You wrote: >>> Pvt. Rubin Nations of the 12th Louisiana (also made up of central and northern parishes) was photographed wearing a dark blue cotton jacket, as was another member of this same company. <<<
Private Reuben H. Nations was a member of Company I, 12th Louisiana Infantry from Union Parish. The photo of him was taken at Camp Moore wearing a uniform purchased there using funds supplied by the Union Parish Police Jury (Louisiana's name for the county level legislative body). This regiment arrived at Camp Moore in July 1861. I would be interested in knowing how you concluded that the uniform was blue in color and not dark gray. There is nothing wrong with blue - Louisiana State Militia uniforms were blue.
A member of Company E, also from Union Parish, wrote that his company purchased a uniform of Gray cashmere at Camp Moore in July 1861 with money given them by the Parish Police Jury when they left home. This "cashmere" uniform (aka cassimere) was a plain weave or twilled woolen or worsted fabric with a clear finish, woven with hard spun yarns. Often made with worsted warp and woolen filling or sometimes with a cotton warp and worsted or woolen filling in a two up, two down twill weave. The fabric was lustrous, light or medium weight, and had a harsh feel. [See Fairchild’s Dictionary of Textiles (New York City, 1979].
According to James W. Nicholson, the Claiborne Rangers (Company L) left Homer, Louisiana in early July 1861 wearing home made (presumeable dark gray) uniforms consisting of a round-about coat with horn buttons and matching trousers.
The two Winn Parish companies of the 12th Louisiana may have arrived at Camp Moore too late to acquire proper uniforms before being shipped off to Columbus, Kentucky. Captain Henry V. McCain wrote home in October 1861 from Columbus that Governor Moore had sent them all a "nice uniform" and a barrel of molasses.
The Winn Rifles (Company C, 3rd Louisiana Infantry) were sent to Camp Walker in April 1861 with Police Jury funds to purchase uniforms there. The men then sent their civilian clothes and other unneeded personal equipment home. This information comes from Winn Parish sources. I am writing this off the top of my head, but will give you reference sources for these 3rd Louisiana comments when I get back to my personal archives.
I thought I remembered that the East Baton Rouge company of the 3rd Louisiana Infantry went off to Arkansas in brown uniforms that were replaced sometime in the fall of 1861. I thought this came from Tunnard's book, but perhaps I am mistaken.
One last thought, keep in mind that the New Orleans newspapers in the spring and summer of 1861 are full of advertisements by local merchants offering military uniforms for sale, and these merchants are likely the source of uniforms for the early war regiments such as the 3rd Louisianan Infantry. In spite of the Union blockade!
Hope this helps!
12th Louisiana Infantry Research