Chaeley, steel plating was too strong of a term, based on a quick glance through the article.

However, after the engagement, Semmes in his official report says:
At the end of the engegement it was discovered, by those of our officers who went alongside the enemy ship with the wounded, that her midship section on both sides was thoroughly iron-coated. The planking had been ripped off in every direction by our shot and shell, the chain broken and indented in many places, and forced partly into the ship's side. The enemy was heavier than myself, bith in ship battery and crew; I did not know until the action wasover that she was also iron-clad."

Browne in his article says "The chain plating was made of one-hundred and twenty fathoms of sheet-chains, of one and seven-tenths inch iron, covering a space amidships of forty-nine and one-half feet in length by six feet two inches in depth, .... secured by iron dogs, and employed for the purpose of protecting the engines when the upper part of the coal bunkers was empty, as happened during the action. The chains were concealed by deal..."
It is "strange that Captain Semmes did not know of the chain armor; supposed spies had been on board and shown through the ship...."

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