Booth #4 – Moisture

booth_4In 1997 Micky and I made our first attempt at fulfilling our dream of living in the Pacific North West. Without much of a plan, we rolled into town with our 3-year-old and all our stuff, moved into an apartment and started job-hunting. Looking back on it now, it seems like a crazy and impulsive move, but such was our passion about the beauty up north. Within a couple weeks I was fortunate enough to end up with a job at Chuck Franklin Glass Studio. Although they already had a sandblast booth, no one in the studio was specifically specializing in sandblasting at that time. Even though it wasn’t one that I built, booth #4 is worth mentioning in this series because I learned from it something I may never have otherwise learned.

If this is an issue specific to regions with cold wet climates I can’t say for certain – the problem though was that the sandblast booth had been built into the back corner utilizing the existing block and concrete exterior walls of the building as two of it’s four walls – as opposed to building it away from those walls. The result seems to have been persistently wet sand. The lower portions of these walls were below ground level, so perhaps it was caused by actual tiny leaks, or could it have been condensation? Whatever the case, I know I’ll always build away from exterior walls, and not take that risk.

It’s funny though, I do remember that when I originally started talking about moving up here that other glass artists had said that it is too wet for sandblasting – that I would have too many problems with moisture in the lines. I must say that now that I’ve been up here sandblasting now for quite a few years, that I actually have LESS trouble than I did in Phoenix. It leads me to conclude that you can have moisture issues anywhere, that it probably has less to do with the environment and is much more about maintaining, and having enough in line moisture traps. In phoenix I usually had only one, whereas right now, I think I have a couple on any given line. They aren’t horribly expensive, so why not? If this holds true everywhere, I’m not sure. I have never sandblasted for example in places like Florida or Houston.

My memories of working at Chuck’s that year are among my fondest. The greenery, clouds, misty air and a great bunch of co-workers were hard to leave, but circumstance pulled us back to Phoenix. Suddenly I found myself back working in booth #3 again as if indeed somehow it really had been only a dream.

During the decade it took for us to get back up here I had another opportunity at booth-building. With the help of the new boss, booth #5 turned out to be a significant leap forward in function.

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Booth #3 – Better but still wrong

TD3It was approximately 1995 – The new building was of block construction, was a rental, and although situated in an industrial area, had neighboring businesses to consider. These are common hurtles that often have to be overcome when building a sandblast booth in a commercial setting. There were also genuine construction issues to solve… what we came up with was not ideal – but it DID work … well sorta.

It was a fun one to build – the boss was willing to put some money into it and we had given it’s design a great deal of thought. We agreed that air needed to be pulled FROM it, but how could we do this without cutting a hole through the block exterior?The solution was that we built it in front of the backdoor, and used the door as the place for the exhaust. The first consideration was maintaining the functionality of the door for security and other obvious practical reasons. The complicating factor though was that we didn’t really want to lose valuable working space inside by building the exhaust device into the interior of the booth.

What I ended up making looked sort of like a wheel barrel in the shape of a refrigerator. The top half of the beast was a large swamp cooler (squirrel cage fan) and the bottom half was a filtered dust collection chamber. I attached a couple of ergonomically placed fold-down handles recessed into its front that I could pull up to use to roll it into place into the door opening. It was of course NOT light-weight and was more than a bit awkward – but it really only took 2-5 seconds to get it into place, and I was operational for the day.

I have no photos of the contraption, but I remember it very well. In taking this trip down memory lane I was surprised when I mentally reviewed the way it was designed and how it had performed. It’s embarrassing really – I had gotten so far as to realize that air should be sucked from the booth, then turned right around and decided to BLOW it into a filtered box! I’m sorry but this was again wrong. I cant remember this specifically, but I’ll bet those filters puffed out far enough that escape holes opened up. Either that or they just blew right off and maybe we forgot to ever put them back on. Again, not knowing any better at the time, we thought it worked great.

My favorite thing about booth#3 was the load-in door. The structure being situated as it was, next to where we parked the company truck, there would have been a conflict in creating any kind of swinging door, so the boss located some heavy-duty track hardware and I made one big huge hanging/rolling door. It was extremely cool.

When pulling air through a sandblast booth, one thing that is very important is an appropriate configuration of intake openings – where they are, and what size they are can affect how the air moves and how well the fan or fans perform. If the door slams shut when you turn the fan on, it’s probably a good indication that your intakes are too small. Its perfect when there is just enough negative air pressure that the door gently closes. The slower the door closes, the slower the air is moving through the booth. The slower the air moves, the more direct rout it takes to the filter. Intense negative air pressure can also put a strain on the fan motor (or so I’ve been told).

The intake openings in booth #3 were in the ceiling. You can see them in the third picture (click on the illustration). The reason they have filters has nothing to do with dust collecting, it was actually to help keep sand from accidentally flying out – I guess during those times when I would be shooting straight up right? Hey – It could happen!

Everything so far told in the sandblast booth saga took place in and around Phoenix Az. where I had lived my entire life up to that point. The next element of the story however takes us to a far away land called Portland Oregon where I learned new things about moisture in booth #4.

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In the Beginning

ChandlerShedActually, in the beginning there was no booth. At the studio where I had first been employed as a glass artist, I had worked outdoors in a vacant lot. They had been doing it there for I don’t know how many years, and so it was like standing amongst blinding white dunes of silica. Thinking back on it has that same surreal quality as remembering that there was a time when people smoked aboard commercial airline flights or while shopping for groceries – just doesn’t seem real but it was, you know?

The other place where I was blasting back then was under a roof attached to an old shed, but still basically without walls. I came across this photo from 1987 that shows me working at night out behind a place I was renting in Chandler Arizona. I was also using the inside of the shed for building stained glass windows. As enjoyable as it can be to work outside, there are many disadvantages to deal with, such as the little gifts that cats leave for you in your sand.

The next time I was setting up, I decided it was time to make some changes. I thought I should get out of the weather, get less noisy, and although silica sand was dirt cheap, I still wanted to contain and recycle it. By the way, for those of you that may be wanting to become sandblasters, do NOT use silica sand. Even though you really shouldn’t breathe large amounts of any abrasive, some are worse than others. It’s probably not a good idea to use one that has its own disease named for it (silicosis). After a few years I switched to aluminum oxide and still take many precautions to avoid breathing it.

Anyway, I needed to build something, but remember, this was the olden days, before “google”and I had no one to consult with, no example to work from. I doubt I had even ever heard of the term sandblast booth. It seemed simple enough though; it was to be a structure big enough to lean a piece of glass in, and to be able to sit or stand comfortably in front of it. Air needed to move through it. Large particles needed to stay, small needed to leave and be collected elsewhere. There needed to be lots of light. Not much more to it right?

We had an over-sized two car garage that had an area which seemed ideal. There was a swamp cooler mounted outside one of the exterior walls at just above eye level which was just blowing air straight in through a hole in the wall. I built the booth right in front of the hole and brought the air through to the front of the booth via a metal box.

The metal box had a sliding panel that could drop however much air I wanted into the booth, or could be slid shut so that the maximum amount of air could be cooling the garage. Those of you that know anything about this stuff will see I was already going in the wrong direction.

There are two ways to move air through a sandblast booth; pushing and pulling. Only one of those ways is the right way. I think when people go about taking on the task without any prior experience or don’t have the benefit of any guidance, they will most often choose the wrong way, without even thinking twice about it. It seems the natural choice because when we use a fan to move air in our everyday lives, we don’t really ever point them AWAY from us in order to cool off.

The only way blowing air into the booth works out well at all is if the air is then allowed to exit an unrestricted hole, in other words – no filters … but who would do that in this day an age? The moment any kind of filter enters the picture the problems begin. The air inside the booth becomes pressurized. The pressurized air of course goes wherever it is easiest to go. Question: which is the path of least resistance, a filter … or the crack under the door? That’s right! EVERYTHING has to be sealed completely!

Even if you do actually manage to absolutely seal it up, the problems don’t end there. Air that is being pushed into the space at a considerable velocity is then expected to exit through a filter that cannot help but to slow it down. The incoming air isn’t going to stroll up and wait in line at the filter, it’s going to find something else to do until it loses enough speed to take its turn. It races around for a while and so what you end up with is a continuously stirred fog that gets worse and worse as the filter becomes more and more restrictive with every passing moment. The more restrictive it becomes, the farther the dust shoots out the little holes that you have failed to seal up, effectively dusting your entire workplace so badly you begin to wonder why you even built a booth at all.

For as much that is wrong about pushing air in, there is all the more that is right about pulling it out. Air is now trying to get in everywhere it can, so technically you don’t really have to worry so much about sealing it up. Before I get into that, I should mention the second sandblast booth I worked in, which fell into a third category. Air was neither pushed in OR pulled out, instead it hung in a stagnant cloud around a non-functional bag style collector that had been plopped right inside the booth. Think about that. INSIDE the booth. Believe me, it was better to not even turn the thing on. I didn’t have anything to do with the design or construction of that booth, but for simplicity’s sake I’m going to call it booth#2. Luckily I only had to work in it briefly – the company was about to re-locate, and I had been hired on just in time to build booth#3 – which will be the next subject in this multi-post series.

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NewBooth5Often the search queries that bring people to the websites of sandblasters look something like this: “How to build a sandblast booth” Here is a sample from this week alone:

– “build a sand blast booth”
– “large sand blast booth”
– “pictures of sandblasting booths”
– “sandblast booth”
– “sandblasting booth for glass”
– “walk in sandblast booth”
– “walk in sandblasting booths”

If this is the type of question that has brought you here and even if this means that you are “the competition” – I am more than happy to share what I know so far. I think the first one I did was in 1988 or 89. Since then I’ve built five others, improving as I went along. I’ll start back at the beginning and recount the whole learning process, which is on-going I can assure you. There is always more to learn, so if anyone reading this has any tips or suggestions I would certainly appreciate them. I’m going to have to break this epic tale into multiple posts, I had know idea it was going to be so long.

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