Green’s Dictionary of Slang

the most basic part of something; thus get down to hard-pan, to get down to basics, to come down to fundamentals.

1852		W.B. Pike in N. Hawthorne and Wife (1885) I 444: You are the only one who breaks through the hard-pan [DA].
1861		O.W. Holmes Elsie Venner I 168: Mr. Silas Peckham had gone a little deeper than he meant, and came upon the hard-pan, as the well-diggers call it, of the Colonel’s character, before he thought of it.
1873		T.B. Aldrich Marjorie Daw 168: He’s a realist,—believes in coming down to what he calls ‘the hard pan’ [DA].
1882		W. Besant All Sorts and Conditions of Men II 96: And as for business, it’s got down to the hard pan, and dollars are skurce.
1885		Leicester Chron. 18 Apr. 5/6: It is here, when we ‘get right down to hard pan,’ that we English are strong.
1902		Ade Forty Modern Fables 5: It put a Sickening Crimp in his Visible Assets and moved him about three Notches nearer to Hard Pan.
1908		Springfield (MA) Weekly Republican 13 Feb. 3: It will be well for Springfield to get down to hard pan [DA].
1916		O.O. McIntyre New York Day by Day 13 Mar. [synd. col.] [They] are going to have to get down to hard pan shortly, or go to work.
1926		Aberdeen Jrnl 15 Sept. 5/6: The British will see more and more of their trade slip away if they neglect to get ‘down to the hard pan of work’.
1929		W.D. Edmonds Rome Haul 118: Now you’re down to hardpan, what you going to do?
1952		I. Bolton ‘Many Mansions’ in N.Y. Mosaic (1999) 349: He had done with women. They didn’t jibe with work. The sooner he was down to good hardpan, the better – loneliness, misery, solitude.