DIY solder

[pyrobrewer280]

It is not hard to make your own solder. Solder is just a mixture of metals with a lower melting point (a eutectic alloy) then the metals to be joined. Start by melting the highest melting point metal and adding the next lowest metal and so on.You can use powdered borax as a passive flux to exclude oxygen and remove impurities and it forms a glass containing these impurities. Pour the molten metal from a height into a bucket of water to make granules. Stick these granules onto the joint with flux and affect the joint . The more copper / silver in the alloy the higher its melting point and the stronger the joint.

Flux can aslo be made from powdered borax it can be made into a paste with ethanol and will disolve in methanol (Finally a use for fore shots)dont use water(cant remember why)
Zinc apart, from its toxicity, is not recommended as it has a low boiling point 907C and will oxidise if over heated in plumes of white Zinc oxide smoke (Familiar if you have ever welded Gal ).
The solder is drawn into the joint by capillary action. the solder will "follow" the heat move the flame around the joint and it will flow like water. The joints should idealy be tight fitting as solders dont usualy make good fillers If you dont happen to have a crucible handy you can use a piece of charcoal dished out this works well as the carbon reacts with any oxygen in the mix removing if from the copper as co2, the borax glass prevents more oxidising. Make sure you use a reducing flame as you dont want to pump in extra O2.

Copper can be found easily without much trouble (copper coins are a mixture of nickel and copper)

Fine silver granules (99.999%) can be purchased from a bullion dealer or Jewellers supply store. Silver and is surprisingly cheap. If you have some old stirling silver(925 hallmark) jewellery / cutlery around it is 92.5% silver and 7.5% copper.

Some non ferros scrap merchants keep tin or you can use the 2 % silver 98% tin solder (If you want to make a higher strength solder)
Melting Points

Copper 1083C
Tin 231.9C
Silver 961.93C
Zinc 419.58C

Unless you have the ingredients and equipment to hand, or have a real DIY fettish and realy need to know whats in your solder, it is way easier to buy it.