The Fresh Loaf

A Community of Amateur Bakers and Artisan Bread Enthusiasts.


sourdough greg's picture
sourdough greg


The good news is I've started making my oven. 42" frost line depth here in northern Illinois. So... had some old firebricks around, but they were kind of dirty, and my wife wanted me to wash them (as well as some of the cruddier ones I built with). So, after  cleaning the bricks in a water/Simple Green cleaner solution (all of the building materials were dug out of the yard, so pretty filthy, hence the cleaning solution rather than just water), I read the back of the cleaning bottle. NOT FOR INTERNAL USE, and other such warnings. My question, will this stuff stay in the firebrick forever? Will it rinse out with regular water? Will it "burn" out whan I fire the oven? It was a probably ahalf cup of cleaner to a gallon and half of water, so it was pretty diluted. Will I kill everyone who eats bread out of this oven if I use these bricks?

So far, I've managed to scrounge and not purchaseANY materials. Unfortunately, I don't have enough firebricks if I don't use these, and would have to purchase some (which I really don't want to do.


Thanks for any input/suggestions.


jeb's picture

Muriatic acid (hydrochloric acid) is used as a cleaning solution, and I definitely wouldn't want to take it internally, but I wouldn't hesitate to eat bread baked on brick that had been cleaned with it. So, it's important to know the ingredients of the cleaning solution.

SulaBlue's picture

For using SimpleGreen to wash dishes with, just FYI.

To clean with Original or Lemon Scent Simple Green All-Purpose Cleaner:

  1. Use a 1:1 to 1:10 solution of Simple Green and water.
  2. Apply by spraying in sections and scrub with a non-abrasive brush or scrubber.
  3. Follow with a thorough rinse to insure a residue free finish.
  4. Wipe dry with a lint free cloth or towel.
Granted, while plates and glasses wouldn't absorb any, there's a chance that plastics would, and they do suggest a thorough rinse. However, they're working at a 1:10 ratio here. At 1/2 cup to a gallon and a half of water you're looking at  1:48 (16 cups per gallon). 
You could always call the company, but I *personally* wouldn't be particularly worried about the miniscule amount that might have been soaked into the bricks. You could always soak/rinse your bricks if it'd make you feel more secure.


baltochef's picture

I would call both the manufacturer of the Simple Green, as well as several places that sell, or build, wood fired ovens to get several opinions..Fire Brick is less porous than building brick, but still much more porous than anything that one eats off of..Plastics are not particularly porous, but when heated up in microwave ovens they do get soft, with the result that fats and flavor molecules that adhere well to fats will transfer into the molecular structure of the plastic, creating a more or less permanent bond..With the result that plastics pick up flavors, and or become stained (think tomato sauce)..

I would be cautious until someone with experience, preferably a wood fired oven mason, told you that it was OK to build with those bricks that you cleaned with the Simple Green..My gut instinct is that the 700F-1000F plus temperatures in a wood fired oven will destroy the cleaning compounds in the Simple Green and outgas any residue left in the fire bricks from the cleaning, but I could be very wrong..


Yerffej's picture

In the past there has been a widely accepted train of thought that toxic substances in very small doses will do no harm.  I think that this sort of thinking is false and if they were my bricks I would make very certain that they can be 100% cleared of any and all harmful materials.


Smo's picture

I say go for it.  The simple green website has material safety data sheets here:

The one for Simple Green All Purpose Cleaner (what I think you used) says that it's pretty mild  when swallowed, and that the only ingredient with established exposure limits is 2-butoxyethanol, which boils at 340 F - so just don't bake in it the first time you fire it, if you want to be really cautious.

ClimbHi's picture

if, after the initial tempering firings, there was any trace of the cleaner left. But I'm no chemist, so what do I know? If it wuz me, and it ain't, I would feel pretty comfortable using the "cleaned" bricks on the dome, but I'd  probably spring for new ones for the hearth floor on the theory that, if there is any harmful effect from the cleaner, the food would not be in contact with the "contaminated" bricks on the dome.

As for outgassing (vs. direct contact) I wouldn't worry about that at all. The gasses in an oven stay above the floor of the oven a distance of about 2/3 the height of the door and up. (This is particularly evident when you first fire an oven -- the smoke will form a distinct line at this height and never go lower. The wall bricks stay clean although the higher bricks turn black with the soot created by the fire.)

As for seeking the advice of an oven mason, I wouldn't bother. A mason knows about stone and morter -- not about chemistry. You need to get in touch with the mfgr and get their take. They may simply tell you not to use the bricks since they don't wanna be sued. (And you can't fault that logic.)

That said, never take advice form anyone over the Internet where your health is concerned. ;-)

Pittsburgh, PA

baltochef's picture

The more I think about this question the more I think that the bricks should not be used where food is concerned..Some chemical compounds need temperatures approaching 2000F to completely destroy them..Since WWII there are hundreds of thousands of chemical compounds that do not occur naturally in nature that humans are exposed to constantly..As much as scientists think they know, I an convinced that we know very little regarding the long term consequences of constantly exposing ourselves to not just a single chemical compound daily, but to literally hundreds of different chemical compounds that we have no clue as to their long term toxicity..

If it were my decision to make, I would eat the cost of purchasing new fire bricks, and chalk it up to experience..

Just my 2 cents worth..


taramacon's picture

I'm sorry but I think that I would be much more worried about what they were used for before you found them. Fire brick can be found in many industries that would make me question what their history is. Many retorts have been used in this country and there is no part of a retort that I would use. As far as the soap that would not worry me in the least but I would pre-fire the oven as others have suggested.