An introduction to blast cleaning

Page 1: Blast cleaning techniques
Page 2: Blast cleaning applications

Hannah Shanks - Editor

Applications

Graffiti Removal
Graffiti is a criminal activity and is often seen as a symptom of urban decay and inner city crime. Although various councils are trying to legitimise it by providing legitimate areas and presenting it in a more positive light, no one is going to be impressed by a property that appears to have been vandalised. Depending on the size of the piece that is to be removed and the paint used, it may be possible to completely remove any signs of it using grit blasting or pressure washing alone or in conjunction with some type of chemical treatment.

Decoration
Fine sand can be used with relatively low pressures to etch images or designs onto glass. This can be done free-hand but the best results are achieved by using a vinyl template. Applied subtly, attractive and stylish effects can be created using this technique and can be used to give a focal point to door windows, mirrors and panels.

When building an extension directly onto a property that is more than ten years old, one of the most difficult tasks is matching the texture and colour of the new brickwork with that of the old. If done poorly the new building can look almost unsightly and even lower the value of the house. With very old stone that has been severely weathered and may have come from a unique source, this process of matching becomes even more difficult. Grit blasting can be used very cleverly to create an artificially weathered or aged look to the new stone and when done in direct comparison to the original building, can mask the evidence that the property has recently been extended. The most successful results are achieved when the old brick is treated at the same time so that both surfaces can be brought to the same shade and hue.

Cleaning
Work on small items such as light fittings or metalwork can be done in blast cabinets. These contain the debris created by the cleaning and used more expensive media (such as glass bead, alumina or chilled iron) to blast the surface. A filtering system can be put in place to separate the particles so the blast media can be reused to reduce cost. Such machines are extremely expensive pieces of equipment and require training and practice to achieve good results and so are not usually available for hire. A workshop will more commonly carry out the work for you.

Before embarking on a large cleaning job, it is worth exploring the alternatives (chemical methods etc) to ensure that this method is the most suitable. Small aluminium units can be hired, although without the correct training these are likely to cause more harm than good. They usually weigh around 15 kilograms without substrate and are worn on the back, so require a good level of physical strength for their operation. Companies which hire equipment should be able to offer training and advice themselves or recommend a training company.

Interior work must be carried out with proper ventilation and ideally some sort of extractor fan to remove any circulating particles that may cause potential harm. Full face masks and protective clothing should be worn and the area should be assessed to ensure that it is in a safe and habitable state.

Some important questions to ask

Is a prior visit required before the work can be carried out? A company that says no may not be entirely reliable. If it is a small job that can easily be described on the phone or by emailing a few pictures only one visit may be required, but larger jobs need to be properly assessed before they are undertaken. The surface type, nature of material that is to be removed and extent of cleaning all need to be carefully assessed before work is undertaken and any company that is prepared to just turn up and have a go without the correct preparation are not likely to carry out work to the highest standard. Issues of access and surrounding surfaces and conditions also need to be considered so the work can be carried out safely and in a contained manner and to carry out the associated risk assessment. The available power sources also need to be looked at, as a source of compressed air will also be needed but this is unlikely to be available at most residential addresses. If the required power supply is not available a generator or converter may also need to be used.

Are all employees competent at using the equipment? It is very important that the people who you are paying to carry out any work are fully trained, and a good company will be able to provide training certificates or diplomas to prove this fact.

What is the company history and background? Before parting with any deposit money you should have gained enough information about the company to be fully confident in the service you will require. Details about how long they have been in business, the location of the office or primary business address and the size and nature of the business are good pieces of information to acquire. Some details regarding the size and type of previous work they have carried out is also very important. A good company should be able to provide details and pictures (a very good one may even show you the site and work itself) and references.

In addition, hire companies who you have not previously dealt with should ask you for several forms of identification and company letterhead in order to protect themselves. Failure to do this could be a sign of inexperience or unprofessional manner. Either way they may not be the best people to entrust a large job or sum of money to.

 
 


Property pros