How can a sandblasting and coating specialist be of help to me?
It’s not uncommon for householders to leave their outdoor furniture outside throughout the year. Let’s assume that your outdoor custom-made metal braai and ornate wrought-iron benches have spent a few winters outside in the elements because you did not have the room to bring them indoors. Now that summer is finally on its way, you are starting to gear up for the weekend outdoor lifestyle which is such a South African tradition, and you are keen to get everything ready for the fun. Instead of finding your braai and benches just needing a quick clean, you are disconcerted to find them with rust spots bubbling the smooth surface and the paint beginning to peel from your benches. Your prized swimming pool is also looking grubby and unappealing. This is NOT a quick clean, and you know that it will take days of back-breaking sanding, preparation and painting to get them back into pristine condition, and it is time which you simply do not have available. What can you do? Call in the sandblasting and coating specialists to sort the matter out quickly and efficiently.
What exactly is sandblasting?
Sandblasting - or abrasive blasting - is the process of cleaning, shaping and smoothing various hard surfaces by forcibly propelling a stream of abrasive material across surfaces at high speeds using compressed air or pressurised liquid, depending on the application. One could say that it is similar to a moving high velocity and very flexible wall of sandpaper but provides a more even finish. Sandblasting is easily able to remove dirt, corrosion, paint, rust and residue from oxidation, even in hard-to-reach areas which otherwise would require hours of extremely finicky hand-work. Materials which can be sandblasted include glass, stone, metal, wood, plastic, steel, aluminium, brass and silver.
Is sandblasting done on site?
On-site sandblasting is often seen in shipyards, steel construction, power stations, oil refineries, silos, and offshore oil rigs, and also in blasting yards themselves. Smaller, more portable and intricate items can be worked on in a sandblasting cabinet designed to protect the user’s eyes, face and hands when working. In these cabinets air and sand are mixed and then travel through a hand-held nozzle to direct the particles towards the work surface or work piece.
Is sandblasting a new innovation?
Sandblasting can occur naturally, usually as a result of particles blown by wind causing aeolian erosion, or artificially, as mentioned above. As a cleaning method, sandblasting has been widely used for approximately a hundred and fifty years, so it has been around for a long time, being patented by an American, Benjamin Chew Tilghman, on 18 October 1870.
Sandblasting is a versatile process
Sandblasting is extremely versatile in that it can either smooth a rough surface, roughen a smooth surface and remove surface contaminants. Sandblasting itself has several different processes under its umbrella, such as bead blasting, soda blasting and shot blasting.
There are two types of sandblasting processes, being :
- Water -Driven, used mainly for reducing surface deterioration on brick or concrete surface preparation. Hot water and soap may be simultaneously incorporated to help clean greasy surfaces during the blasting process.
- Air-Driven, best suited for metal surfaces where moisture buildup and water intrusion are to be kept to the minimum to avoid rust.
What type of abrasive media do you use for sandblasting?
- silica sand or silicon dioxide, as well as silicon carbide grit or carborundum, were originally the most commonly used media due to the fact that sand particles are almost the same size with sharp edges, as well as being the hardest blasting medium available, making it extremely effective in abrasive blasting. Still used for etching stones and glass engraving. However, due to the fact that exposure to silica or crystalline silica, as well as the difficulty in controlling exposure thereto, can lead to silicosis and a range of other illnesses, the use of this abrasive was prohibited in Great Britain in 1950 and in other European countries such as Germany, Belgium, Russia, Sweden and the United Kingdom in the late 1960’s. Silica sand is still commonly used in countries which have not banned its usage. Using beach or play sand is also not advisable as sand produces free silica. Sand also breaks up quickly, creating large quantities of dust;
- white aluminium oxide, which lasts 30 to 40 times longer than sand. This is a sharp, durable and reusable abrasive that cleans and penetrates metal. Often used by technicians to prepare a metal surface for painting;
- aluminium oxide grit, which is a standard blasting media used for grinding, polishing, surface cleaning and surface coating preparation;
magnesium sulphate (kieserite);
- plastic pellets and recycled plastic grit;
- industrial garnet, whilst being more expensive, has no safety hazards associated with ingesting the dust;
- glass beads. Glass beads are used to clean calcium deposits from pool tiles or any other surfaces, remove embedded fungus, and brighten grout colour without causing damage. Glass beads are a reusable medium that is both lead- and silica-free, used to clean and polish metal without causing dimensional changes, so often are often used in auto body work to remove paint, and to create a uniform surface on machined parts.
This medium is used on metals such as stainless steel, aluminium and brass in order to clean and polish softer metals which would not be able to withstand normal sand or shotblasting without resulting damage;
- crushed glass grit. This abrasive medium is made from recycled glass bottles. It is used to remove coatings such as coal tar, epoxy, paint, vinyl and polyurea from objects. Crushed glass blasting is best used on car bodies, motorcycle rims, engine blocks, wood and any other surface which would otherwise be damaged by conventional shotblasting;
ceramic grit or shot;
- pumice, originating from lightweight volcanic rocks, this is an ideal medium for less aggressive operations;
- acrylic grit, which is a more gentle abrasive used when stripping sensitive surfaces;
- walnut shells or fruit kernels. These materials clean and polish without damage such as marring, scratching or etching. They are both safe to use and recyclable. These are often used in agricultural applications and to prevent damage to the underlying material when cleaning brick or stone;
- corncob grit. Corncobs are used to create a reusable, biodegradable, organic medium which are ideal for cleaning and removing surface contaminants;
platinum slag is also recommended as it has sharp angular particles and is resistant to impact fracture;
- other process byproducts, for example : copper slag, nickel slag and coal slag;
- metallic: steel shot, steel grit, stainless steel shot, cut wire, copper shot, aluminum shot, zinc shot. Steel grit, in particular, is used when aggressive cleaning is needed on steel or foundry metals, and is also used when preparing metal surfaces for coating. Fine steel shot uses a process called shotblasting on mild steel, copper and brass and leaves a clean profile. This is the most efficient way to remove any old paint, rust or mill scale.
All of the above media come in different sized particles, ranging from fine to rough, to ensure a good surface for the coating to adhere to and, apart from sand, have a very low dust content.
After sandblasting metal, what else must be done?
Once metals have been stripped down to their bare basics, it is important to quickly prime and add a protective coating to prevent rust, which will rapidly take hold in humid conditions. The coating is often a paint specifically designed for metal with a rust inhibitor or repellent, but it may well often be done through a specialised process called powder coating. Alternatively, a polyurea spray coating may be applied, which is aimed at preventing corrosion, providing a waterproof lining to pipes, tanks, roofs, etc. Polyurea coatings are also abrasion resistant and protect against impact damage.
What is powder coating?
Powder coating involves spraying a fine electrostatically charged plastic powder onto the metal surface, which must be able to hold an electrostatic charge, and then baking this in a special oven at very high temperatures, which melts the powder onto the metal and creates a beautiful smooth finish. Because of the high temperatures involved in this ‘curing’ period, not all items can be subjected to this process – for instance, any metal items which are coated with or contain plastic, resin or rubber. Metals which achieve good results from this process are : aluminium, stainless steel, mild steel, galvanised steel, electroplated steel, steel alloys and iron.
What is best – powder-coating or painting?
For the purposes of durability, powder coating is not always recommended over paint for furniture and articles which are intended for year-round use outdoors. If the powder coating is damaged or begins to wear, the article has to be stripped and cleaned and the whole coating process has to be repeated, which means that the item/s involved must be portable enough to be taken to the curing ovens which are not removable from their premises. Powder coating’s strength lies in its resistance to cracking, chipping, abrasion, peeling, rust and chemical exposure damage. It is highly durable, maintains its colour and gloss, provides a uniform finish, withstands UV rays excellently and is more environmentally friendly than traditional liquid paint. Therefore, it is excellent for items such as tables, chairs, bikes, and other movable items, but not such a great choice for permanent fencing, for instance.
How to find the right sandblasting and coating specialist for your needs
Check their online ratings and customer reviews
A steadily increasing number of these specialists are becoming visible through internet searches, with many having their own interactive websites. If you are looking online, search sites such as Uptasker are great time-saving resources, and Uptasker has the added advantage of listing in geographical areas which makes it easier to find a specialist in your part of the country. Uptasker also provides online ratings and customer reviews which make it so much easier to judge service and quality satisfaction levels from previous customers. A great time-saving feature is the ability to request various online quotes from different suppliers – all without leaving your house or having them call on you if time is a problem for you.
If you prefer, you can also check for advertisements in building, house and home magazines and catalogues, visit home expos, ask building contractors, or check the Yellow Pages and newspapers for these specialists. Alternatively, you might be lucky enough to have friends who have used one of these specialists with good results, and you can find your supplier in this way.
