There are many different methods that can be used in abrasive cleaning and blasting, as the ultimate method of cleaning is to use abrasion and friction to clean a surface. However, one of the more unusual materials used for this purpose is dry ice.
Whilst dry ice, a solid form of carbon dioxide, is primarily used in food storage, flash freezing and sometimes as a theatrical effect such as in the creation of certain types of cocktails, it is also widely used in the field of industrial cleaning.
Its origins lie with the United States Navy, who first experimented with dry-ice blasting as a tool for degreasing.
The dry ice blasting method works partially in a similar principle to other forms of pressurised friction such as sandblasting, where pellets of dry ice are shot out of a pressurised air stream at a surface, providing a strong cleaning effect.
But unlike sandblasting, which has a strong abrasive effect, dry ice’s cleaning power comes from two other properties: firstly, the thermal shock of the very cold solid carbon dioxide particles (and their heat adsorption as they turn into a gas) freezes and contracts the contaminant, breaking it away from the substrate.
And secondly, the change from solid particles to a gas produces a huge volume change – explosively levering off the contaminant.
There are a lot of advantages to using dry ice as a cleaning agent, particularly for some industries such as food processing and cleaning moulding equipment. It can also be used to clean equipment without taking it apart.
Because it leaves no chemical nor abrasive residue, it is safe to use when cleaning equipment used for food. The carbon dioxide quickly converts into a gas which can be harmlessly ventilated away, unlike cleaning solutions which require the use of solvents.
The fact that dry ice is not abrasive means that it is often used to clean moulds without causing damage to them. This is something that is essential in the manufacture of precision components.
Similarly, it is often used in conservation and preservation, as it can be cleaned without causing damage through abrasion.
It does have a few disadvantages – care should be taken in a confined space – because of the danger of asphyxiation to the operator and humid atmospheres will create damp or even very wet surfaces because the dry ice will cool them