Thoroughly clean the surfaces to be joined by using a wire brush or emery paper to remove scale, old paint or corrosion and by using white spirit or paraffin to remove oil and grease. Cover the clean joint with flux and heat it until it reaches a temperature slightly above the melting point of the solder being used. Apply flux. When the solder is now applied it should melt immediately and run into the joint. If the solder does not run freely, the joint is probably too cool and needs further heating. Solder will not run freely on dirty surfaces.
Remove the heat source and allow the joint to cool. As the joint cools, the molten solder solidifies and forms a solid joint. Do not disturb it until the solder has properly solidified – well after the solder loses its shine – otherwise a poor joint could result.
When using a soldering iron as a heal source, it should be tinned before use for the first time (and again when it gets dirty) and it is advisable to tin both parts of the joint too. To do this, clean up the bit by filing it to reveal bright clean metal. Warm it a little and dip it in flux. Then warm up the iron and spread solder over the surface. Keep the bit clean and tinned by wiping it occasionally on a damp rag when it is hot. Do not knock electric soldering irons to remove excess solder from the bit.
To tin the parts of a joint, clean them as before try not to touch them and put flux on at once. Heat up a tinned soldering iron, hold it against one piece of the joint area and rub it around so that the whole area reaches the required temperature. Put a dab of solder on the tip of the iron and spread it thinly over the joint surface. Wipe off any blobs of solder and make sure that the area is clean and evenly covered. Repeat this on the other part of the joint, bring the two parts together with a little flux in between and use the soldering iron to reheat the whole joint until the solder melts together and makes a joint. It may be necessary to add a little extra solder to the joint not to the iron.
