Wednesday, 13 August 2014

Silver - more valuable than you think

Elizabeth Henderson
Product Development Manager

Silver was formerly seen every day in our pockets – although it has been superseded in British coins it still works in many other contexts. Its ductility and malleability means it has been used since ancient times to make jewellery, ornaments and luxury items. At Itac we exploit its properties as a biocide – silver ions when in contact with bacterial DNA prevent its replication and appear to do this by interrupting the S-S bonds in the molecule. We can incorporate small amounts of silver containing compounds in coatings to exploit this effect. Silver nitrate in a block or as a solution was applied to skin infections to kill the bacteria in the nineteenth century, but in the twenty-first silver nanoparticles have been developed for use in textile medical dressings.
In other parts of the chemical industry, silver has been used as a catalyst for production of ethylene oxide and formaldehyde, particularly for ethylene oxide which is used as a building block for polyesters (step to polyurethanes). Itac uses these catalysts indirectly as we use a number of polyester PUs in our products for textiles.
The photosensitivity of silver was exploited to make pictures from early developments in the 1830s until the present day, although its use diminishes as digital photography improves. Colourless silver ions are reduced to black particles of silver metal by visible light, and will form a ‘shadow’ of a pattern placed between the silver ions and a light source. Over this time, the technology for using silver was refined from silver nitrate solution on a glass plate to emulsions of silver nitrate in gelatine on a flexible film.
Silver-containing materials also play a major role in everyday electrical items due to its excellent conductivity. Inks formulated with silver are used to produce printed circuit boards and other items such as contact films beneath computer keyboards. The heating elements on car rear windows are made of silver-based ink to conduct both electricity and heat across the glass.