Etch Masters: Time Equals Money: The Opportunity To Do Something: Part II

With over 35 years in the glass business, Ruth Dobbins offers experience in fused and cast glass, as well as in glass-etching techniques. Ruth holds a Master's Degree in Printmaking and Art History and has been a partner in a stained and fused glass wholesale supply company in Europe, which also placed great emphasis on a training program. For the past 20 years, she collaborated with her husband Norm Dobbins in commission work, writing books and creating videotapes on how-to techniques for glass etching. Ruth taught these techniques for 30 years in the U.S. and other countries. Ruth continues these venues by offering a complete training program at Aliento School in Santa Fe, New Mexico, and by teaching at various trade shows, including The Awards & Engraving Show. One-on-one training and consulting services are also offered. You can reach Ruth by email at, by phone at 505-473-9203 and by fax at 505-473-9218. Check out the website at

Well, here we are, finding ourselves at the beginning of another year. Did you make your New Year’s resolutions? Good, I hope that taking care of yourself, your equipment and workplace are part of those resolutions. And, just to make sure that you are not forgetting anything, I will continue with my overview of all the things I see around our shop that need attention. This way you can compare notes with me.


Well, here we are, finding ourselves at the beginning of another year. Did you make your New Year’s resolutions? Good, I hope that taking care of yourself, your equipment and workplace are part of those resolutions. And, just to make sure that you are not forgetting anything, I will continue with my overview of all the things I see around our shop that need attention. This way you can compare notes with me.


Right off the bat, I have to begin with an addendum to the previous article in regards to the compressor maintenance. One of the other things to check for safety is the shroud, or cage, that covers the belts on most common compressors. You need to consider this if you are the do-it-yourself-fix-it type. Often, when the belts need tightening or replacing, you’ll take the shroud off to access the belts. Once it is off, it often appears to be too much hassle to put it back on. Don’t mess with Murphy’s Law; don’t go there! This creates a very hazardous situation, and it is a reason why insurance companies do not like belt-drive compressors but prefer the direct drive versions.

If you move around your compressor without a shroud, you open yourself up to the possibility of catching your shirt or hair when the motor kicks in and the belts start turning. Always put the shroud back on yourself, or check it after a maintenance person has worked on the compressor. Whew, I do feel better now having remembered this!


Continuing with the equipment maintenance, I am waffling a bit as to which to cover next. I want to say the blaster is next, but immediately a possible confusion arises. Often we find that in speaking of the blaster, a lot of you think about the cabinet. In the past, this was, of course, completely wrong, since the cabinet was solely the container to be blasted in and to contain the spent abrasive. Nowadays, it is plausible that you may think of the cabinet as the blaster, since during the past several years a new category of blasting units has sprung up: the cabinet with the blaster attached to the hopper. But sorry, that excuse won’t fly: the blaster is still the pressure pot attached to the bottom of the cabinet.

In most of our shop equipment set-ups, the pressure pot or blaster is a freestanding, totally separate unit; only a couple of cabinets have the blaster attached. Now that we have untangled that confusion, I guess I will talk about the blaster next.

Attached or not, there are mostly common features to check and maintain. To be specific, I want to say that we are solely talking about pressure blasters here. There is only one other type of blaster, which is the siphon blaster. By its very nature, it is a very inefficient blaster, and most serious blasters on glass or stone would not consider using one. The comparison between the two types would be a totally separate discussion, maybe some other time. So, blasters it is.


There are several things to check regularly on a blaster that may prevent down time in the most inopportune moments. Remember Murphy? One of his rules is that equipment always breaks down close to or on weekends when you don’t have spare parts, your supplier is closed and your Monday deadline is looming.

First, your pressure pot blaster is connected to the compressor by means of an air hose in most cases. In high humidity areas, you may have hardpiped your airway to control moisture buildup. Check this air hose on a regular basis as well as the fittings that connect the air hose to your blaster.

Air leaks at fittings and holes in the hosewill cause you to lose pressure, and when the hose blows out with a considerable noise, it willprobably scare you enough to drop your glass piece in the cabinet and break or chip it. When you detect a hole in the hose close to either the blaster or the compressor, you can cut a piece off (unless you bought one of those cheap hoses with crimped-on fittings from the hardware store) and reattach it. In other cases, you may just want to replace it since air hoses are cheap.


Next in line on your blaster is the water separator, which you need to drain on a regular basis. In dry climates, once or twice a day is sufficient, but in humid areas, you may need to empty it once every half hour. Any time air is compressed, it is squeezed under pressure, any moisture in the air is squeezed out, and it has to go somewhere. It is the job of the water separator to collect this moisture, hence the container at the bottom of the gadget.

The container only holds a certain amount of water, and when full, needs to be emptied. If you don’t drain the container, then you may as well not have paid for a water separator and resign yourself to the fact that you will have moisture clogs due to damp abrasive. When the separator’s container is full, the water has no other place to go but into the pressure pot. Damp abrasive will cause intermittent sputtering while blasting at best until the whole system shuts down with the caked-up abrasive clogging the hoses and blaster completely.

Only if you are a glutton for punishment will you let this happen more than once, because having to take a blaster apart in order to get all the damp abrasive out for drying is no picnic. Not only is it devoid of fun, but it will also cost you a lot of production time, so think about this one.


Next, check your pressure regulators and gauges to make sure they function properly. I am talking plural here since most of us use foot pedals, which have their own pressure regulator and gauge (unless you have one of those hopper attached blasters). I recommend covering the regulator and gauge with a clear cover (like a zip lock bag). In a dusty environment, it does not take much to prevent the regulator adjusting knob to quit turning because of abrasive that got into the threading. Also, the lens cover on the gauge gets almost opaque from all the scratches it sustains from being brushed/wiped “clean” to see the pressure setting. It is usually better to know which pressure you are blasting with than guessing and potentially ruining your project.

Make sure the seal to the pressure pot is tight and you don’t hear air hissing from it after pressurizing (this is much harder to do with a hopper mounted blaster); you may have to replace the seal. From the bottom of your blaster protrudes the valve body for the foot pedal (usually white). The abrasive passes through this valve into the sand hose, which goes into your cabinet. There is a valve with a handle (called mixing valve) attached to the outlet at the bottom of your blaster before the abrasive/air gets into the white foot pedal valve. This is the valve which regulates the abrasive flow, letting you adjust how much or how little abrasive you want in the airstream, which depends, of course, on the technique you are blasting with.

This is a ball valve and will eventually wear out from the abrasive eroding the closing ball on the inside and needs to be replaced sooner or later. If the valve is bad, you not only are unable to regulate the abrasive flow, but you also cannot shut it off to be using airflow only, which you get from the bypass hose on the blaster. The white valve for the foot pedal houses a rubber diaphragm on the inside which operates the on/off function of the air/abrasive flow. When the diaphragm develops a hole, you will notice that the foot pedal does not shut off the air/abrasive flow anymore. This is a common wear and tear part of your blaster and you should always have spare diaphragms in your shop. As soon as you notice that the air/abrasive flow does not shut completely off when you take your foot off the pedal, it is time to replace the diaphragm. Don’t wait until it’s convenient because in the meantime the white valve body will wear out and it costs way more to replace than a $2 rubber diaphragm!

The sand hose attached to the bottom of your pressure pot and going into the cabinet is a heavy duty reinforced hose. Yet, because it bends in a couple of places, you will eventually incur a hole somewhere close to the bend, since the abrasive going through the hose will erode the side walls of the hose. This situation will get your attention immediately, because it will cause abrasive to shoot out of the hole and fill the space around you and yourself with abrasive. You need to quickly shut off the air supply to your system with the main air valve. This does not happen very often with sand hoses, but with set ups, where the manufacturer chose to use an air hose from the bottom of the blaster to directly go into your cabinet, this is not an uncommon occurrence. Check your hoses on a regular schedule!


In the cabinet, we usually use an air hose for greater flexibility (hence the name flex hose) rather than the heavy duty sand hose. Here again, you will find the abrasive wearing through the hose where it bends. Knowing that this will happen, the flex hose is usually longer than necessary so that you can just cut off a piece and reattach it to the bulk head adapter on the inside of your cabinet.

The last two, but probably the most neglected items that will wear out for sure, are the nozzle cap on the end of the air hose inside the cabinet and the nozzle it holds. If you do not pay attention to the wear and enlarging of your nozzle, you will have to replace the nozzle cap more often than necessary because the nozzle will wear through, and the abrasive then attacks the nozzle cap with vigor.

When the nozzle enlarges past a useful size, you will hear your compressor kick in frequently. Eventually, it will run all the time to try to keep up with the air requirement of the enlarged nozzle. How quickly this happens depends on the size of your compressor; smaller compressors will not be able to power an oversized nozzle very long. If you do this on a regular basis, you will cause your compressor to need maintenance and repair much sooner than necessary. Not only will this cost money, it will also cause down time since you can’t blast without the compressor. Using your nozzle past a useful size will affect your blasting as well, since it is difficult to control shaping small areas of carving if you are using the equivalent of a fire hose to blast with.

Well, I think this gives you quite a check list to deal with for the time being. Next time, we will take a closer look at dust collectors, cyclone separators and cabinets to complete our maintenance survey. Make it a New Year’s resolution to maintain your equipment so that you can work more efficiently and also save money. If you have any questions or comments, you can always reach me at

© Ruth L Dobbins 2009