A STARZ Original Series From Executive Producer Ronald D. Moore: Outlander

[Calgacus]

Regarding earlier questions about the tartan being worn, and Fraser or MacKenzie:
From my reading of the history of tartan, I seem to recall that most agree that before the Ban on wearing of tartan, after Culloden, there were no such thing as uniform "clan tartans", that most Scots, in the Highlands, wore mostly whatever the local weavers wove. Most of those tartans were also made with locally available dyestuffs ( probably mostly plant based dyes). I also seem to recall that what few written accounts were made, commented upon the tartans as also blending in with the local plants, and thus acting as a form of camouflage.
Therefore I believe that it would have been very historically inaccurate, to have the cast wearing Victorian invented "clan tartans", esp. the predominantly red "dress tartans", as I believe we have been told that only the rich could have afforded such colours, in their clothing. I also seem to recall reading that wearing a mix of different tartan patterns was not an uncommon practice, before the banning of tartans.
As for the specific tartan cloth, used in the series, I was chatting with Gordon Kirkbright, today, after buying some his bolt of Gordon PV ( Marton Mills?) tartan cloth, and ( hope it is OK, Gordon, to "spill the beans"?), he told me that he designed and produced the cloth, used for the TV series. He also mentioned that there may be more woven, in the future.

Whilst it would be inaccurate as you say for them to have used the post 1820s "clan tartans", I believe that tartans of the period were probably rather more colourful than those used in Outlander. The painting below was painted in 1746 by D. Morier and he used prisoners from Culloden as his models. None of the tartans are identifiable with modern tartans, but they are decidedly bright and contain a lot of red.

culloden-illustration-460.jpg

[Carlo]

...
Therefore I believe that it would have been very historically inaccurate, to have the cast wearing Victorian invented "clan tartans", esp. the predominantly red "dress tartans", as I believe we have been told that only the rich could have afforded such colours, in their clothing. I also seem to recall reading that wearing a mix of different tartan patterns was not an uncommon practice, before the banning of tartans.
...

I have read on different occassions, that the English army used red coates because the red dye was cheap.