cross-posted from: https://lemmy.today/post/9250689
How do I test cast iron cookware for lead
So I found a griddle that was in pretty bad shape seasoning wise so I stripped it and noticed a small shiny area which worried me about lead. I ordered some lead tests that stated they were for metal (no specifics) and after doing the tests it came back positive. But this got me wondering if iron reacts with sodium rhodizonate, the main ingredient in these lead tests, to give false positives and load and behold it does. I confirmed this with another cast iron cookware that I know 100% never touched lead. So my question is how the hell do I test this? Everyone keeps recommending the same sodium rhodizonate lead test swabs just with different brand names.
Tldr: After stripping a griddle and finding a shiny spot, I tested it for lead and it came back positive, leading to concerns about the reaction between iron and sodium rhodizonate. The question is how to accurately test for lead contamination in the griddle without potential false positives from the test method recommended by others?
Edit: wanted to add some more info. I did experiment with the test themselves to see how reliable they were and they passed it so I don’t suspect its the test themselves but the chemical reaction between iron and the sodium rhodizonate
I feel like I should point out that pure lead is really soft. So soft in fact that you should be able to easily scratch and deform it with a dull knife. Lead will also tarnish really quickly when heated and turn a flat grey color. Because of its low melting point, lead would also be a really bad filler metal for cast iron cookware. It would soften and fall out if you ever overheated the pan.
Try scratching a line through both the pan and the brighter area with the tip of a fork or a dull knife. If it’s lead, the shiny area will scratch much deeper and feel different compared to the cast iron.
Also, filling a hole or a void with lead might be easy, but welding with steel is also easy and probably cheaper from a manufacturing perspective.
I am far from being an expert, but I would think the shiny spot is indeed a repair but with arc welded steel or an iron/nickel alloy. Both of which will be durable, stand up to heat beautifully, and also appear noticably shinier than cast iron even after being heated on the stove.
Usually the worry in old cast iron about lead is because someone might have used it to melt lead for casting bullets or fishing weights.