Sandblasting Sandblasting is a general term used to describe the act of propelling very fine bits of material at high-velocity to clean or etch a surface. Sand used to be the most commonly used material, but since the lung disease silicosis is caused by extended inhalation of the dust created by sand, other materials are now used in its place. Any small, relatively uniform particles will work, such as steel grit, copper slag , walnut shells, powdered abrasives, even bits of coconut shell. Due to the dangers of inhaling dust during the process, sandblasting is carefully controlled, using an alternate air supply, protective wear, and proper ventilation.
A sandblasting setup usually consists of three different parts: the abrasive itself, an air compressor , and a blaster nozzle. For etching and small object cleaning, a workstation to hold the piece of glass is also needed, as is some sort of collector to gather up excess dust. Sandblasting is primarily used for two somewhat different applications. The first of these is to clean a surface of anything that may be clinging to it. The second is to either etch or carve designs or words into glass or a similar material.
The first sandblasting process was patented in the US in 1870. As a cleaning method, it is often used for priming a surface for the application of paint or a sealant. When painting, one doesn't want to trap dust, dirt, or bubbles in a previous layer of paint, or other imperfections under the new layer. By launching small bits of abrasive at the surface at a high speed, all imperfections are knocked loose and can then be easily washed off, creating an incredibly smooth surface upon which to lay the new layer of paint. Sandblasting may also be used for such projects as cleaning the hulls of ships or large structures such as the Golden Gate Bridge.
In decorating glass, sandblasting is a wonderfully popular technique, with few substitutes. While hand-etching is possible, it is incredibly time consuming and expensive, and laser -etching has a range of flaws which make it a questionable choice. There are two main ways in which sandblasting is used to decorate glass: etching and carving.
In glass etching , abrasive is blasted at the glass lightly to turn the glass semi-opaque. This 'whiting' or 'snowing' of the glass can be used to great effect to produce words or images. By adjusting the speed of the sandblasting and the angle from which the abrasive is being launched, differing shades can be created, allowing for some true works of art. Glass is carved by steadily sandblasting the surface through a stencil which protects the areas you don't want to be carved out. Sandblasting as a technique for carving can be very nuanced, with differing depths and angles of cuts creating an array of lighting effects that may be quite beautiful.
The cost of sandblasting equipment depends greatly on the scope of the projects intended. A small home glass carving setup can be acquired relatively inexpensively, while a system with a cabinet capable of handling larger pieces of glass and more nuanced sandblasting can cost significantly more. A professional-level artistic sandblasting setup will likely be quite expensive. Industry-level sandblasting equipment also varies in cost, again depending on the scale and scope of the projects to be completed.
A sandblasting pot is a purpose-designed container used to hold loose, abrasive mediums used in sandblasting operations. Most are designed to be used as add-on units on existing compressed air systems allowing operators to utilize the many benefits of sandblasting without the high costs associated with installing dedicated abrasive blasting equipment. Sandblasting pots range in size from small units with internal capacities of 80 to 100 pounds (36.3 to 45.4 kilograms) for use in light industry or domestic applications to heavy industry models capable of carrying 300 pounds (136 kilograms) or more. The smaller sandblasting pot is often made of high-impact plastic with larger examples usually featuring welded steel construction. Most sandblasting pots are open at the top of the tank for filling and deliver the abrasive into the compressed air line at the bottom of the tank by means of a simple gravity feed arrangement.
Abrasive grit carried at high speed in a stream of compressed air is an extremely efficient and both cost- and labor-effective method of removing corrosion and a wide variety of finishes such as varnish and paint from metal surfaces. Sandblasting, as it is known, can also be used to strip finishes and contaminants from wood and masonry and may even be used to frost or engrave glass . One of the easiest methods of installing a sandblasting system in the home, workshop, or factory where a reliable source of compressed air is available is to purchase a sandblasting pot. Consisting of little more than an open-topped cylinder with a compressed air fitting on the bottom, a sandblasting pot is a convenient way of performing most sandblasting jobs .
A wide range of these devices are available with capacities and construction to suit most needs, from the do-it-yourself weekend warrior to the large factory owner. Small models are typically built from tough, high-impact plastic and feature capacities of around 100 pounds (45.4 kilograms). Larger, industrial varieties are usually made from plain or stainless steel, and may carry 300 pounds (136 kilograms) or more of abrasive grit. The containers are generally filled from the top and gravity feed the abrasive into the compressed air line through a opening in the bottom of the tank, with some sandblasting pot types featuring a foot switch that allows control of the flow of sand into the air stream. The gravity feed system is particularly effective as it is not prone to clogging even with damp grit mixtures.
Blast cabinets, pressure blasters, and of course sand are all sandblasting equipment used in various ways. Both blast cabinets and pressure blasters are types of sandblasters . Air compressors, yet another type of sandblasting equipment, are pieces of machinery that feed compressed air into the sandblasters to enable them to operate. While sand is not usually referred to as equipment, it is an essential part of sandblasting. In addition, it is often the most inexpensive part of sandblasting due to the insignificant price of sand in most places.
The actual sand is arguably the most important piece of sandblasting equipment. In sandblasting, sand is used as the abrasive material that is forced against other surfaces in order to affect them in different ways. Sand is essentially very small particulars of stone, though it may be composed of other mineral materials as well. This versatile material is also used in many other construction applications, such as adding texture to paint, making up a large percentage of the ingredients in concrete, as well as being the main ingredient of glass . Silcia sand, sand containing a lot of the chemical compound calledsilicon dioxide, is the type of sand most commonly used in sandblasting around the world.
Another piece of sandblasting equipment is called the blast cabinet, and it is essentially a medium-sized box that sandblasts items placed in it. A sandblasting cabinet normally has armholes in it so that the worker can put his gloved hands inside. This type of sandblasting equipment is frequently used to remove rust or other debris from automotive equipment. A dust collector either comes with this piece of equipment, or it can be purchased separately and placed on top.
A pressure sandblaster, more simply known as a pressure blaster, is typically a type of portable sandblasting equipment. It primarily consists of a tank on wheels with a hose and nozzle and is used to remove paint, rust, or graffiti from walls and other surfaces. The size, portability, and power of a pressure sandblaster can vary significantly, often with more expensive products being more effective at their job.
Air compressors, often diesel ones, are typically used to provide air to other pieces of sandblasting equipment that use it to push the abrasive material. The general purpose of an air compressor is to compress air and then express it energetically in bursts. There are many different methods that air compressors use to achieve this task, and they can use various types of fuel.
Sandblasters are devices that use sand, or a similar substance, to prepare a surface for refinishing. The sand is usually propelled from a special nozzle, often referred to as a sandblasting gun, by pressure. Three main types of sandblasters include gravity fed, siphon, and pressure blasters. They can also vary in size, from very small to very large, for every type of job.
Gravity fed sandblasters, as their name suggests, work because of gravity. Sand is placed into a small container, sometimes called a hopper, that is mounted on top of the gun. The gun is then hooked to an air compressor . When the trigger is pressed and the air blasts out of the nozzle, sand falls from the container and is blasted out of the nozzle.
When using a sandblaster, protective clothing should be worn. Eye protection, like goggles, is one of the most important things to remember when sandblasting. Sand, or other types of sandblasting media, could get into a person's eye while working and scratch the sensitive tissue on the surface of the eyeball. Other protective gear can include respirators and gloves.
Sand Blasting Procedures
Sand blasting is a common element of concrete construction and routine building maintenance. Sand blasting can be used to etch decorative patterns into freshly poured concrete and is the most efficient way of removing graffiti and other unwanted paint. Sand blasting is also great for removing rust from any metallic surface. As diverse as the uses of sand blasting are, you are essentially spraying sand at high velocity. That means there is the potential to damage surfaces if certain precautions and procedures are not followed.
Dress with Safety in Mind Sand blasting works by blowing sand out of a nozzle at high speeds. The sand is traveling fast enough to bounce off the surface, sending a combination of sand, paint and other debris in your direction. These particles will instantly become abrasive to the skin and can cause significant damage if they are inhaled.
Protective eyewear is essential. Sand can work its way into the smallest crevice, so eyewear should fit snugly against the skin. A protective filter should also be worn over the mouth and nose, although a complete respirator system would be preferred.
Coveralls are also ideal to wear, but the ankle and wrist openings should be wrapped in duct tape to prevent sand from entering the suit. A strong pair of work gloves will complete the set.
Use the Right Materials for Sand Blasting Sand blasting requires two primary ingredients: sand and compressed air. Pay close attention to each in order to do an effective job at blasting a surface. The sand should be fine and free of any debris. It helps if the sand is a uniform shape and size. There are bags of sand that is manufactured specifically for sand blasting, but a cheaper alternative is to purchase bags of sand that are intended for playground sandboxes.
The air compression is also critical. You will need a steady air pressure of at least 70 PSI to blast the sand fast enough, although 100 PSI is preferred. Most private air compressors can only run at this rate for a few minutes before they have to be turned off to recharge. Consider upgrading to a commercial air compressor for sand blasting jobs.
Drape the area with heavy tarps to recapture as much of the sand as possible. This makes it easier to clean up, and the sand can be reused once the paint and other debris have been sifted out.
Keep the Right Distance and Movement The end of the sand blaster should be held eight to 12 inches from the surface being blasted. Holding the blaster closer than this will narrow the impact field to a finer area, but it will also tear through the surface material much faster if you are not careful. It is also possible to hold the nozzle farther away. This results in the sand being distributed across a wider area, but it also means it makes more passes to remove the surface layer. It is also important to keep the sand blaster moving in a sweeping motion at all times. Holding the sand blaster steady on a fixed point can quickly eat a hole in the material.