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Posted on December 29, 2015 Many of us have a blasting booth, it is a foundation tool for making a world class restoration happen. What follows are some preliminary notes on what I have found as simple but effective tricks and traps in working a booth. I will add to this over time, so check back ofter. Ask any questions you might have right in this thread and I will answer them. If you enjoyed or found this useful, say something. The folks that work to make this all happen enjoy knowing that the legions that read it actually find it useful. After all, we are busy too.
1. Health: No, booth work is not healthy work unless you take every precaution to make it so. No matter what anybody tells you, its all about set-up and process that makes a booth a place that one can spend hours and not be compromised over the long term. Bead blasting requires a thoughtful, serious review of equipment, process and clean-up. Sadly, there are many cases of people radically effecting their health using a booth. So, with that sober introduction, lets go…
Lungs…
– We never shoot sand in a closed booth, ever. Sand can ruin your lungs in short order. If you are shooting sand, stop. If you have never shot sand, don’t. There are some that shoot sand in the outside environment or in a special room with special positive pressure head gear….and there are those that shoot it with bad equipment….they get Silicosis. Tens of thousands did in WWI and WWII working in the shipyards, even those that worked on poor clean ups after the blasting had been done. The science is settled on this one….Do Not Shoot Sand. We will get back to this latter.
– Venting your booth outside is always better than venting your booth inside. Not only will the environment you work in stay much cleaner, but the low pressure nature of an external venting system will lower vacuum back pressure and save your motor. Keep all your tubing runs short as possible. Use straight walled pipe if you can. I exit post vacuum by sending a hose through a typical automotive exhaust port on my garage door. The dump from motor exit to outside is less than six feet.
– Venting inside requires a superb quality final filter bad assembly after the vacuum motor exit. You will need to empty it and keep it clean. They dry slowly, so get two bags if you are constantly banging on the blaster.
– 90 degree fittings are the largest contributor (besides a dirty final filter) to restriction in air flow, get them out of the pathway. Some of the largest and best manufacturers terminate their runs post the vacuum with a 90 degree down bend to the final filter bag. Remove it, use a straight pipe or a 45 degree bend. You will immediately hear the motor relax and see the draw out increase. The final filter bag doesn’t care what angle it is at…AND….if you use a straight pipe out of the vacuum and the final filter bag has material in it it will inflate straight out…but will droop down, letting you know its time to clean it out.
– Tape every fitting with quality tape. I use electrical tape. Pass a candle flame around every joint and fitting, if the flame dances….fix it until it is stone flat. The biggest leak will be right a the post vacuum final run. I used silicone sealant until things went flat. No more dust, folks. On a standing black gloss painted vacuum, one can work it for hours and never see dust on top when you swipe your finger, Clean is clean. If there is dust, find it, fix it.
– We mask up (and use eye protect) whenever we work with media, no exceptions. From carry to dump…..mask.
– When emptying media out of a booth from a bottom trap, use gloves, mask and eye protection. I use a Home Depot orange bucket with their superb sealable screw on top (not the cheap pop on top.) If you haven’t seen one of these tops (2 piece…rim and screw top) ask for it as they are excellent for storage. Back to the trap, clean the trap as best as you can. The trap can be a source of leaking, especially when you back-pressure the gun to clear it out in use. When you are done emptying media, take a cheap plastic shopping bag and some painters tape and place the bad over the trap and tape it up to the main funnel body. Much, much cleaner this way. You will be surprised when you take the bag off next time.Vacuum up the floor with a floor vacuum that can handle plaster dust, in other words a vacuum with a good filter.
– Best way to fill you booth is to place the sealed media bag into the booth, lay a razor knife in the booth. Close and lock the door, don the gloves and cut the bag open IN THE BOOTH. I always run a booth with a secondary pressure air line, so after a refill I blow the grates, doors, walls clean. In fact I never open the door without blowing the booth clean.
– If you can afford it and use expensive media (I’ll cover the media types at some point) buy the post trap kit that many offer. It will sort out good (heavier) media as it exits the booth so it can be collected and returned to the booth BEFORE it goes to the vacuum canister.
– Always allow your booth to “filter out” after you use it and BEFORE you open the door. 3-5 minutes is all it takes. If you open the door right after you are done the air will kick right out the intake filter. Let the booth clear. Most companies offer an intake filter, get it.
Eyes…
– I use a full face mask right over my face mask. This unit comfortable and I never have to worry about my whole face. These are great units.
– Did you know that the next generation of booth will have a mandatory pressure kill switch whenever you open the door? Why? Folks blasting their faces when they go in.
Door open? Mask and eye protection….might as well protect your whole face.
– Lights: Good lighting is important. Use as bright a light as you need, but do not end up staring at a bright bulb a foot away! Tip your lights so the brightness does not “star you in the face.”
Ears….
– Compressors all operate over 100 dB, most vacuum operate over 110 dB. Spend hours with them in close proximity and you will loose your hearing. Think you won’t? You are already deaf. People that know me well know that I spent years working on sound suppression. I know this subject better than most, trust me on this…plug up or use a head phone set..or if your rig screams…BOTH. I run the quietest compressor that uses a piston and it is 40 feet away. My vacuum is sound insulated. I still plug up every time. If you are lucky enough to run your compressor in the next room…well you win! If you stop running your booth and your hearing is muffled or your ears are ringing….well….that would be your first sign, folks.
Hands…
– Putting your hands in huge rubber gloves leads to sweat build up…and that leads to bacteria and mold growth over time. Simple fix…when you are done simple pull the gloves back through the holes so that you walk away with them inside out. They will be bone dry when you come back if your area is in a normal humidity place.
– Always clean your hands if the are a mess BEFORE you glove up. I use typical auto supply waterless cleaner (GoJo.) Clean Hands = Clean Gloves.
– Did you know that a sign that your booth has an intake restriction is that your gloves super inflate when the vacuum is on? Gloves should be somewhat limp. If you have a restriction in your intake the vacuum will literally suck air at the seams on the gloves. What causes a restriction? Being too close to the wall. Having placed a rag on top of the booth and it got sucked into the intake maze.
Feet and back…
– Stand on a soft foot mat. If you use a pressure peddle, kick off BOTH shoes and relax your spine.
– Posture! My booth needed to go up 6″ before I could work with my back straight and my arms relaxed. What a difference! I used some left over 4x4s and 2x4s and supported the whole stand run.
2. Process. The what may work best in the booth.
Before we begin, the check lists:
Before you start blasting:
1. Check that your exit air flow is ready to work.
2. Check that your line pressures are between 80-85 psi
3. Check that your water separator is empty
4. Check that your vacuum has been “tapped” (lift and gently tap on the floor with two pieces of cardboard under the vacuum) to clean the air filter.
5. Check that your air inlet is open
6. Close your post blast media recovery valve (if present) is closed.
7. Mask on
8. Eye protection on
9. Ear protection on
10. Lights working
11. Visibility good.
After you blast:
1. Blow out the booth with air, back blow media pull-up hose.
2. Lay gun facing away from door
3. Let the booth exhaust run for an additional 4-5 minutes
4. Empty parts
5. Turn off lights
6. Pull gloves out (turn inside out to dry).
7. Tap the vacuum on the floor to clean filter
8. Check exit line
9. Empty water out of separator
10 Empty captured post trap media from the filter (if present.)
11. Turn off compressor
Air Pressure:
– 80 to 85 psi is the working pressure for most quality media materials. Less pressure are your work will take longer (your material will last much longer). More pressure and your work may take shorter time (and your media will vaporize, literally destroying itself super fast.)
– How long will media last? Most folks would like to know, so here it is. Media will last 4 – 6 months at a use rate of 5 hours a week when shot at the proper air pressure. This also depends on proper distance from gun blast tip to target, 4″ – 6″ inches.) Know that many folks literally suck their media out of their booths because of restricted air intakes. The vacuum WILL pull media right out of a booth if it has a restriction.
– How do I know m media is finished? Number one is an obvious amount of media clouding in the booth. Number two is a lack of overall removal capability. Number 3 is that media is actually diminished in volume in the holding bin.
– Can I just add more media to old media. Yes you can…No you shouldn’t. Old, spent media is a waste of time, get it out and start with fresh media rather than “diluting” the media mix.
– How long will my replaceable protective film on the inside glass last? First, blast pressure plays a role here, keep it at 80-85 psi. Second, shooting distance away from the film plays a big role here, shoot as far back in your booth as you can. Thirdly, shooting angle plays a roll here. Straight bounce back, coming right back at the film reduces life. Shoot at an angle with the gun facing the rear corner near the vacuum exit port for longest bounce back life. I get about 8-12 hours of life from a disposable shield
– Can I clean the replaceable inside film? Absolutely and you should. I do it after every carriage is done. And, this is how I do it. First let the booth vacuum run 3-4 minutes before opening the door after the final work is done. Open the door and empty all the parts. I have magnetic hooks hanging from the top of my booth so I hang my guns up.
http://www.homedepot.com/p/MASTER-MAGNETICS-65-lb-Magnetic-Pull-Hook-07580HD/202639939
Then I place a bottle of window cleaner and two paper towels into the booth. Close the door, don the gloves, turn on the light (without the vacuum on) and clean the glass from the outside.
– How to replace disposable shields? My unit is a TP Tools unit (more on this later) so I DO NOT do this by putting the sheet on from the inside. I simply remove the whole front glass. Strip off the old one, clean both side of the window well and replace with a new sheet. Check your gasket. Do not over tighten the screws. What a difference!
– How important is water removal from your pressure lines? Very. The gun will actually pulse and stop performing when the humidity goes up. Run a water removal canister and check it every day you use the system. Same for your compressor tank. Great time to check your line pressure gauge as well. Don’t run a pressure gauge or a water separator? Rust and destroyed media.
– How often do I change my blast gun tip and air venturi? Depends on your media, but you will see pulsing as you spray and worsening patterning of lift. I spent the money on a carbide tip and I have yet to see wear, repeat, no tip changes.
– Should I rotate my tips and when? Yes, 1/4 turn every three hours of blast time for BOTH the tip and air venturi. Mark it with a black pen, loosen, rotate, tighten.
– How should one “blow out” a booth after work? First, back blow the pick up tube. Then, start at the wall and floor grate near the air exit wall, clean everything back to the door. I run overlap shields on the door seals so I can blow right at the door. Avoid shooting pressurized directly at the air entry vent. When you reach the door, quickly blow back to the exit wall. Blow off your lights too. Let the vacuum run 3-4 minutes before opening the door.
– How long should a single blasting session last? ONE HOUR and then we stop and put our hand on the VACUUM as that is the limiter to longer work sessions. If it is warm to hot, you are done until it cools down.
MEDIA TYPES and RESULTS
I will post some photos when I can of examples of all the media results. I use TP Tools media so that is the point of reference for me.
Smaller the number the courser the media in most instances.
– GLASS BEAD 60-80 – This is a round bead product, This is the the finest surface possible. It is also the slowest, most time consuming media to shoot. The result is a very fine, almost polished presentation with absolutely minimal surface distortion and disturbance. If you are shooting a rare trolley that has a great surface or a good surface and are willing to give the blasting twice as long, well this is your product. As close to the original pour surface as can be found. Silver in color smooth as can be. One can shoot brass badges safely, tin badges safely, most aluminum parts (hold the gun back on anything soft and work it first at a distance.) If I am concerned about making a particular trolley a real presentation piece, I have two choices and this is one of them. Lasts about 4 months at 80-85 psi. Go to 90 psi and it will last less than a month, Minimal tip wear for less expensive tips. With a carbide tip, the tip will last a long, long, long time. Minimal clouding and dust. Clean white coloration, satin smooth.
How long to shoot a chassis? A full sized chassis with two hay sling pulleys will require 1 and 1/2 hours of careful work as a minimum. Cross Drafts with their drops will require more like two.
– SPEED BEAD 50-80 – A mix of glass bead and aluminum oxide. Another product that leaves a better than medium finish. Not as fine as GLASS BEAD, but very close. Better for hardened paints, better for light grease, better for more pitted surfaces than glass bead. Approximately 1/3 faster than glass bead. This is a fine-fine medium product. Better for more pitted and rusted trolleys. One coat of primer and one top coat and its a fine surface. This is a very good surface finish that does not require the time of round glass bead. Excellent dust levels as well. Satin a satin/silver finish, still long lasting. Because of the use of aluminum oxide in the mix along with glass bead it cuts more and you will see more tip wear with normal tips. Do not use for internal engine parts. Lasts approximately 4 months at 5 hours a week at correct pressures.
How long to shoot a chassis? A full sized chassis with two hay sling pulleys will require 1 hour of careful work maximum. Cross Drafts with their drops will require more like one and 1/2 hours.
– SKAT MAGIC 40-80 – Folks, this is a fast media to blast with. This is old windshield glass roller crushed down to a fine, consistent sharp edged mix. Fast cleaning, almost half the time of glass bead and Speed bead, did I say this stuff is fast? Surface has a medium finish that is not polished, is not satin, is not white….it is slightly sparkling as this media mico cuts. One coat of primer and one coat of top paint and…its gone. Low dust, will burn through your normal tips faster than glass bead and speed bead. Paint is removed without question as is most hard grease. Removes scale and heavier rust but will not smooth out a surface….it is finer than that. Lasts approximately 4 months at 5 hours a week at correct pressures
How long to shoot a chassis? A full sized chassis with two hay sling pulleys will require 45 minutes of careful work maximum. Cross Drafts with their drops will require more like one hour.
– FIRST CHOICE 60-90 – Man-made concoction. Aside from glass bead, this is my second favorite media. Leave a smooth satin/white finish. Slightly, and I mean slightly lighter finish than glass bead. Removes paint and hard grease slowly, but faster than glass bead. Low dust and long lasting. Fairly easy on the normal tip too. Fast than bead by 1/4. This is what I use except for say a cut-out Jordan with an already lovely surface. Did you like my “Wortman & Ward Double 8?” Well, this is what I basted it with. Lasts approximately 4 months at 5 hours a week at correct pressures
How long to shoot a chassis? A full sized chassis with two hay sling pulleys will require 1 hour and 1/4 of careful work maximum. Cross Drafts with their drops will require more like one and 45 minutes hours.
Dan[/vc_column_text][vc_column_text]