmeal.

My grandfather was a bricklayer who specialized in fireplaces, coppers (giant pot larger than a modern bathtub with a rocket-ish fire under) and other things that had fire and bricks combined.  He reused bricks all the time and for the first ten years or so, his job was cleaning used bricks,  some of which went back to Tudor times and before.  There was no problem reusing so long as they were cleaned (hit the unwanted stuff with a hammer as if knappig flint, but keep your thumb well and truely out of the way).

I learned from him that there are a lot of very different things called bricks and depending on the heat of the fire, you use different kinds of bricks.

The red bricks would be good for temperature that is hot enough to be uncomfortable to touch, but wouldn't burn your hand after one minute.  So structure and outside would be made of red house bricks. For a normal fireplace for cooking and heating, cinder bricks and then next to the fire would be fire bricks.  (They probably have different names now).

For something that burns really hot like a copper, just about all of it would be a special fire bricks and special mortar mix.  There would be an insolation gap of air between these and the outer red brick so they didn't get too hot.

Keeping in mind, this is a man that didn't trust those modern post war bricks as they couldn't take the heat as well as the 19th century bricks. I think the science and kiln technology has improved since he retired.  

That is very oversimplified and there are lots here who know the science that can help.  But there are three things that I cemented into my memory from his long descriptions of his work.
1. Different bricks for different kinds of heat and different jobs
2. It's okay to mix brick types depending on what job they are doing.  Ie, fire bricks inside, building red bricks on outside.
3. I never ever want to be a bricklayer even if they don't have to work in the rain.

Hey Andrew,
I second Douglas' opinion. The dangerous part (if there was one) was breaking the mortar. If you want to be on the safe side, wear a mask and wet everything down while working (removing the bigger lumps of mortar).
For the actual brick laying it's also goo to have the bricks moist.

I am very interested in your rocket oven design. What type oven are you building? I get a lot out of "sharing notes". You can check my latest out here.

C. Letellier wrote:You do understand that many of the old red bricks were low fire and a low fire clay and can potentially disintegrate in a high temperature environment?

C. you may have a point here. But those temperatures will only occur in the core (feed, burn tunnel, riser) and maybe at the transition from riser to oven. Here firebrick would be the best choice.

Benjamin Dinkel wrote:

I am very interested in your rocket oven design. What type oven are you building? I get a lot out of "sharing notes". You can check my latest out here.

I'm building the rocket oven pretty closely to the plans laid out in Tim Barker's book The Rocket Powered Oven eBook. The only difference is that he uses steel stove pipe for the heat riser instead of brick. Here is a link to a few pictures: rocket oven pics. It's just a dry stack at this point, but it stands on it's own and the mortar would just be to seal and level the whole thing and then cob for insulation. I included some pictures of bricks that have chunks of mortar on them.

I know that some other material would probably be better. BUT, I think that an oven like this one is a.) complicated to make correctly and b.) might not be practical / enjoyable to use. I've noticed that I get tired of things quickly. So I try to do things (the first time at least) with as little money spent / with found materials taken out of the waste stream. If I don't like the rocket oven or it doesn't work well, then, hey, this stuff was going to be trash anyway. No harm, no foul.

If I use the thing so much that it breaks, that's a good thing! Then I build it using better materials next time because at least I know I'll use it.