Dry ice Blasting has long been considered third choice behind water and grit blasters when it comes to removing graffiti from surfaces. This is mainly due to costs and we accept that we cant compete on this particular playing field.
Weathered Steel is one surface, however, where dry ice blasting has become a viable option for removal and after carrying out recent trials, Optimum now has a full understanding as to why.
The idea of weathered steel is to save massive costs in the upkeep of structures whilst still offering an aesthetically pleasing design. The copper colouring of the surface patina gives a rich glow to structures and architects, the world over, use it.
The big problem arises when having to clean the steel. Most traditional methods (sand, grit blasting or chemical removal) actually destroy the patina, taking the light rust away and exposing the smooth steel underneath. The patina can't 'grow' back in these places and so a non-uniform, blotchy appearance occurs.
Dry Ice Blasting, however, is the perfect solution. The non-abrasive, non-grinding effect of the cryogenic, thermal explosion, means that the paint/contaminant can be removed without destroying the patina and thus maintaining the uniform appearance throughout the structure.
It is so successful that a white paper has been written on the process and was commissioned when a graffiti removal programme had to be implemented on Chicago’s iconic Time Life Building. The paper can be read here.
Our own tests also proved to be a great success and a full report can be requested by contacting Optimum directly and a short video of the trial can be seen here -
We would like to thank Make Architects and Severfield Watson Structures Ltd for their input and participation in this trial.
By Ian Reynolds