Art of glass blasting

A new grit blast medium made from 100 per cent recycled glass has proved successful as a method of cleaning steel and preparing metal ready for painting.

A full-scale test at Dunstons Ship Repairs in Hull was part of a wider series of trials commissioned and funded by WRAP (the Waste & Resources Action Programme) and managed by the Shipbuilders & Shiprepairers Association (SSA).

Carried out in controlled conditions, the trial compared the performance of recycled glass grit with copper slag, the shipyard’s usual abrasive, in blasting a mooring pontoon.

Graham Billany, Managing Director at Dunstons, said, “We’ve used copper slag for more than 30 years and while this is a cost effective material we were interested in exploring the potential of recycled glass grit as an environmentally friendly alternative.”

In the initial trials, recycled glass demonstrated improvements in productivity over the traditional copper slag of up to 240 per cent and the time taken for blasting was reduced by up to half.

In addition to representing a more sustainable use of resources, recycled glass grit’s main benefits over conventional blast media are that it is non-toxic, inert and does not cause respiratory or environmental problems. Unlike some traditional media, it does not contain crystalline silica or heavy metals and so can be used in public places and environmentally sensitive areas, such as watercourses.

In contrast to most conventional abrasives, recycled glass does not have to be imported, meaning shorter delivery times for blasting companies and potential environmental benefits, through less energy being used in transportation.

Andy Dawe, Materials Section Manager (Glass) at WRAP, said: “We’ve been aware of the advantages of recycled glass grit in the UK for some time, but our task has been to demonstrate the operational and commercial benefits to the market by funding trials such as these.

“The results of these trials will have implications for a wide range of industry sectors which use grit blasting extensively to clean, descale, deburr and remove surface contaminants.”

The widespread use of recycled glass will assist the UK in meeting its target under the European Union packaging directive, which says 60 per cent of glass must be recycled by 2008. Preliminary data for 2005 indicates that 50 per cent was achieved.