Well, obviously the reason is that the glass will chip, break, get scratched and otherwise become unusable. The same happens sometimes when the glass is shipped from your supplier, or when it ends up laying around on your work table and someone (maybe you) slides it across the table, or dings a corner by not taking care in handling it.
So what do you do when you lose a perfectly good piece of glass to an edge chip or scratch from careless handling? Three choices come to mind right away. First, you can throw it away and absorb the loss. Second, you can figure out how to make lemonade with that lemon, and third, you can get disgusted and start working with something else entirely. The first choice requires no further explanation, except that it is a shame to waste an otherwise good piece of glass if you could just accomplish choice number two. The second choice is the subject of our next article, where we will show you some great ways of actually using damaged glass blanks to make some unique etched pieces. The third choice is just what we will be talking about in this article: Something else you can etch with your blasting equipment besides glass.
The “something else” we are suggesting in this article is using stone as a substrate, instead of or in addition to glass. Lots of people who etch glass awards and corporate gifts know they can etch on stone, theoretically, but we find that few have tried it. They are afraid that they will contaminate their equipment, that they will need other materials than they keep on hand, or that there are some secret techniques that they don’t know in order to be successful. All excuses!
None of these things are true. You can use the exact same equipment you use to blast etch (and carve) glass, the same abrasive, the same photo resist (though perhaps a thicker version), and stone dust will not contaminate your equipment. The only additional technique you will have to master is how to use a can of spray paint. (We have found in our classes that this is within the capabilities of most people in the awards business!) More on the spray paint later.
In addition to this, what most awards shop owners don’t realize is the vast array of different types of stone products available. All you have to do to convince yourself of this is go down to one of the big import stores, like Pier One or Cost Plus. During a recent visit, we counted no less than 40 different types of stone products that could be etched, including bowls, plates, cups, lamp bases, paperweights, candelabras, bookends and much more.
Then, if you look into the catalogs of the glass suppliers you already have in your supplier file, you will find many more sizes and shapes of stone blanks that are made especially for the awards industry. These include paperweights, bases for etched glass or stone pieces, and small monolithic pieces of flat stone that are cut into interesting shapes that are faceted, ground and polished just like glass pieces used in the same industry.
But these stone pieces all have one thing in common: They are all fairly hard stones that are cut and polished to a high degree. There are many other types of stone that can be etched as well. We have worked on flagstone, sandstone, slate and travertine used for projects from garden path stones to floor tiles. We have worked on field stones used as address stones for individuals and businesses. We have even carved fist-sized river rocks that were tumbled smooth from hundreds to thousands of years of rolling along the river bottom. We have also created many etched awards and plaques of polished marble and granite and full stone awards.
Though there are many similarities between etching stone and glass, there are some significant differences. These differences aren’t nearly enough to provide you with an excuse for not trying out stone blasting, though. So, let’s get into just what are the differences between etching stone and glass and how to deal with them.
TEXTURE AND HOW TO DEAL WITH IT
Glass is a completely homogenous substrate, so when you etch or carve it, the surface (no matter how deep you go) is always smooth and even. The only texture you see is controlled by what size abrasive you use. Not so with stone. Every stone has a matrix of particles of different sizes, different hardness, and different color. What this means is that the deeper you go into stone, the rougher the etched surface can become. The softer and smaller particles of the matrix are eroded more quickly, leaving behind larger particles that appear raised on the etched surface.
The major problem with this phenomenon is that the irregular surface, combined with lines of different color in the matrix, make it much more difficult to see the carved design on stone than on glass. Here’s where the paint comes in. To make the design more noticeable, with higher contrast, you will need to color fill or paint the carved areas of the design.
The first thing that this implies is that you shouldn’t stop at just surface etching the stone, because there won’t be enough depth to hold the paint. Stone is almost always blasted deep enough to be called “carved”, because the recessed surface provides a “dam” to hold the paint, because it helps protect the paint when the stone is cleaned or touched and because the carved design just plain looks better.
The second thing implied by the idea of painting the carved design is that you have to use a good, durable paint of a color that matches or complements the color of the stone. Though some people think there must be a secret type of paint available just for this purpose, it isn’t true. All you need is a good-quality, outdoor-durable, fade-resistant paint like enamel or epoxy. The easy way to paint is to use a spray can, and we have regularly used paints like Krylon or Rustoleum. The more difficult way is to use liquid paint and apply it with a brush or color fill machine (a small paint pump that applies paint through a needle). For this purpose, we have used One Shot lettering enamels or model maker’s paints like Testors.
Much of the painted carved stone in the awards business is painted with metallic colors like silver and gold, partly because they go well on most colors of stone and partly because the colors themselves help convey a sense of elegance and importance to the carved design. However, common sense should be followed even here. It is obvious when you look at the combinations that silver paint goes better on black marble with gray streaks and gold tends to go better on green marble with tan streaks.
You should take particular care, when using non-metallic colors, to match the colors in the stone with the paint. If you are not confident in doing this, take a color class or ask for help from someone whose judgment you trust. (This is the type of thing we cover in our coloring classes and stone etching classes.)
If you are etching glass now, you are most likely using a photo resist of 3 to 4 mils thickness. This is adequate for surface etching to carving moderate depth in glass. However, as we mentioned before, you will almost always want to carve into the stone, and you will quickly discover that stone looks best when there is much more depth than is usually required on glass. This adds up to blasting at a higher pressure and for a longer time than when working on glass. With these conditions, the thinner resists will have a great tendency to come off the surface while you are blasting or for the edges of the designs to become degraded.
This is easily solved by simply using a thicker version of the resist you normally use. Most photo resists are available in 5 or 6 mil thicknesses and some even 10 mils or more. These are tough enough for most blasting you will want to do on stone. However, using these thicker resists means you won’t be able to get quite as fine detail as you get with the thin resists. This is fine, though, because fine detail (thin lines, tiny lettering, etc.) doesn’t show up well on stone because the aforementioned texture of the stone can be so distracting. If you are using a self-adhesive resist, you may also want to consider the addition of a liquid or dry transfer adhesive, especially if the stone is not polished perfectly smooth.
The primary exceptions are 3/16” to 1/2” deep blasting sometimes done on gravestones, cornerstones of buildings (aha! another possible marketâ€¦) and some garden stones. For these projects, we use plotter-cut or laser-cut rubber masking of 25 to 45 mil thickness available in the gravestone industry. We also use these extra-thick resists whenever we want to really crank up the pressure on a particular job (i.e. 60 to 80 psi with a pressure blaster) to complete the job as fast as possible, even if the depth isn’t too great.
We use 180 to 220 grit silicon carbide abrasive for our glass products. We don’t use aluminum oxide because we don’t like the excess static electricity shocks it produces and the fact that it tends to cling tenaciously to the back of the glass you are etching. This makes it much more difficult for light to come through the glass to illuminate the etching so you can check your depth and quality. In almost every case, we just use the same material on stone, especially highly polished stone that requires some degree of detail.
However, if you blast stone regularly, it cuts faster if you use a coarser abrasive. If you can dedicate a separate blaster and cabinet to stone, you should probably consider 80 to 100 grit abrasive for the extra cutting speed. For regular stone blasting with relatively fine detail, perhaps 120. In addition, since you don’t have to look through the material or have light coming through it (yes, that would have to be a very powerful light), you could use aluminum oxide because it is a little cheaper. You would still have the static problem, which is enough for us to opt out and stay with the carbide.
GLASS IS TRANSPARENT AND STONE IS NOT
Yes, yes and the sky is blue and the sun is hot. So what else is that obvious? Obvious it is, but it might take you a few minutes to realize that that simple fact means that you can’t use the exact same artwork and layout on each material. Since glass objects are generally etched from the back and viewed from the front, and stone objects have to be etched and viewed from the front, you have to reverse your artwork when you work on glass, but not on stone. Though this ability is a basic part of most software design programs, the computer operator (that could be you and me) has to remember the difference.
Even less obvious is that this means areas you blast deeper on glass will appear to be coming closer to you, while areas on stone that you blast deeper will appear further from you. If you want to create a carved logo on stone where the letters protrude from the surface plane of the design, you will have to blast the background away and leave the letters unblasted and raised. Areas blasted deeper on glass will not only appear raised but will also appear whiter, while areas blasted deeper on stone will be darker and more in shadow.
Another not-so-obvious effect is that you have the choice of using opaque, translucent and transparent paints to color the etched areas on glass, since light will illuminate the etched design on glass from both back and front. However, you can only use opaque colors on stone since only front surface light will show the etching. If you try to use transparent colors, you will barely notice the color, since the color of the stone will show through so much. On dark stone, transparent colors just disappear.
LAST BUT NOT LEAST: CERAMIC
No discussion of blasting stone is complete without mentioning ceramic. The possibilities of blasting ceramic is something not generally recognized in the awards industry, in spite of the fact that it is so similar to blasting stone. In fact, ceramic is almost like manmade stone.
Ceramic is opaque, like stone; it can be smooth or rough like stone, and it erodes under the abrasive blast much like stone. There are many more similarities between ceramic and stone than between either of those and glass. However, there are two major differences between stone and ceramic when we discuss blasting them. First is the fact that ceramic is generally created with a colored glaze on the surface, and second is the fact that ceramic is much more homogenous in structure than stone.
The importance of the glaze is the extra dimension it gives when you consider that you can either surface etch the glaze (giving a frosted version of the glaze color) or you can simply blast all the way through it (since it is relatively thin), changing the color of the etched area completely. (When you blast the glaze off, the base color of the clay body shows through. This can be white, as with porcelain ceramic to earth colors if the clay body is stoneware.) You can even create designs that have both surface-etched and deep-etched elements, for three separate graphic elements (including the unblasted glaze color).
Even more interesting is the possibility of learning to control your blaster well enough that you can just partially remove the glaze, giving a lighter shade of the glaze color. This will allow you to create adjacent elements of different shades, a much more sophisticated appearance than single-stage blasting. If this wasn’t enough, adding color through painting can add even more possibilities.
Since the ceramic is more homogenous, there is little texture difference in the blasted area as there is with stone, so the need to paint the design to see it is less important. That combined with the obvious color change when you blast through the glaze makes painting the surface a complete option, rather than a necessity as it is with stone.
The primary types of ceramics that are blasted are tiles of all sizes and containers like vases and bowls, lamp bases and the ubiquitous coffee mug. Of these, the coffee mug is the only ceramic product that comes to mind when most people in the awards business think of etching ceramic objects. Tiles are particularly interesting because they can be floor tiles, tiles used in the backsplashes of kitchens and bathrooms, wall tiles and murals, and they are very unique and effective as signage.
If you were providing the etched glass awards for a certain company, you could easily offer to provide custom etched logo tiles for their entryway, a wall mural for the conference room with their logo and company motto, and a tile sign for the front of their building. Just remember how much easier it is to sell more products to an existing customer than it is to develop a new customer.
Working on these types of materials can not only give you a break (pun intended) from working on delicate pieces of glass, the break can be a profitable one. Etched and carved stone or ceramic products are very unique, especially considering that you are easily able to customize them for the person or company ordering the job. Whether created as personal gifts, corporate gifts or awards, they are a profitable new product.
And remember, if you live in a stone house and throw glass, save the pieces so we can show you what to do with them in the next article!
© 2005 Norm & Ruth Dobbins