During fabrication, jewellers have to use a solder, or an alloy of metals like gold, silver, copper and zinc, among others. The solder melts before the gold does and helps fuse together the bits and pieces of the design.
However, the goldsmiths say, traditional solders can no longer be used if a hallmark is required, since the metals become part of the jewellery and reduce the gold content.
The goldsmiths say that they are being compelled to use cadmium solders, since this metal evaporates easily. But cadmium vapour reacts with air to form poisonous cadmium oxide.
To qualify for a hallmark or a stamp specifying the purity of the gold ornament, at, say, 22 carat, the gold content has to be at least 91.66 per cent. The hallmark ensures that a buyer of a 22-carat piece can demand payment for 22 carat when he sells it.
Generally, the traditional way of soldering or brazing reduces gold quantity by about 2 carats due to the addition of brazing materials in them.
The Bureau of Indian Standards (BIS) specifications for gold solders were modified in 1981 to specifically rule out the use of cadmium. Cadmium has a low melting point of 321 degree C and boiling point of 767 degree C, against 22ct golds melting range of 995-1020 degree C.
Now, the renewed use of cadmium has created a strong resentment among gold workers, who are poorly paid and already suffer from ill health because of having to work amidst fumes.
The goldsmiths organisation has quoted from the handbook of the World Gold Council to back its claim that cadmium is a dangerous element to work with.
The general secretary of the West Bengal Gold and Silver Industries Association, Mr Dulal Roy, said the use of cadmium in gold brazing could lead to various diseases such as cancer, osteoporosis, anaemia and emphysema.
According to Mr Roy, a gold artisan working with cadmium solder has to be exposed to the harmful fumes for the three to seven days that it takes to complete a piece.
We are ready to give 22 carat after finishing the gold in the traditional pin-soldering method, but, in that case, the loss of two carats should be compensated by way of increasing making charges, he said.
The BIS, however, maintains that its standards specifically call for the use of cadmium-free solders.
BIS officials could not comment on the soldering requirements created by the hallmarking process.
The director and head of the BIS office in Kolkata, Mr S Sengupta, said: Solders to be used for the manufacture of gold jewellery shall be free from cadmium.
Mr Sengupta was referring to IS 3095:1999, Gold solders for use in manufacture of jewellery (second revision), which lays down the requirements for gold solders used in gold jewellery/ artefacts of 23, 22, 21, 18, 14 and nine carats.
The foreword notes: This standard was earlier published in 1965 and subsequently revised in 1981. In this revision the use of cadmium has been dispensed with because of its toxicity to human organs.
This change is in line with national health requirements, international practices as well as requirements of jewellery exporters, the foreword notes.
However, the BIS has also pointed out that there is no international standard for solders for use in manufacture of gold jewellery.
A leading manufacturer and exporter of gold jewellery dismissed the claims of goldsmiths that they have to use cadmium. He claimed that what the goldsmiths are actually using is an alloy containing zinc.
Instead of the traditional solder of gold, copper and silver,we are now using a solder containing the same amount of gold, but less copper and silver and some zinc, he said.