Quote Originally Posted by Morris of Heathfield View Post
By "dark" tartans, do you mean tartans in the "modern" colors? These colors date back to the mid-19th century when chemical dyes were developed which eventually replaced the vegetable dyes. The vegetable dyes were generally lighter in hue than the chemical dyes that replaced them. The "ancient" colors are an attempt to reproduce the old vegetable dyes—or at least, what those dyes looked like after a hundred or so years of fading. The split between "modern", "ancient", and "weathered" tartans only goes back a half-century or so. Peter MacDonald has a good article on the subject here.

Or, by "dark" tartans, do you mean tartans in "dark" colors such as black, blue, and green? If so, then I would be interested in learning Scarlett's theory behind their origin. 18th-century portraits of Campbells wearing tartan usually show them wearing red and black tartans and, from what few portraits I have seen, black-blue-green tartans do not seem to have been worn by anyone except members of the Black Watch during the 18th century, but I have wondered if such tartans are what Scarlett meant when he referred to the "MacDonald type" of tartan here.
They were completely capable of developing dark colored tartans with vegetable dyes. I met a Lass at the STM who dyes wool herself using traditional techniques and natural sources to dye wool. She very quickly explained how simple it was to get as bright or dark a thread she desired.

Here's an interesting article on the Black Watch tartan: The Original Military Tartan