Sandblasting (Media Blasting) Shop Tech
Understanding the technology and equipment available
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Types of sandblasting equipment
There are two primary types of sandblasting equipment. They are differentiated by how the blasting media and
compressed are are mixed and distributed. The most common type of sandblasting equipment is siphon feed. Siphon
feed equipment utilizes a sandblasting gun as the mixing point for the media and the air. The basic manner in
which this functions is that the compressed air is passed across a supply tube that is inserted into the media
supply. As the compressed air passes over the tube it creates a vacuum effect that draws the media up into the
compressed air stream. The mixed stream of air and media is the shot out through the nozzle of the gun where it
then impacts the surface to be cleaned.
In contrast to this, the other type of equipment pressurizes a resevoir which contains the media blasting
material. In this configuration the sandblaster then uses the overall system air pressure to force the blasting
material out of the resevoir at the full speed and rate of the compressed air delivery.
Pros & Cons of Equipment Type
Siphon Feed based equipment
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It's all about the CFM baby!
The basic reality, outside of sandblasting equipment itself, is that you can only do as much as your Air Compressor
will allow for. So,
when looking into the option of doing some of your own sandblasting, ensure that you realistically assess your air compressor before even
looking at any sandblasting equipment. The critical aspects to know about your air compressor are: horsepower rating, maximum PSI rating,
volume, and CFM ratings.
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When all is said and done, the most critical rating of all is the CFM rating for the particular PSI range you're working on. You need to
ensure that it, at a minimum, matches the CFM rating necessary for the sandblasting equipment, or, preferably, exceeds it. Now, with a siphon
feed based system you can get away with running near the maximum output of your compressor, you'll simply have short durations of work, with
extended wait times for the compressor to recycle. If you're attemping to run a pressurized system, you will continually have the issue that the
system only operates at peak efficiency for the first few seconds that you run it. Anything after that and you're fighting a losing battle
of not being able to maintain enough overall pressure to continue the work.
Now, for most of us, we're not going to be doing huge blasting projets where we take down and entire frame or chassis. There's a matter of
economy on projects of that sort of scale. If you're only ever going to restore one car, then it's better to farm out the work to someone
else. But there will be times when small scale sandblasting is a good option. As long as you have an adequate sized compressor and a siphon
feed gun you're set for 90% of the smaller, simpler tasks.
When I first started sandblasting my own parts, it was on a small scale with a siphon gun and it was done out in my back yard. While this was
cheap, it wasn't easy or neat. Why is this? Well, for starters, when you're blasting out in the open there's no way to control where your blast
media goes, and proper media isn't necessarily cheap. Then I advanced to rigging lean-to structures out of spare lumber and a tarp. More efficient
because I was able to recover some of the sand, but a pain in the backside to set-up and take down each time I wanted to take care of a small
part.
Eventually I broke down and bought myself a blasting cabinet. You can get relatively small/simple ones inexpensively that will meet most needs.
No, it won't turn you into a sandblasting shop over night, but you will finally get far enough where you can maintain the equipment in your shop
and use it when needed. The things to look for in a basic blasting cabinet is how easy is it to get parts in and out of the unit, how good the
visibility is into the unit, and how well it seals. In terms of simple upgrades, a light inside the unit makes a huge difference, and most
cabinets now have clear plastic stick on shields to protect the window from abrasion. It's also a dusty, messy process. Look for a blasting cabinet
that will allow you to hook up your shop vac to help extract the ambient dust from the unit. (The dust removal also greatly aids visibility.)
In terms of use, the single best recommendation I have (short of learning how to use it appropriately) is to put on a pair of the nitrile gloves
before sticking your hands into the unit's blasting gloves. It greatly helps to minimize glove goo from sweaty dusty hands. For more information
on Blasting Cabinets (particularly DIY improvements) check out my article on Media Cabinet Modifications.
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