Metal Finishing Time Calculator

Each grit step in the progression has a 1-minute minimum regardless of how small the piece is, on the reasoning that no single grit pass realistically takes less than about a minute even on a tiny piece. For smaller and mid-sized pieces, most grit steps land at that floor, so Surface Area has little visible effect on Estimated Total Time until the piece is large enough that the per-square-inch time genuinely exceeds a minute per step -- at that point Surface Area starts driving the total directly.

No -- Grit Steps is set entirely by your Starting Grit and Ending Grit selections and never changes based on Finish Type. What Mirror Polish changes is the 2.0x time multiplier applied on top of the grit-progression time, representing the substantial hand-buffing and compound work that happens after the last sanding grit, not additional entries in the sequence itself.

The 0.3x multiplier reflects that a patina or forced-oxidation finish typically stops at an earlier, coarser grit than a satin or mirror finish, then substitutes a chemical treatment (heat coloring, cold bluing, or an applied patina solution) for further mechanical sanding. Since that chemical step isn't part of this calculator's grit-progression model, the low multiplier represents skipping most of the finer-grit hand-sanding time entirely, not a faster version of the same sanding work.

Match Starting Grit to the coarsest scratches or damage still visible on the piece, not to where you'd ideally like to begin. If forge scale or deep tool marks remain, start at 60-80 even if some areas look further along; if you're touching up a piece that's already been through initial stock removal, 120-220 is more realistic and will give a more accurate time estimate than assuming you're starting from raw stock.