Sandblasting  for the Studio Artist

February 01, 2018 2 Comments

When I first heard the word sandblasting I conjured up images of men in full bodysuits cleaning rusted chemical vessels and cleaning old paint off of cars.  A far cry from how we use sandblasting as a studio artist.  I am sure there are some artists who do this type of work but that is beyond the scope of this blog.  The sandblasting I am referring to is what I needed to do as a glass artist or enamel artist. In this blog I will primarily cover the equipment.  In future blogs we will show more  applications of sandblasting in how I use it in developing my art. 

The sandblaster that I will discuss is  a gravity fed Cabinet unit that sits in the corner of many studios.  The cabinet  can come in a small tabletop versions or larger cabinets. There are many different brands but more about that later. The large cabinet below is the unit I own which I bought from Northern Tool supply on sale. Initially I tried to use a hepa shop vacuum for dust collection, but I later bought a Econoline 100 cfm commercial dust collection system as I was tired of the dust. I added 2 sets of lights as you can never have enough light in the dusty environment.  Next I wired the lights and the vacuum together on one switch on the outside of the cabinet so when they are turned on, they both start.

It's great if you keep an extra viewing cover for the  working window as it will scratch and make it difficult to see thru.  In my unit I can change out disposable plastic covers.  Check your seals on all the doors to make sure the gaskets are fresh and seal well.

Replace the blasting gloves when they dry out, especially if you blast toward your glove hand. If your gloves get wet it is hard to get your hands into them. So if you dry your hands well before putting on the gloves this is not an issue.

I protect the glass I work on from the metal grates  in my sandblaster with some old rubber mats that I have cut into a couple of strips. 

​I keep an extra set of gloves on hand so when I have a project deadline so I can finish it without an emergency  trip to the Houston, or Amazon.
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If you buy a tabletop unit be sure it has a vacuum and it is connected to it or it will be a dangerous dust machine. 

These are  the units that I would recommend. There are several other options available from Cyclone another great company.  I do not have a local supplier of Cyclone  so I stayed with Econoline. Use a company you trust and that can sell you replacement parts, but more importantly can help you troubleshoot.  An invaluable resource. My local sandblasting supplier is Clemtex and they are great but only in Texas. 

  

I would also recommend  HIS Glassworks as an excellent resource and supplier. 

 
Econoline is a great manufacturer, and makes all the parts I have had to put in my unit to make it work without hassle. I highly recommend them

But the most important thing to understand about sandblasting is that it is all about the volume of air you run thru your gun. 

So I am going to diverge now to some simple concepts that make this work or fail.  Your compressor is one of the most important purchases you make in your studio.  The typical compressor that runs a nail gun will not come close to making a large cabinet sandblaster work.  It may work for a bench top unit at very low pressures,  but it does not have the volume of air needed to run a sandblasting gun at working pressures.

So we need a serious compressor, because that's what propels air which carries the media from your gun to your work and your art.   No air and you are struggling.  The whole system needs to work together.
 
So when I went compressor shopping this was what was  I had to figure out before I could formulate a my shopping list:

First: I had to determine what it is that I would  be sandblasting so that I  could match the air needs of a compressor ,with the size of my sandblasting gun and more importantly the sizeof the  tips in the sandblasting  gun.  Also to determine the size of the cabinet.
Second:  What was I going to do to protect my lungs from the dust a sandblaster generates.  Same protection concerns with the noise of a compressor.
Third:  What medium was I going to use on my art...shells, garnet, aluminum oxide, or silicon carbide?  Never sand!!!! as it may cause silicosis a deadly lung disease.
Forth: How much did I think I would use this device (you will find you can't go many days without using it) and what type of compressor did I need.
Fifth: Cost  

So to answer question one: I knew I would be working with Steel, aluminum, wood, stainless steel and glass and enamels.  This posed some planning issues.  I had to keep the media separate that I was using on steel and other metals as I did not want to contaminate my enamel work or my glasswork.  A simple switching of materials and careful labeling was the solution for me.  If I was in a critical production area I would need a separate cabinet for steel and stainless steel.  But not an issue for my art.

Next question was on protecting my eyes, ears and lungs.  Wearing hearing protection, a dust filter mask with a p100 cartridge and a face shield covered these bases. Here are the ones I use. The face mask is great because it protects your entire face and changing the  polycarbonate shield is easy when they get to scratched and dirty.  
Uvex Bionic Face Shield with Clear Polycarbonate Visor (S8500)


3M 6391 P100 Reusable Respirator Gas Mask - Large

Professional Safety Ear Muffs by Decibel Defense - 37dB NRR - The HIGHEST Rated & MOST COMFORTABLE Ear Protection - Firearm & Industrial Use - THE BEST HEARING PROTECTION...GUARANTEED (PINK)

 So after calling my fellow artists and doing some online research I decided I would primarily use aluminum oxide medium.  Especially after talking to Michael Glancy who teaches at the Rhode Island School for Design and does amazing glass and electroforming work.  I decided on using 180 mesh aluminum oxide.  As I have developed in my glass work I noticed other glass artists use up to 220 grit.  Only put 3 to 4 inches of grit in your unit.  This makes it easier to change and keep fresh.  The more you use the grit, the finer it gets and the results change.  Something to keep in mind.
The coarser the grit (smaller the numbers) 60, 80 , 100, 120  it will cut faster but will it leave a much rougher surface on your work.

I use 180 grit and then either  fire polish in my kiln or coat the surface with Watco natural Danish finish.    
​Be sure your unit is grounded as aluminum oxide can generate static electricity.  A non issue if the unit is well grounded.
Brown Aluminum Oxide Blast Abrasive Media, 180 Mesh Size, Very Fine Grit (25 LBS)

My next question was: How much would I use this tool?
I underestimated how valuable a tool this would be.   I use it several days of the week. 
So buying a good compressor was in hindsight a great purchase that made this system work.

Next was the issue of cost.  I have learned through this process that you will save money and time if you buy a quality unit from a professional sandblasting source close to you where you live. Buy it as a set.  This way  you can get parts, supplies and most importantly advice on how the unit works and what to do if it stops working.  For me Clemtex is my local supplier.  They are amazing advice resource and I would highly recommend them. 

My sandblasting cabinet suggested  that you need  a  Minimum air volume of 15 CFM @ 80 psi with the factory supplied gun that broke every couple of weeks.  The more important issue is the type of gun I am now using and it openings.  CFM is cubic feet per minute and is an important number to look at when buying a compressor.  My sandblasting gun runs at 12 cfm with the nozzles I have in it.    
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So when learning about compressors here was what I needed:
1.  A large 60 to 80 gallon tank to hold a good volume of air so the motor is not constantly running.
​2. I preferred a  2 stage compressor. The main difference between single and two stage compressors is the number of times that air gets compressed between the inlet valve and the tool nozzle. In a single stage compressor, the air is compressed one time; in a two stage compressor, the air is compressed twice for double the pressure and a more efficient way to make compressed air.
3.    A 220v circuit a dedicated  40 to 50 amp power supply.  Please have an electrician wire this for you.
So after doing my homework this is what I bought and it is a workhorse.
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below are the links to buy this compressor
- Quincy QT-54 Splash Lubricated Reciprocating Air Compressor - 5 HP, 230 Volt, 1 Phase, 60-Gallon Vertical, Model 2V41C60VC

Next to learn was an education about compressed air. 

When air becomes compressed it becomes hot. ( think of the components of air...Nitrogen ,oxygen, co2 and water ie humidity)  So the  water vapor either needs to be removed with and evaporator or it collects in your lines.  It will collect at the bottom of the compressor tank as this is before any evaporator you have after the compressor. 

So it is imperative to have as short of distance in  your air lines between your sandblaster and the compressor as possible.  Otherwise water vapor will collect in the lines and clump your blasting media.

It is also important to drain the bottom of your compressor after using it  to remove the water and keep the bottom from rusting.  I installed a small pvc line from the valve at the base of my compressor thru the wall to the outside to vent the water.  When I open the  valve on the bottom of the compressor, the water that spits out causes a nasty mess on the floor of your studio, but with the line  outside problem solved.

I also added an Air Line Filter to help remove water from the compressed air just before the compressed air goes into the cabinet.  You may need a plumber to install you air lines.  This is not hard if you are a bit handy. I used flexible lines that are easy to replace and move around.  I used rigid galvanized pipe from the compressor to my other filters and connections. Remember compressed air is wet and hot.

The original controls that ran the syphon and air from northern  tool were a constant pain to keep working. So when I upgraded to a professional sandblasting gun I redid the controls and after 18 months of steady use  I have never have had an issue.   My point is that  of buying from a sandblasting professional originally, would have solved a great deal of struggle and I think may have been cheaper.

Next is the Blasting Gun.  Cheap guns mean lots of repairs and down time. A good quality gun that you take care and rotate the nozzles will last a lifetime.  You may after a great deal of use have to replace a nozzle. Be sure and rotate them to prevent lopsided wear. Again match the gun to your air supply or it will not work!

This is what I use.

This is how a sandblasting gun works with a siphon system such as a gravity fed blasting cabinet.

 The blasting medium  sits in the bottom of your cabinet and is sucked into your gun via a siphon tube.
The media has a life of 10 to 15 cycles and I put just enough media in the cabinet to cover the siphon tube by 3 or 4 inches.  That way it is easier to switch media when it is worn out.  As you can see in the drawing there are 2 different nozzles in this gun labeled B and D.  They need to be rotated every month so they wear evenly.  It is a simple task of loosening a set screw and rotating the compressed air nozzle and the sandblasting exit carbide nozzle.  If you have a different type of gun ask your supplier about gun maintenance. A good gun will last years if taken care of.

​If nothing is coming out of your gun you either have a clogged suction line, no air pressure to your gun, or you  ran out of blasting medium.

On the compressor there are 2 gauges that you will need to know about. 1 is the pressure gauge on your tank that tells you how much pressure is in the tank.  The second is regulator/ water trap  that  is  adjustable and controls the  pressure and  air being released to your sandblaster. You will see this in the video. When you buy one make sure you know the size of pipe you will be using for your compressor and buy the one designed for that pipe size.  Some compressor come with one or 2 gauges. 

The water trap is essential for removing water and you need to drain it when you see water in the bowl.  Turn the air compressor off and let all air out of the lines then follow the instructions to drain the water out of the bowl and then your ready to go again. I use a second air filter just prior to my sandblasting unit to make sure no water has settled in line from compressor to sandblaster. A good regulator and filter will last many years. 

This is regulator and filter I use for 3/8  pipe
PneumaticPlus SAW3000M-N03BG Air Filter Regulator Combo Piggyback, 3/8" Pipe Size, NPT-Manual Drain, Poly Bowl with Gauge

This is the filter I have just before air enters my sandblasting cabinet. It is for 3/8 inch pipe.
PneumaticPlus SAF3000M-N03B Compressed Air Particulate Filter, 3/8" Pipe Size, NPT-Manual Drain, Poly Bowl, 10 μm

Here are some useful settings  for me

12 to 20 psi for light blasting and removing fiber paper residual..
30 to 40 psi for surface blasting and deeper issues.

I used around 75 psi for finishing glass with a powdery finish that I finish coat with Watco Natural danish oil. 

For enamel removal I use 85 to 90 psi.
You need to keep the gun moving across the work.  Holding it in 1 spot will create a hole thru the enamel, or pit the glass  which may be what you want as an artistic feature, but in general, it is not pretty.  So, my motto is "go slow and inspect often".  I let the vacuum run for 20 seconds after shutting off the compressed air from the foot pedal to clear the cabinet of dust.  My vacuum sucks at 100 cfm.  Most shop vacs are less efficient.  You do not want to breath the media.

You will need to wash off the remaining residual blasting grit  in water before re-firing your work

You need to see what works for you..It a learning process.

I use my sandblaster for so many things:
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1.  For removing devitrification, or shelf separator that stuck during firing.
2.  Adding textures and some carving using a green rubber resist called buttercut. It is from 3m. It works great to protect areas from sandblasting.  It  can be  cut with a craft knife or digital cutting printer like a silhouette. see below.  Keep it sealed as it dries out.
If you look at my blog on making and eutectic fired enamel bowl you can see how this green buttercut resist  is used,  I love it.

My daughter cuts this on her  silhouette printer and makes etched appearing designs on glass. ​

Buttercut stencil below
3M Sandblast Stencil - Hand-Cut Splice Free 510 Green, 12-3/4 in x 10 yd, 1 per case

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Silhouette Cameo Digital Craft Cutter Machine Printer for PC or MAC - Includes 51 exclusive cuttable designs and a $10 gift card to Silhouette Online Store - With a BONUS Replacement Blade
  3.  To create a tooth in metals that I enamel like steel or stainless steel.
4.  To erase enamel bubbles or mistakes.
5.  To clean metals before I apply a patina.  
6.  To add a texture by sculpting deeper in the surface of glass or enamel.
7.  To add a fabulous texture to wood.
8.  To remove Iridized coatings on glass.
9. To remove the mysterious spots that appear on glass and enamels from something falling off the sides of the kiln, or other contaminants.  For glass re-firing to  a fire polish  at 1340 to 1390 with appropriate annealing after sandblasting often works, as does a diamond bit in a foredoom tool.
10.  To get a matt surface I lightly sandblast and re-fire  around 1100 to 1175 with appropriate annealing.
​11.  and so much more......

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So what are the problems with Sandblasting Glass
1.  Glass has small bubbles and you may open them up when you sandblast.  You can re-fire the work or fill with glass power in the holes, or fill the holes up with a clear epoxy such as HXTAL NYL-1 (sold by HIS Glass) 
2.  You may need another product such a Watco, Armour Etch Cream 
all or Liquid Luster to get your final desired finish. Use appropriate ventilation and skin and eye protection.

3. Be sure to wash your glass thoroughly before re-fireing in your kiln. If not you will fuse the residual into your glass and make a mess.

4.  You need to protect your glass from the metal shelf of the sandblaster.  I use wood supports or cut up old car mats that I cut in 2 inch strips laid on the floor of the sandblaster to protect my work.
5.  You need to have things super dry.  I often dry my work with compressed air before putting it into the cabinet.  Blasting when its wet will clump you medium and make a mess.  You may have to change medium and clean out the suction line. 
6.  There is a learning curve, so work with a fellow artist or take a course to get familiar with the sandblasting unit and the compressor.

7.  Never work tired or under the influence of medicines or alcohol.

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So my final thoughts and recommendations: 
1.  Buy a cabinet/gun and vacuum as a set from a professional sandblasting supplier, where you can get various grits and media and more importantly advice. It will save you time and money!
2.  Encourage bench top cabinet users to use a vacuum and protect themselves from the sandstorm they create.  
​3.  Don't forget to change the oil in the compressor at the recommended time.  
4.  Enjoy this fabulous machine and technique.

 

I would love your feedback. Leave me a comment and I will get back to you. Thank you. To subscribe click on details link at the bottom of this page and a subscription form is available.

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