Hello all, Recently I have come across a problem that I cannot seem to understand. A fermentation room was built out of an insulated wall system provided by a company called BONDOR, started to rust at the corners of the joints between the walls and ceiling. The rivets started rusting as well but to my knowledge, it cannot be the rivets because they are aluminium... Also the screws and sliding door track bolts/washers supplied also started to rust. I phoned the company and was asking if their panels were able to sustain the heat and be used as a fermentation room. Of course they said yes, as I asked before I purchased them of course, but just to be sure, I asked and got it confirmed. They claim that many others use their products to build such rooms with the same material. (Specifications can be found at http://www.bondor.com.au/bondor/brochures/ColdStorage.pdf ) Anyway, they asked me what chemicals were present in the room and during the fermentation process. I told them exactly what was used. The room was used to make bread. Apart from that, additional steam was produced from a machine within the room. Now my question is, what is causing the rusting? The composition of the bread is listed here: Per 100KG of Flour, there'd be 1% Improver 1% Yeast 0.5% Gluton 0.5% Soya 1% Sugar 1% Salt 0.5% Milk Powder With my basic understanding of chemistry, I can say fairly positively that those substances that make the bread do not corrode with the metal sheets of the wall panel system. And I'm sure the company was not lying to us as it is a huge company. So what is causing the corrosion? Summary and Additional Info: The rust eats at the corners between the wall and ceiling, behind an aluminium angle fixed with rivets. The room was hardly cleaned by the workers. Only the ceiling panel was corroded, side panels barely corroded with some patches appearing every now and then. Also at the centre of the ceiling panel, there is a sprinkler system that belongs to the plaza, something we cannot afford to touch. Rivets and bolts/screws provided, all rusted and the room would be left there after the bread was ready to be baked (and then used again to ferment the next batch of bread - this went well into around 20months) Additional substances may be present but the person who makes the bread says that's what makes the bread and no other chemicals were used. Can someone come up with logical statements of how the room started corroding? (The old fermentation rooms were also not cleaned and they were used for around 10 years before corroding, why would this one corrode so fast ie. not even 2 years?) Thanks, Levi.