What solder resist other than rosin can I use to hand solder wires with a soldering iron without solder paste?

Organic, inorganic and resin.

Solder resist, as the name implies, is a layer that prevents soldering. It is generally green or other colors, covering the layer of film on top of the copper wires, which acts as an insulator, and prevents solder from adhering to some copper wires that do not need to be soldered. Of course, it also protects the wiring layer to some extent.

Classification of commonly used solder resist

There are many types of flux, can be broadly divided into organic, inorganic and resin three series.

Resin flux is usually extracted from the secretion of trees, belonging to the natural products, there is no corrosive, rosin is a representative of this type of flux, so it is also known as rosin type flux. Since the flux is usually used in conjunction with solder, it can be categorized into soft flux and hard flux, corresponding to the solder. Electronic product assembly and maintenance of commonly used rosin, rosin mixed flux, solder paste and hydrochloric acid and other soft flux, in different occasions should be based on different welding workpiece selection.