Some
things really are meant to be engraved in stone, just as the old saying
goes. Offering laser engraved stone products to your customers opens a
wide range of markets such as memorials, desk accessories or decorative
tiles. What makes this form of personalization have such a high perceived
value to a customer? On the top of the list is the permanence of the engraving.
Dating back to ancient times, important documents were engraved into stone
tablets for posterity. The longevity of the engraving was considered crucial
in days of old, and is still thought of in the same way today.
Customers also view stone items as timeless and
make purchases due to the solid feel and weight of the material. Stone
is heavy and has a feeling of quality, elegance and durability
and these features mean value. In our society of plastic throw-away
products, the durability of an engraved piece of stone has worth and appeal
for many years to come.
Stone Varieties
Stone materials that are suitable for laser engraving
vary in quality, color and texture. Many produce brilliant results. Marble
is a common stone variety that can produce highly detailed results. Marble
generally has a very fine texture and is suitable for engraving photos
or detailed text. The color range of marble is one of its benefits. Beautiful
and rich colors like Jet Black, Green, Rose and White make marble popular
with many customers. Hewn from quarries around the world, better engraving-quality
marble comes from India and Pakistan where the marble trade has existed
for hundreds of years.
Slate is another type of natural material that
can produce good laser engraving results. Slate is relatively soft and
sometimes has a very uneven surface. Its a fine-grained, metamorphic
stone derived from sedimentary rock shale. It is uniform in color, and
available in shades such as dark to light green, mottled purple, black,
gray or dark red. Veined patterns from overseas have also recently been
introduced. Unless its surface has been honed smooth, slate can be recognized
by its distinct cleft pattern. Slate tiles are commonly available in several
sizes and are frequently used on walls and floors.
Granite is a stone variety that is dense-grained
and possesses excellent hardness and durability. For this reason, its
very popular for memorial and architectural applications. It is an igneous
rock, which means it was once molten, and formed as it cooled deep within
the earth. Minerals within granite typically appear as small flecks throughout
the stone, creating a salt and pepper look. Other types have
veining similar to marble.
Granite can be highly polished or finished in
a variety of ways. Comprised of feldspar and quartz, granite is available
in a range of common colors including black and red, which are the most
common for engraving applications. The consistency of granite can sometimes
be rather coarse or crystalline and may best lend itself to engraving
applications involving text and graphic designs.
Travertine marble is a variety of limestone formed
in pools by the slow precipitation of hot, mineral-rich spring water.
The holes that are characteristic of travertine are created
when carbon dioxide bubbles are trapped during the stones formation.
Although classic travertine is recognizable by its homogenous ecru or
dark colors, other shades such as dark reds with dark brown veining are
available. Travertine is available in cut and polished standard tile sizes
and is commonly used for flooring and countertops.
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Laser engraving
on stone materials usually provides a white cut. |
Figure 1:
A laser engraved marble nameplate creates an elegant piece that customers
love. |
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Sandstone,
as the name implies, is comprised of fine sand particles bound together
by natures own concrete-like glue to form this uniform stone product.
The color of the sandstone is created over the course of time by minerals
being washed through hardened stone. Sandstone is somewhat brittle and
has a coarse quality due to the embedded sand mixture. Laser engraving
results can be very good as the stone can be very flat and is relatively
soft in density.
River
rock is another stone type to consider for laser engraving. Engraved river
rock has found its way into markets such as corporate gifts, gardening
and even as pets for some folks. When referring to river rock, were
talking about actual stones from river beds that have spent centuries
becoming smooth, rounded and polished by flowing water. These sedimentary
stones are comprised mostly of sand and will engrave with a medium to
coarse quality. The more ideal types of river rock are those that are
darker in color with a highly polished, flat surface. A sprayed-on clear
coat can also help to create a smooth surface for laser engraving.
Shallow Engraving
Several
options are available for laser engraving on stone, and all can achieve
very good to excellent results. While considering each of the processes
to work with, keep in mind that the base material is stone. While not
trying to overstate the obvious, stone varieties are natural materials
and can vary greatly from one example to the next. These materials were
created by heat and pressure over millions of years and no two pieces
are the same. Our goal in this article is to educate you on the materials
and processes so that you can make knowledgeable adjustments to achieve
professional results.
The
best you can ask for with most stone products is to have a level of consistency
from a supplier that reduces the variables slightly. Many suppliers can
presort the finished goods into similar or like product groups to achieve
a level of consistency in the products they ship you. Even with the presorting
of finished products, color and size will vary and should be considered
in the engraving process.
The
easiest process for laser engraving stone is to simply focus the laser
beam on the top of the stone and engrave as you would on acrylic or wood.
This style of direct engraving can best be described as a bleaching process
where the laser energy whitens the stone during engraving. During laser
engraving, the color embedded in the stone will be removed to reveal a
white color. The laser engraving system will effectively remove the color
of the stone that took millions of years to filter in. The depth of engraving
from the laser will not be deep; in fact, it is often barely perceptible.
That does not mean the engraving will look poor, though. Highly detailed
photos and text can be laser engraved onto stone for truly professional
looking results.
One
of the keys to achieving crisp, clear engraving quality is to find the
correct power and speed settings for your laser system. Keep in mind that
the recommended power settings in your laser system manual are just a
basic starting point. Optimize your settings by test engraving on a similar
sample of stone and examine the results. One common error is using too
much power for engraving on stone. This results in engravings that look
unclear or blurry. The laser can develop enough heat energy to start to
crystallize the stone and fuse particles together. Conversely, using too
little power will yield results that are gray instead of the desired white.
Running the same job a second time may clear up the engraving quality
to a whiter shade. However, adding more power in increments of 5% until
the ideal setting is found is a more permanent solution.
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Figure 2:
Paint filling allows you to add practically any color to the cut. |
Figure 3:
A sandblasting stencil is easily created by lasering through pressure-sensitive
polyester. |
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Direct
laser engraving will create a white engraving color in contrast to the
base color of the stone. The natural stone may have some white veins or
streaks that run through it, causing some readability problems. Since
the vein color is usually white and the engraving is white, the effect
of engraving over the top of one of these veins will look like the engraving
has a lightning bolt running through it as the vein blends into the engraving.
Positioning the engraving so as to not interfere with the vein is the
best solution in this case.
Need
to add some color to the engraving on the stone? Consider a color fill
process that is made easy using the laser. When working with highly polished
stone materials, the color fill process starts with the direct engraving
of the stone. The direct engraving of the laser has broken the top, polished
surface of the stone and left an engraved area that is now porous and
will soak up the color fill material. Recommended color fill products
are ones that are lacquer based, not acrylic based. The acrylic-based
color will float on top and not soak into the stone like the lacquer-based
materials. Typical colors for adding to laser engraved stone are gold,
silver and copper. The ideal product would be an ink-like product.
Using
a small paint brush, dab the color on to the engraved area, allowing it
to soak into the engraving. While the color is still wet, wipe the area
with a soft, clean cloth. Any residual color can be wiped clean with a
soft cloth and mineral spirits. The results of adding color can be outstanding.
It can add the brilliance and clarity to engraved stone products that
customers are willing to pay for.
Note:
This description of color filling is greatly oversimplified, and color
filling is also useful for many other materials besides stone. For these
reasons, Ill be taking a more in-depth look at color filling in
one of my upcoming articles.
Deep Engraving
Creating
deep engraved areas in stone can be accomplished using a laser system,
polyester sandblast masking and a sandblasting system. Start by applying
a laser-safe, polyester mask to the stone. Now you can use your laser
to engrave through the mask and into the stone, creating a stencil or
mask for sandblasting. After laser engraving the stone piece, you are
ready to sandblast to the desired depth. Most of the stone types we have
discussed in this article are relatively soft and can easily be sandblasted
to a depth of 1/4" or more using a quality polyester mask.
Ready
to add color to your sandblasted product? After sandblasting, clean off
the stone with some compressed air. It is now ready to be spray painted.
Apply a smooth, even coat of high-quality spray paint to the clean area
and let it dry. Be sure to leave the mask in place to make cleaning up
after painting a breeze. Simply remove the mask and clean up any excess
paint.
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Figure 4:
Lasering a photograph onto black marble is easily accomplished. |
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Engraving Photos
on Stone
Photo
engraving is one of the fastest growing segments of the laser engraving
industry. The ability to put a treasured photo onto stone using a laser
is a proven process. Proven to generate more sales, that is!
Like
any digital process, laser engraving photos should start with a decent
quality photo to scan. The process begins by scanning the photo at the
dpi that you intend to engrave with. Typical engraving dpi settings are
500 or 600, depending on the laser system you have. Scan the photo as
a grayscale bitmap format in the correct dpi resolution. Using Photoshop,
a program developed specifically for lasering photos, or Corels
PhotoPaint, scale the photo to the final engraving size using the resample
tool. To add some professionalism to the engraving job, add a featheredged
vignette or drop out the background behind the subject using some of the
basic tools in the program.
The
image is now ready to import into PhotoGrav software for processing. PhotoGrav
software offers many advantages for laser engraving photos on to all sorts
of materials, including stone. PhotoGrav can compensate for marginal-quality
photos by automatically creating a histogram, which it uses to compensate
for contrast and density failures in the original photo.
Another
automatic feature of the software is called edge enhancement. This is
particularly helpful with materials like stone when the subject has a
tendency to blend into the background. The automatic edge enhancement
feature provides a little more contrast around the edges to make the subject
more pronounced.
Using
the PhotoGrav software is easy. Its just a matter of opening the
grayscale bitmap scanned image and selecting the material to engrave on.
A dropdown menu lists dozens of commonly found engraving materials and
each one has unique settings to make the engraving process more accurate.
Select the Black Marble setting for engraving on stone products.
Click the AutoProcess button and let PhotoGrav do its magic.
When
the process is complete, save the Engraved Image in a folder
on your computer. I keep a folder on my desktop called Engraved Images
to make the files easier to find. The Engraved Image is what will be imported
into CorelDRAW or your current layout software and then printed to the
laser, along with any text or other graphics that will be incorporated
into your layout.
Multiple
Markets for Stone
Laser
engraved stone products cross over into many different markets. Flooring
is certainly one market. The ability to create custom floor designs is
one that many distributors of floor products would like to know about.
Gaining in popularity today are the so-called donor floors
or walks of fame, used to recognize or commemorate people
or organizations.
Commercial
and residential designers and builders also need to create custom products
for their customers and could be a market for laser engraved stone. Memorials
for people and pets continue to be a growing market and one that is neither
price sensitive or subject to consumer market swings. Many corporate premiums
and desk accessories are made from marble and fit the corporate customer
need of looking different or upscale to impress
customers.
Of
course, these are just a few marketing applications for engraving stone
products. With your laser engraving machine, some stone and a little imagination,
the sky is the limit!
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