What Drives Production of Tartan Variants?

[OC Richard]

I was noticing that some of the more common tartans have lots of variant options (weathered, muted, hunting, dress) and some of the less common ones don't. Aside from raw demand, what drives availability of these variants?

I think in a way you've answered your own question, by pointing out that it's the "more common tartans" that have the most variants.

Royal Stewart has to be the champion, with numerous variations, at least one going back to the 18th century.

There's Prince Charles Edward Stuart, which is a variation of RS in the proportions.

Then there are all the RS ground-colour variants, with the ground changed to royal blue (MacBeth), black, sky blue, white, grey, camel, green, etc.

In the early 20th century the "ancient" or "vegetable" colour-scheme appeared and was immediately popular.

Then beginning in the 1940s the "reproduction" or "weathered" colour-scheme appeared.

House of Edgar introduced their unique "muted" colour-scheme.

All of these palettes could be applied to any tartan, but as you say it's driven by the popularity or commonness of the tartans.

Dress tartans (with added white stripes) are mostly seen with very common old tartans like Black Watch, MacDonald, and especially Gordon. I've seen Dress Gordon curtains, bed coverings, carpets, etc.

Sometimes the palette is built into the tartan itself, one could say. The example I think of is Flower Of Scotland, which is a variant of Gunn in ancient colours. I can't recall seeing Flower Of Scotland in modern or weathered colours, though in theory these should exist.

Then there are tartans which seem to defy being put into the trio of modern/ancient/weathered colour-schemes, like Isle Of Skye, despite its huge popularity.