When did people start using “rod” for “ wrought”? [closed]

I’ve seen many online postings for people claiming to sell “ rod” iron rather than “wrought “ iron items.

rod iron is just a spelling error:

Wrought iron has been worked (wrought) by hammering and bending, often into elaborate shapes. It is distinguished from cast iron, where the iron takes on the shape of the mold the molten metal was poured into.

There is such a thing as “rod iron”—iron shaped into rods—but this is a rare specialized term. Most instances of this form are erroneous spellings of “wrought iron,” as are all instances of “rot iron.”

(Paul Brians, Common Errors in English Usage and More, Washington State University)

From the website of American Iron :

Today’s terminology for ornamental iron can be somewhat confusing. What is it? “Rot iron”, “rod iron” or “wrought iron”? The best place to begin is probably with the spelling. It’s actually wrought iron. Wrought means “worked”.