Why can't I get solder to stick to my rails?

Most modellers will not dispute that soldering dropper wires to your tracks makes for the best electrical continuity around a layout, but, soldering wires to rails can often be more difficult than imagined and getting the solder to adhere to the rail can be a bit of a pain.

Too often when soldering dropper wires to rails, what started as a simple job ends with blobs of solder lying on (but not actually attached to) the metal rails, while infuriatingly, sleepers many centimetres away are reduced to a smoking mess of molten plastic.

The likely cause of this all too common occurrence is a lack of power in your soldering iron. If your iron is not powerful enough to heat the rail quickly, heat generated will escape along the rail before it warms enough to melt the solder into a free-flowing liquid hence the blobs. The escaped heat will, however, be more than enough to ruin any plastic parts or worse fine electronic components nearby.

Another common cause of solder not adhering to rails is a dirty surface. Although a rail may look and feel clean, there's a high chance there will be the presence of oil, grease or dust that you can't detect with the naked eye. A light sanding of the surface to be soldered (including wires) should be enough to remove any annoying pollutants that would otherwise cause your join to fail.

Soldering well requires not only the right tools for the job but also experience. If you are new to soldering a top tip would be to practice on an offcut of track and a spare bit of wire. Try a few techniques to perfect transferring heat quickly from iron to track and compare the difference between soldering to dirty metal and a well prepared surface, before you know it you'll be dropping in dropper wires quicker than you can say 'electrical continuity'.