Mill Sheet is an untrimmed piece of pewter just as it appears after the final rolling mill pass.
The edges are unfinished and not perfectly parallel, and the ends are neither straight nor perpendicular to the edge. Thicknesses across any dimension may vary +/- 0.004″, and the widths and lengths available vary depending on thickness. Quoted dimensions are nominal values; all will vary from sheet to sheet. Pewter in these sizes is not perfectly flat initially, but will become flatter with time.
This form is mostly specified when maximum dimensions are required, such as for a counter top, or when the final size of the sheet is undetermined.
See our Mill Sheet Dimensions Chart (PDF) showing the dimensions available at various thicknesses. These dimensions are guidelines and can be adjusted to suit your specific application.