When you’ve been in the business of media blasting and painting for nearly 30 years, you tend to pick up a few ideas and tips that make life a little easier. For Jim Deardorff, who owns and operates Superior Coatings in Chillicothe, Missouri, those shortcuts can also mean a little more money in his pocket, since time literally is money in his business. 

Over the years, Deardorff has media-blasted everything from classic cars and tractors to wrought iron lawn furniture and metal buildings. A few years ago, he even media-blasted and repainted a fighter jet that is on static display at the Chillicothe airport. 

In the process of continually seeking new answers, he’s developed his own media mix and process, called Classic Blast (classicblast.com). It consists of a low-pressure cleaning process that uses a unique blend of fine, dense aluminum oxide, trace minerals, and graded walnut shells.

Here are just a few of the tips Deardorff has discovered over the years that will help anyone facing a blasting job, whether it’s a classic tractor or a fighter jet.

Preparation Is Crucial Power-wash the area you are media-blasting to remove surface contamination. Washing can reduce blasting time up to 50% when grease and oil residue are present on the surface. Salt contamination (chlorides, sulfates, and nitrates) can be equally detrimental. If salts are not removed prior to painting, loss of paint adhesion can occur. 

Decals, tape, and stickers may also require more time, and it will waste abrasives if they’re not removed ahead of time. The removal of these items with blasting can take up to 10 times more effort than the removal of paint.

A simple way to check paint toughness is to take a pocketknife and scrape across the paint. If you can scrape down to bare metal in one light pass, then the paint will probably blast off easily. If it takes two or more hard scrapes to get down to bare metal, plan on more time and more abrasive material or a heavier abrasive to finish the job.

To protect bolt threads, acquire some clear plastic tubing the same inside diameter as the bolt, and then simply slide it over the bolt.   

For blasting loose nuts and bolts, locate a 2×4 or 1×4 and drill holes that match the size of the bolts. Insert the bolts through the holes and attach the nuts on the other side. This will protect the bolt threads, while allowing you to clean both the bolt head and the nut. 

To keep blasting abrasives out of holes, cracks, and cavities, keep an assortment of plugs and threaded bolts on hand that can be used to plug holes in the engine, transmission, brakes, and bearings. Be sure you remove all grease and oil residue beforehand since it’s easy to miss a hole under the grease buildup. 

Equipment Needed Turn the blast nozzle a quarter turn at least once a week with continual use or at regular hourly intervals with occasional use to provide uniform wear on the internal lining.  

When buying a new nozzle, locate or purchase a drill bit or wooden dowel that is exactly the same diameter as the nozzle lining.  Then use it to check the nozzle regularly for excessive wear, which might indicate the need for replacement. Wear can result in a loss of air pressure and a decrease in cleaning performance. For every pound of air loss, there is a 1% to 1.5% loss in cleaning production.  Abrasive waste due to a worn nozzle can also add up quickly. In some cases, the price of a new nozzle can be made up in a single week through the elimination of abrasive wastes.

Don’t throw away worn-out blast nozzles; they can be useful for brush-off blasting of steel and concrete, as well as other nonconventional applications. 

Blasting Techniques The position of the material blast hose in relation to your body can be very important to efficiency, comfort, and safety. There is a considerable amount of back pressure from the blast hose when using 100-psi air pressure. 

For ground blasting, hold the blast hose against your body using your body weight to absorb the force of air pressure. This can be done by placing the hose in front of your body or over your shoulder. In some cases, it may be necessary to have an additional worker behind you to help move and control the hose.

For high-pressure abrasive blasting (100 psi or more), it is recommended that the nozzle be positioned 90° to the work surface. This allows the abrasive to impact the surface and to produce a clean anchor pattern (profile). The surface profile resembles a mountain range under magnification with many peaks and valleys.  

When blasting small parts, it helps to work on a table that is a little lower than waist high.  Place the item to be cleaned in the middle of the table and start by blasting the area that is facing you. When that surface area is done, move the part (usually a quarter turn) to expose a new surface area. Repeat this operation until all surfaces are cleaned. Most three-dimensional parts will require at least eight moves to complete. This also helps reduce back fatigue.

Instead of trying to pour material from a 50- or 80-pound bag of abrasive into the blast pot, pour the media into a 5-gallon bucket, which is easier to handle. 

Small Parts and Rims If you have a number of small parts to handle, consider building a stand with a mesh bottom. Deardorff bought some used grocery shelving at a local auction that he uses to support small parts being blasted.   

Another option for small parts is to keep several pairs of locking pliers on hand. Attach the pliers to the part as a handle. Deardorff also uses a short piece of pipe welded to a flat base to hold the pliers while blasting. It will be necessary, of course, to reposition the tool to clean the area that was shielded.

When cleaning small wheel rims, lay one rim flat on the worktable. Then, place the other rim upright on the first rim and blast one side at a time. When a section is done, just spin the rim you’re working on with your free hand until the complete rim is finished.

For larger rims, place a 2×6-inch or 2×12-inch board in front of your worktable. Lean the rim up against the table with the wheel sitting on the board, much like a wheel sits on a rail. Next, roll the rim down the board, blasting the area at the bottom of the rim. To finish one side, turn the rim 180° and blast the other side. 

Mixing one mesh size or type of abrasive with another will often provide improved blasting performance in certain types of applications.

For example, when dealing with heavy rust or mil scale, expendable abrasives with a large mesh size can be used to break apart the heavy material. An abrasive with a smaller mesh size added to the mixture will further clean the metal profile.  

Empty the blast pot when you’re finished with a job. A small amount of abrasives in the bottom of the blast pot can draw moisture, which can also freeze in cold weather. 

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