In Escape from Alcatraz, Clint Eastwood plays Frank Morris a convict in the infamous maximum security island prison off San Francisco. The film is based on the true story of Morris's escape from the prison. He uses a small nail clipper to pick away the plaster / cement off his prison wall to make a hole large enough to escape through.

Morris steals a spoon from the canteen and apparently joins the handle to the end of the nail clipper to make a longer pick. He carefully removes some match heads to make up a pyrotechnic mixture. He places this in a tin can under the join of the spoon and clippers. Then he scrapes off pieces of a coin (a dime) onto the metal joint before lighting the matches. After the flare has died down and the metal has cooled he tries the joint out - it holds! So, is it feasible, could you really 'weld' the two pieces of metal together using matches?

The temperature produced by burning matches is quite high perhaps 600-800C but not nearly enough to melt steel or iron (the spoon and nail clippers)

The film is set in 1960's and before 1965 dimes were made mainly of silver (ca. 10% copper and 90% silver) which melts at a lower temperature than steel or iron. Morris chips bits of the coin onto the joint so perhaps he was using it as a silver solder. However, you need a chemical flux to get a good solder joint. When flux is heated it reacts with metal oxides reducing them to the pure metals, which helps the solder flow. You cant get a decent solder joint without it.

Our prisoner might have been able to make a flux from the cleaning chemicals he come across during his chores. Borax (sodium tetraborate) was a common detergent at the time and works as a silver flux when mixed with water.

In our TV series Hollywood Science we tried to reproduce this technique but found that the heat generated by the matches was too short lived to produce enough temperature to melt the silver solder. We even tried wrapping the joint in foil, so that the silver, flux and matches were contained together for maximum efficiency but it failed completely. I suppose it is conceivable that he could have kept adding matches to provide a continuous heating but you would have thought that, even in the middle of the night, the guards might have smelled (and seen) the smoke produced by such a fire.

Perhaps the combination of a small hole he had already made and the windy island prison location provided a suction able to extract the smoke produced by the reaction. This could have provide a flow of air over the reaction to enhance the combustion (like bellows in a furnace) and so raise the temperature to be able to solder the joint.

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