First, find an electric iron. Then, overlap the two plastic films that you want to connect together. The overlap width is the same as the width of the electric iron (referring to the heating width of the bottom of the electric iron), or both are wider. This will be stronger. After overlapping, stick a layer of hard paper on it. When the electric iron is hot, press it directly on the paper. In this way, the plastic films will stick together. Sometimes the paper will stick together, but it doesn't matter, you don't have to get it.

If the actual operation, it is best to find an expensive exercise first, and then carry out the actual welding after the technology is successful. In addition, the plastic film is preferably thick. I remember there is a kind of mould called the ground mould, which is so thin that it can't be heated and welded. But usually the greenhouse film is thick, because it is used to keep warm from the wind.

You can send it if you don't understand it. I will give it to you.