In the seventeenth century, shirts were made of unbleached linen, the fabric varying from coarse canvas to fine weave, and ranged from brown to off white in colour, although unbleached linen could take on a grey or even greenish tinge. The finest shirts could be almost white, the fabric was generally bleached by being left out in the sun, but the white of the 1640s was nowhere as bright as the 21st century brilliant white achieved by modern detergents and their additives that counteract the natural yellowing of fabrics that have been worn for a while. The haymaker on the right shows that it was the fashion to take off your coat and work in your shirt if it was a hot day. Notice the detail on his collar and neck opening.
They were cut square and long, with front and back usually made of a single piece of fabric, gathered into a narrow neckband. Gathers can be simple for a plain shirt or of extremely fine cartridge pleating for a high status one. The image on the left courtesy of Manchester Gallery of Costume is a surviving shirt from our period. It's described in more detail in another post below.
As you can see, they were generally long enough to reach mid thigh or even knee length. This rather saucy image from A Letter To Mr Marriot 1652 (Mr Mariott was a famous lawyer and notorious glutton of the time) shows the length of the shirt because his breeches are around his ankles. The side seams would be left open for about 12 inches to allow the shirt to fit comfortably down the legs when worn under a pair breeches.
The sleeves would also be cut square and gathered to a narrow cuff, which may be secured by ties, small buttons or a t-bar (like a fabric cuff link) if it's posh. The sleeve is then sewn square onto the side of the shirt with gussets under the arms to provide some ease when you put it on over your head. There should also be smaller triangular gussets where the collar meets the shoulder seam, to give extra strength and prevent tearing. Photos of a shirt made by Tricia Webb.
At the front there should be a simple straight hemmed front opening large enough to let you put it on over your head. This opening was secured by a pair of ties, sewn to the collar or passing through a single sewn eyelet on each side at the neck.
Here is a nice repro pair of posh ties by Gina B
The shirt as such would not have any more than a small standing collar of perhaps an inch and a half wide. To this a falling band may be tacked on. Shirts were not generally made with integral collars in our period. For common soldiers a small band can be used, just large enough to cover the standing collar on the coat. There are no images showing soldiers wearing knotted cloths or tied stocks for our period. A small plain collar seems to have been the fashion for just about everyone.
This is one I made earlier, with a posh vicar's collar attached:
Here are a set of sleeves made up for a copy of a blackwork embroidery shirt in the Warwickshire Museum. Note the construction and the gussets. The picture comes from a blog that tells the story of how it was made. Well worth a look.