Edge does not follow area
Take the default list: four card panels with 17 inches of edge each and one body with 25, so 93 inches — nearly 8 feet — in a single wallet. A belt blank 48 inches long and 1-1/2 inches wide has 99 inches of edge, barely more, and it is one piece rather than five with a cut edge all the way round each. That is the whole reason small goods take longer per item than anybody expects, and it is invisible on a cutting list, which lists areas.
Ten wallets is 77.5 feet of edge. At two sanding passes, two burnishing passes and two coats, that is 465 feet of edge actually worked.
Hands-on and elapsed are different numbers
Those 465 feet at the default rates come to 5 hours 10 minutes of hands-on work — 1 hour 33 sanding, 2 hours 35 burnishing, 1 hour 2 painting. Add two coats with a 30 minute wait each and the batch occupies the bench for 6 hours 10. Now run one wallet instead of ten: hands-on drops to 31 minutes but the waiting stays at an hour, so the bench time is 1 hour 31 for one wallet against 6 hours 10 for ten. Ten times the work for four times the elapsed time.
That is the batching argument in one line, and it is arithmetic rather than opinion. It is also why the page keeps the two totals apart instead of adding them into a single hours figure.
Materials are not the cost here
At 160 feet a bottle, 155 feet of painting for the batch of ten is one bottle, and one bottle over ten wallets is a fraction of a cent per item on any normal bottle price. The hands-on time is 31 minutes a wallet. Whatever your hourly figure is, the paint is a rounding error against it. The page prints the per-item paint cost at four decimal places rather than showing a tidy $0.00, because $0.00 invites exactly the wrong conclusion.
Where your own rates come from
The rates in the form are placeholders and they are the input that swings the answer hardest. Halve the burnishing rate and the batch gains 40 minutes. The only way to get a rate that predicts is to time yourself on one real edge with a stopwatch running from picking the piece up to putting it down — the handling seconds are most of what separates a useful rate from a fictional one. First passes over rough cut edges also run slower than later ones, and if that gap is big in your shop the honest approach is two runs of the page and an addition.
Questions people ask
How long does edge finishing take on leather goods?
For the wallet in the form — four card panels and a body, about 7.75 feet of edge — two sanding passes, two burnishing passes and two coats of paint come to 31 minutes of hands-on time per wallet at the default rates. Ten of them is 5 hours 10 of hands-on work plus an hour of drying, and the drying hour is the same whether you make one or fifty.
Why does a batch take so much less time per piece?
Because drying happens in parallel and working does not. One wallet takes 31 minutes of work plus 60 minutes of waiting, which is 91 minutes of bench time. Ten wallets take 310 minutes of work plus the same 60 minutes of waiting, which is 370 minutes for ten — 37 minutes each rather than 91. The page separates the two totals so the effect is visible rather than buried.
How far does a bottle of edge paint go?
That is a field on the form, not a figure this page states, and the honest source for it is your own count of how far the last bottle went at your coat thickness. What the page does with your number is turn the batch into feet of painting — coats times total edge — and divide. Bottles get rounded up because a part bottle is still a bottle you had to buy.
Should I count edges that end up inside a seam?
No, and the field says so. An edge that ends up under a fold, inside a turned seam or glued face to face never gets sanded, burnished or painted, so putting it in the list inflates every figure the page produces. Measure only the edge that is visible on the finished piece.
How many coats of edge paint should I use?
The page has no view on that and the form treats it as an input with a placeholder of two. The number that suits a job depends on the leather, the edge preparation, the paint and how the finished edge is supposed to look, and none of those are things a calculator can see. What it will do is show you what an extra coat costs in time and in paint before you commit to it.