I am having coffee--- the fru fru kind with flavored creamer. Boy its good, but I was thinking at the same time. I know -- I know, its a bit much to think and drink at the same time, but I did it. I was thinking about strings, wires. A lot of artists do not string their work. I don't know if it is a lack of knowledge or if it is laziness. I can tell you right now that if you submit works to galleries, they will not hang it if it doesn't have proper hardware. And why should they... It could fall on someone.
Here is a little video showing how to add wire to your picture. It is the same for a painting. You want to make sure that the wire that you use works for the size of your painting. For example wires have different strength. They show on the box how many pounds they hold. So if you have a painting that weighs 20 lbs you want to get at least a 30lb wire. I always go over. I may even go toward a 40lb wire. Next you want to measure your piece in thirds. You will screw in your clasps 1/3 of the way down on your painting. That means if your painting is 30 inches you will put your clasps at 10 inches. The reason for doing this is to keep all the wires on the back at the same level. Now here is the caveat to that-- even if you do this they will not end up the same because of the different slack in the wires. It is pretty improbable to get all the wire taught to the same specs. But I digress. It is better for the clasps to be even.