At the kind request from the Izannah Walker Doll group to post on the differences of these early fasteners, I have taken a few snaps of some early hook & eye fasteners on different gowns here at the Museum. I am by no means an expert, but I think I will be able to help you all descirn the different between an early, and modern type of hook & eye closings.
I know metal hooks have been used for closing clothing since the 1300s....used with crochet loops instead of hard wire ones....but I dont start to see them commonly used as fasteners until the late 1820s. The picture above and below, is a c1835 girls dress, for a petit 7 or 8 yr old. Early hooks & eyes were made of copper, then most commonly brass until the 1850s....twards the 1860s I have seen blue'd steel, blackened steel in the 1870s and to the 1890s, brass again as well as the black, which were advertised to be rustproof. Early examples do not rust at all, but they do tarnish~ the brass ones turn green and can discolor the fabric around them, so it is always advisable to lay a buffered acid free tissue between the hook/eyes and the dress fabric when storing.
Speaking of the eyes.... both hammered and not hammered are common, and not really a good way to tell the date of a garment(assuming they are original to it) This is the most common shape however, and if you see some weird fancy scrolling or hookey-do to the eye, then it is probably a later 19th early 20thc piece.
These brass hooks are original to this mid 1830 silk girls dress. The hook part itself can be found to be hammered nearly flat on the very edge (these are NOT)....those tend to be found more twards the 1860s and later.
Looking down, if you enlarge the picture, you will be able to notice the main difference between early hooks, and modern ones. What do you think it is???
On this 1840 dress, you can see plainly that the hook is made from a single piece of wire
This picture shows a brass fastening set c1890. Note the triangular shape of the eyes, and the 'hookey-do's' I mentioned earlier~ this wide area was supposed to give you more area to stitch onto the fabric, spreading out the constant tension, so the fabric would not rip out as easily.
This picture shows, tho a little blurry, the different between an early and modern one~ the hook on the left is modern, the black one on the right, c1860(see how it is hammered flat on the edge?) If you look in the center of the modern hook on the left, you will see and added wire there, making the count 3, instead of 2....
That 3rd wire, (the modern ones are still just made from a single wire, they are just wrapped differently) is what makes the 'safety catch' on the back of the hook. Some of them have such a high bump, that they really are quite difficult to get unhooked, and when hooked into the eye, or loop, make a little 'snap' noise. You can see the early hook has an entirely FLAT back.