The theory behind keeping an arc going is, the electrical current is forced between the welding rod tip and the steel you are welding. If you want to be a successful welder you must be able to strike an arc and keep it going without even thinking about it.
The 2 most common ways of starting your arc are by tapping and scratching your welding rod to the steel. Scratching seems to be the most natural way used by beginners.
Scratching is when you swipe the rod across the steel as if you were trying to light a match. Once the rod makes contact with the steel, the arc starts. The only real reason for scratching it to get it started is so it won’t stick to the steel since it is in motion. The trick then is to locate where you want to weld and try to keep the arc going. This takes some practice to get the hang of it.
Tapping is basically stabbing the steel with your welding rod. This is better for starting your rod in the correct welding location, but it is harder to keep the rod from sticking and still maintaining an arc. The natural reaction is once the arc strikes, you will want to pull it away to keep it from sticking. The only problem is, beginners tend to pull it too far away and lose the arc. This can go on and on and is actually pretty funny to watch someone doing this. But we all need to remember we were new at one point also.
Sticking of your welding rod is caused by the rod melting to the steel before it is pulled away slightly to maintain it’s arc. I won’t go into how far away it should be from the steel since it is dependent on what type of rod you are using and the amperage you are welding with.
These are the basics and should give you an idea of how to strike an arc. Just remember that it takes practice and patience to get good at it. One day you will grab the stinger and it will all just click in your head. It will almost start to feel natural, then you will know it’s all coming together.