What a dye lot is
Yarn is dyed in batches — a kettle, a vat, a rack of skeins — and every batch is a dye lot. The dye is weighed to the same recipe each time, but water, temperature, the fibre itself and how long the batch sat all vary, and two lots of the same colour can differ by a shade. On the shelf you cannot see it. In a sweater, where one skein ends and the next begins, a line appears across the fabric and never goes away.
Where it is on the band
Every ball band carries a colour name or number and, separately, a lot number — labelled Lot, Dye Lot, DL, Bath or Partie, or just printed as a second number beside the colour. Hand-dyed yarns often use a date or a batch code instead. Undyed and some machine-dyed acrylics say No dye lot, which means the mill considers every batch identical; treat that as advice, not a promise.
How we match
Every skein in an order is pulled from one dye lot whenever we hold enough of that lot. If we cannot make the whole quantity from one lot, we contact you before shipping so you can take the mixed lots, reduce the quantity, switch colourways or cancel that item. Lot numbers are not listed on product pages, because stock rotates constantly — but if you already have skeins and need the same lot, write to us with the number from your band and we will check the shelf before you order.
Hand-dyed yarn
Hand-dyed and kettle-dyed yarns — Malabrigo, Dream in Color, Araucania — vary within a lot as well as between lots; that variation is the point. The lot still matters, but the fix for any visible difference is the same either way: alternate two skeins every two rows through the whole piece. The colour then shifts continuously instead of at one line, and no eye can find the join.
Running short
If you run out with a garment half done and the lot is gone, do not simply knit on with a new lot. Undo back to a natural break — a sleeve seam, the underarm, the start of the yoke, a stripe — and let the new lot take over there, where a shade change reads as design. Failing that, alternate the old and new lots every two rows for as long as the old lot lasts, so the change happens over inches rather than in one row. And next time, add the spare skein.