Mills and color substitution questions

[Kevin Murphy]

I am wondering if I were to purchase tartan from a mill would it be likely that the tartan is already in stock or do they weave it in order to save the yarn used?

If there are any posts that anyone could refer me to I will be very grateful
For example lets say I wanted a certain amount of yards in the Ross Hunting Tartan but substitute the red yarn I wanted orange , yellow, or some other yarn they already have in stock.

If it is the case that a mill weaves a certain amount of yards AFTER someones places an order, then it would seem reasonable to ask for a color switch, with consideration for which colors they have available, without an increase in price based on the idea that the work would not be made anymore complicated.

[The Wizard of BC]

Which mill do you have in mind? Some mills stock some Tartans, some mills stock other Tartans.

Each mill picks what Tartan they will carry in stock. And not all that publish a stock tartan list actually have fabric sitting on a shelf waiting for someone to weave it. Sometimes it means that they know the thread count and weave that Tartan in large runs regularly.
These stock weavings are usually of many yards at one time. One mill I know of weave no less than 100 meters per stock Tartan run. This is how they keep the price reasonable.

There are possibly slight color variations due to where the yarns were dyed and the dye lots but anytime you want to change a color beyond what a weaving mill calls their stock list you are now into a custom weave job.

Each mill has a different minimum yardage for a custom weave. This can range from 11 meters up to 65 meters. This is due to the labor involved in warping a loom and the physical limitations of the loom itself.

Just a small color change could mean that you have created a totally new Tartan. For example if you add a yellow line or stripe to Ross Hunting you no longer have Ross Hunting.

You have to remember that most Tartan weaving mills do no have the thousands of yards of yarn, in every possible color, sitting on a shelf somewhere. They usually order the yarn as they need it depending on their stock weaving schedule.

One run of double-width cloth can easily take half a million yards of yarn.

[Kevin Murphy]

Thank you Steve. that was very helpful and answered all my questions. I don't about how they do things. This makes a lot more sense now.

[Grizzled Ian]

Kevin,
Another thought occurred to me while reading the 3rd para of your OP. Steve refers to it briefly in "warping a loom".
If the mill is going to make just a small change in the colours used at the end of someone else's run, it's not only the weaving thread that you change. You have to make the same change in the warp-wise threads on the loom as well - if you want a proper Scottish tartan that ends up with the thread count across the material to be the same as up and down.