Question:
We are a small ornamental iron shop.In an effort to offer a more durable outside railing to customers, we have been manufacturing our ornamental iron designs from aluminum using traditional structural, just as with wrought iron, one-inch-square tubes, one-half-inch punched channels for framing, one-half-inch square solids for balusters, molded top rail or a channel for a top cover.
Question:
Your response to “Pretreatment Over Pretreatment” in the February Painting Clinic should be amended to warn him that running aluminum through an Iron phosphate spray washer would make the sludge in the washer a hazardous waste (according to an earlier comment you made about a year ago). I believe the problem is created by the definition of acid washing of aluminum is a categorical hazardous waste (by EPA definition). When he cleans the washer, all the sludge that is normally sent to the landfill or flushed down the sanitary sewer would be considered an illegal disposal of hazardous waste.
Question:
I believe that a correctly passivated stainless steel must be exposed to air to enhance and continually reinforce the passivated microscopic layer present on the surface.
