In addition to my hobby of tube based equipment my work is in solid state through hole and surface mount electronics. With that I use a great deal of .31 diameter solder. I use a hand held dispenser that is much easier to handle and work with than playing with lengths of it pulled off the spool. I use a BIC stic type pen to make it. I get a piece of stiff wire, withdraw the ink tube and tip frpm the outer sleeve and separate the ink tube from the tip t tear and roll up a tiny wad of tissue or paper towel and push it through the ink tube over a lined waste basket to drive out the ink a couple more wads moistened with alcohol will clean it nicely. I pull out the metal tip from the plastic tip body and put that in a prescription bottle 1/3 full of alcohol and shake it to dissolve the ink in the tip. Repeat until it all is dissolved away. I recommend gloves for the inky parts.
Then, take about 12 or 13 ft. of solder and run it through the ink tube til about 2 inches shows our rhe other end. take the long end of the solder and start wrapping it around the ink tube tightly until the coils cover the tube. then take the coils and carefully loosen them til the tube passes freely inside them. put the plastic tip back on the tube so the solder passes through it too, if the coils are too long to clear the rear of the tip, cut a few coils off. put the assembly back into the outer sleeve and just draw the solder out the tip. if it is hard to pull loosen the coils more.[You must be registered and logged in to see this image.][You must be registered and logged in to see this image.]
"Any sufficiently advanced technology is indistinguishable from magic."
— Arthur C. Clarke