The Hempel Group, one of the leading marine paint manufacturers in the world, has announced it will phase out during 2002 tributyl organotin (TBT)-containing paints and replace them with its Globic tin-free antifouling products in full compliance with International Maritime Organisation (IMO) requirements.

An IMO convention adopted in 2001 calls for a ban on TBT-based antifouling products, which are known to harm non-target organisms in the marine environment, and has provided dates for the ban to be effective.

Hempel said its tin-free Globic range, which used an innovative and patented technology of zinc carboxylate, provided up to 60 months of service time while offering consistent polishing rates.

"To enhance the mechanical properties of the paint an innovative use of mineral micro-fibres has been introduced, resulting in a strong yet flexible paint film.

"Added to this is the highest volume solids content of all new tin-free products in the market fulfilling new and more restrictive limitations to VOC content," said Hempel Paints Saudi Arabia national coordinator for marine coatings Michael France.

Since its initial test application in 1995 more than 625 full-ship applications were carried out using Globic by the end of 2001. The knowledge and experience gained on various types of vessels during those years had shown that the tin-free technology used by Hempel today enabled a performance similar to that offered by TBT-containing paints, without their ill effects, France said.

The IMO convention bans the application and use of TBT-based antifouling in a phased manner and imposes a number of important issues on the shipping and paint manufacturing industries. It states, among other things, that the application and use of TBT-based paint will be banned from January 1, 2003; TBT-based paints have to be either sealed or blasted off by January 1, 2008 and also that the convention enters into force 12 months after the date when 25 countries, representing s minimum 25 per cent of the world's gross tonnage, have ratified the convention.

A number of countries have already in place approval schemes whereby paint manufacturers have to submit extensive data packages both for the products and their active ingredients for their regulatory authorities to evaluate before a product can be introduced to the local market.

"Only committed companies will find themselves capable of complying with these requirements and thereby have a worldwide presence in the future," said France.

The move to tin-free products followed concerns first raised in the 1980s after deformations were observed in oyster shells and populations of certain marine snails decreased in areas adjacent to marinas, harbours and shipyards. Early reports found that increasing concentrations of TBT in the water contributed to those effects, which prompted the paint industry, among other sectors, to research and develop tin-free products.

TBT-based antifouling had served the international shipping industry for decades, the TBT copolymer efficiently serving as both polishing regulator and biocide while also contributing to protecting the environment against a substantial amount of carbon dioxide and sulphur dioxide obtained through savings in fuel consumption. In fact, the SEPE (the European Council of Paint, Printing Inks and Artists' Colours Industry) had estimated that the use of efficient antifouling paints each year prevented emission of more than 200 million tonnes of carbon dioxide and more than 5 million tonnes of sulphur dioxide into the atmosphere.

But the harmful effect on non-target organisms meant the paint industry had to search for alternative antifouling agents. They had to fulfil several requirements to have an acceptable environmental profile: high activity towards target organisms at the paint surface; low biocidal activity towards non-target organisms; rapidly degradable once released from the paint surface and a low potential for bioaccumulation in the marine environment.

The search resulted in the introduction of numerous tin-free alternatives based on different functional binder systems. These included synthetic binders of zinc acrylates, copper acrylates and silylated acrylics as well as an innovative and patented technology of zinc carboxylate used in Hempel's tin-free Globic product range.

"In summary, with the various tin-free technologies available in the market today, ship owners are encouraged to acquaint themselves with these new technologies in order to gain knowledge about the products best suited for their operational needs," said France.

"Individual companies, whether within the shipping or paint manufacturing industries, may choose to commit themselves now or comply sooner rather than later. Irrespective of which option they choose, it seems evident that it is time for a change."