This short poem sets two odd images side by side and lets the reader work out the link. The first is a black coat for winter, described as old as the fashion for boiled calf's head, a dish that sounds long out of style. The coat feels heavy, dark and out of date, something put on against the cold, as the title "Preparations" suggests.
The second part turns to a question: has the art of subtraction set the speaker up with a "wife of paper"? Subtraction might mean cutting, as in paper-cutting, or it might mean loss, taking things away until only a flat figure is left. Judging by the wording, the speaker feels a quiet loneliness, treated with dry, wry humour. The paper wife seems fragile and not quite real, a stand-in for company.
The mood is wintry, wistful and a little strange. The poem doesn't explain itself, so the feeling comes from the coat's weight and the paper's thinness.