In the past, zed cards were not cheap to make, and design methodology were simple. Most runway models were short of the capital to print zed cards, so they got started with an uncomplicated 8x10, black & white glossy print with a quarter inch white edge. Stats were put on to the opposite side in plain text.
I remember those bygone days, printing a ton of copies of the same boring picture. Again and again. These 8x10 photographs were also somewhat costly, and this impeded the model giving them out. Models often sent them to businesses who were fairly likely to offer them some work, or to casting directors who were likely to give them work. Models most likely missed out on many jobs simply because they couldn't afford to distribute headshots to anyone who was interested.
With time, a model would be more successful and pocket more profit. This would make it possible for the model to print a monochrome sed card produced by an large printer. Only the most successful models in The big markets could manage to get full color. Offset printing needs a lot of money up front, but the investment became less expensive if a set of hundreds or thousands of sed cards was created. With this, a model had tons of cards in their bag - and the model could more readily afford to distribute a card to anyone who might be a little interested in interviewing the model. The composite cards were even cheap enough to use the postal service to dispatch to agencies around the world, making larger a model's market.
The composite cards of the past were a particular way as a result of the techniques and requirements involved with printing. This called for a large photo on the front and a collection of photographs, all a quarter of the available space, on the reverse of the card. A location was also held on the reverse of the composite compard to hold vital stats for the model and a method of contact.
Printing standards got in the way of the photos on the reverse of the zed card from sharing space in the slightest way, and you weren't able to include any cool backdrops or designs. All composite cards were as a result made on a simple background, with quarter inch white strokes. These strokes also let the printing press to grab the sed card as it passed through the printing process. Designers couldn't print the image to the edge, the way present day cards and set ups do. Despite the fact that printing tools has come so far, the composite cards we design in the present are still founded pretty completely on this old design, which resulted from the realities of printing.
