Soldering provides reasonably permanent but reversible connections between copper pipes in plumbing systems as well as joints in sheet metal objects such as food cans, roof flashing, rain gutters and automobile radiators. Soldering is used in plumbing, electronics, and metalwork from flashing to jewelry and musical instruments. Soldering was historically used to make jewelry, cookware and cooking tools, assembling stained glass, as well as other uses. 3000 BC were assembled using hard soldering. Soldering and brazing are thought to have originated very early in the history of metal-working, probably before 4000 BC. There is evidence that soldering was employed as early as 5,000 years ago in Mesopotamia. Origins Small figurine being created by soldering Soldering is an important skill for many industries and hobbies, and it requires a combination of technical knowledge and practical experience to achieve good results. Each method has its own advantages and disadvantages, and the choice of method depends on the application and the materials being joined. There are several methods of heating used in soldering, including soldering irons, torches, and hot air guns. Different types of solder require different temperatures to melt, and heating must be carefully controlled to avoid damaging the materials being joined or creating weak joints. In addition to the type of solder used, the temperature and method of heating also play a crucial role in the soldering process. Lead-free solder has also become more widely used in recent years due to health and environmental concerns associated with the use of lead. Common solder alloys include tin-lead, tin-silver, and tin-copper, among others. The solder used in the process can vary in composition, with different alloys used for different applications. It is also used in plumbing and metalwork, as well as in the manufacture of jewelry and other decorative items. Soldering is commonly used in the electronics industry for the manufacture and repair of printed circuit boards (PCBs) and other electronic components. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creating a strong and durable joint. Soldering ( US: / ˈ s ɒ d ər ɪ ŋ/ UK: / ˈ s oʊ l d ər ɪ ŋ/) is a process of joining two metal surfaces together using a filler metal called solder. For thermocouple contacts, see Cold junction (thermocouple). Step 5: Ready Your Components.'Cold joint' redirects here.

It gives neater results than a straight pull, because you don't have to stop midway through the pattern to re-apply paste.

It saves solder paste, by pressing what you already have down into the stencil.

Since paste tends to creep up the knife blade, this approach has two benefits: The less you pause in your sweep across, the smoother your pull will be, and the less touching up will be necessary afterward. *NB: Though the image shows a single quadrant done, I actually recommend doing a full half at a time if you can. By the end, you should be pressing solder paste down from the side of the knife into the stencil.

Start with your knife at a medium angle, about 45º, and decrease this angle as you pull across.

Pull the stencil tight across your board(s).

Put some solder paste along the edge of your putty knife, so it will move smoothly across the stencil.

Lay down a line of solder paste next to the stencil area.I like to use this method, which requires a flexible knife:

Soldering paste use