Hello, my name is Swann Rack and this is guide how to make a DCG Hologram, DCG standing for
dichromate gelatin hologram. Enjoy.
Step 1. Checking the glass:
The first step when making a hologram is to check the glass. Glass is made in a factory
by pouring molten glass on a bed of molten tin. Glass has a lower density than tin, so
it floats on top. That’s why it’s called float glass. The floating glass forms an almost
perfectly flat surface on the molten tin. Molten tin is also colder than molten glass.
So glass cools down when it touches the tin. New glass is constantly poured at the beginning
of the production line, so the older glass is getting pushed forward. This pushing motion
forms a pattern of parallel lines in the glass. You can make this pattern visible if you shine
an expanded laser beam on the glass at a very steep angle and look at the light passing
through. Depending on the orientation of the glass, you will see one of two different patterns. You
will either see a pattern of parallel lines or when you turn the glass 90° degrees you
will see a wood grain pattern. To get the optimal hologram, the glass should be oriented
so you see the "parallel lines" pattern. If the correct orientation of the glass is
neglected, there will be scatter in the final hologram. With a pen you can draw an arrow
on the glass, indicating the direction of the pattern. When you cut the glass a little
longer in the vertical size than in the horizontal, you will be able to remember in which direction
the lines were running.
Step 2. Cutting the glass:
I use standard float glass for making holograms. Optical-grade glass doesn’t yield better
results. First I draw a sketch of how I want to cut the glass. As you can see there is
an arrow on the glass indicating the direction of the parallel-lines-pattern that I checked
for under the green laser light. I will cut my plates a little taller than wide. That’s
how I can remember how the pattern is oriented. In this case I am cutting plates sized 21cm*14cm.
The glass thickness is 2mm. I use kerosene and a brush to lubricate the glass at the
cut-line. I am using kerosene instead of other oils because it quickly evaporates and leaves
little residue. I take a glass cutter and cut the glass in a sweeping motion applying
constant pressure. While cutting you should here a clean hissing sound. The cut puts stress
on the glass. The kerosene fills the cut and keeps it open. As time passes the glass "heals",
so you should break the glass quickly after cutting. Always make the shorter cut first.
To get the best cut possible you always want to cut the glass plate in halves. If your first
cut failed because you released pressure half way through the cut, you can always turn the
glass around and try again. I place the brush handle under the cut and lightly press down
on both sides my hands. This should yield a clean break of the glass. Once all the plates
are cut I check them for imperfections or big scratches. These are most easily observed
by shining through the glass with a red LED light. Don’t throw away scratched glass
plates. They can still be used as cover plates later on. About 30% of the glass you buy won’t
be good enough for making holograms. On a side note you always want to work with
thickest glass still acceptable for your project. Thicker glass is easier to handle and performs
better later on in the process. Step 3. Cleaning the glass:
The glass should be cleaned very well. If any dirt remains on the glass, you get an
uneven coating later in the process. In the first stage of cleaning I use warm water and
some window cleaner to get all the dirt and kerosene off. Next I place the glass into a tank of
hydrochloric acid. The concentration is about 3% acid in water. The glass will stay in this
tank for at least 20 minutes but not longer than 12 hours. If the glass stays in the tank
too long an oxide layer will form on the glass, making it harder for gelatin to stick to it.
After 12 hours I take the plate out of the acid tank and scrub it with a very soft sponge
and dishwashing soap. I Scrub it from left to right and in an up and down motion.
When scrubbing, you will notice that one side of the glass feels a little rougher than the
other side. One side will provide more friction when scrubbing it and also make more of a
squeaking sound. This is again due to the manufacturing process
of the glass. The rough side is the one that had contact to the molten tin. The gelatin
sticks better to the rough side of the glass, so it’s the side that should be coated.
To remember which one is the rough side, you can store you plates tilted at an angle of
30° with the rough side always facing down. This also gives you the advantage that in
case any dirt or dust settles on the plate it will go on the top side of the glass while
the good side stays clean. After scrubbing I rinse the plates with deionized water. This
water is free of minerals and will leave no residue when drying. I put the
wet plate into a drying cabinet, which is at least 30°C warm. There is also a dehumidifier
in the cabinet to speed up the drying. The air in the cabinet should be filtered so no dust
settles on the plates.
Step 4. Preparing the gelatin:
This is how I mix the gelatin that I will use to coat the glass. My formula today is:
367g of water, 68g of gelatin and 8g of Ammonium Dichromate. This is a lot of dichromate and
gelatin and will yield a rather thick emulsion, this recipe is optimized for using a low power
green laser. If you do have access to a blue laser you would want to make a rather thin
emulsion because then more light can penetrate the emulsion giving you a brighter hologram.
Then your emulsion should be 500g of water, 21g of gelatin and 2g of Ammonium Dichromate.
Also if you add 9 drops of Kodak PhotoFlo to that recipe you will get a cleaner more even coating.
The dichromate will be added in a later step, so for now it’s just gelatin and water.
The gelatin is very important for the final outcome of the hologram. I have tried many
brands, but in Germany the best gelatin you can get is Gelita Non Plus Ultra 220 bloom. The bloom
number refers to the hardness of the gelatin. 220 bloom is a rather hard gelatin for making
holograms. The perfect working environment for making
DCG holograms is 24°C room temperature and about 60% humidity. Warmer temperatures will
make your holograms redder. Colder temperatures will make your holograms greener. In the summer
time or when you coat very large plates you should increase the percentage of gelatin
in the water. This will make your coatings thicker. Nevertheless I use my gelatin-formula all
year around. I put 367g of cold water into a beaker. While
stirring with a whisk I slowly pour 68g of gelatin powder into the solution. After a
few minutes the gelatin will get very thick. Now I place the beaker into a water bath.
I use an electric canner for that, because it can be set it precisely to a certain temperature.
The temperature of the water bath will slowly rise to exactly 40°C. If you accidently heat
the gelatin above 50°C throw it away. High temperatures damage the structure of
the gelatin and result in a bad coating. Keep the temperature at 40°C and stir the gelatin
every 5 minutes for a total time of one hour. After one hour the gelatin will have dissolved
completely and will have turned into a honey-like solution. Take the beaker out of the water
bath and let the gelatin rest for 12 hours.
Step 5. Sensitizing the gelatin:
After the gelatin has cooled overnight for 12 hours, I’ll put it back in the water
bath and heat it up to 40°C degrees. Next I set up my small glovebox that I built for
measuring the Ammonium Dichromate. Ammonium Dichromate is a very toxic chemical
and shouldn’t be inhaled. It’s most dangerous when it’s in powder form, because then the
particles can get airborne. I have built an airlock into the box to safely transfer the
beaker with gelatin in and out. I put my hands into the gloves and open the storage container
for the chemical. With a spoon and a little electronic-scale I measure 8 grams of ammonium
dichromate and fill it into a little glass bottle. As you can see the space in the glovebox
is very cramped, so I first measure the powder and then in a second step I put the powder
into a beaker. For that I reopen the airlock and bring in the beaker with the warm liquid
gelatin. I remove the tinfoil dustcover and pour in the 8 grams of ammonium dichromate.
I remove the beaker from the glovebox and put it on a magnetic stirrer on low setting and low
heating for about 10 minutes. Because the ammonium dichromate is now mixed with the gelatin it
is much more safe to handle because particles are less likely to get into the air.
The next step is to filter the gelatin. For that I use the cheapest “Aldi” coffee
filters. I have tried the more expensive filters as well, but they tend to rip and don’t
yield better results. It takes about 15 minutes for the gelatin to pass through filter and
flow into the transparent cup at the bottom. While the gelatin is inside the filter holder
it tends to cool down very quickly making it harder to penetrate the filter. So for
thermal insulation I put a tinfoil cover on the holder.
From the transparent cup the filtered gelatin is poured into a special coating bottle. It’s
a squeeze bottle that can hold about 400ml of gelatin. It has a spout at the top which
is connected by a tube to the bottom of the bottle. When you squeeze it, the bubble-free
gelatin from the bottom of the bottle gets forced out first. At the bottleneck I have
drilled a small hole. By placing my finger on the hole while squeezing the bottle I can
control the flow of the gelatin. When I am finished coating I make sure, to first remove
my finger from the hole and then unsqueeze the bottle. Otherwise the air would reenter
the bottle through the spout creating even more bubbles. In a final step the filled coating
bottle is placed into an ultrasonic bath for about 1 minute to get rid of even the tiniest
bubbles which would make a bad coating. When switching on the device all the bubbles rise
to the top. Now the gelatin is ready for coating.
Step 6. Coating the glass:
For the purpose of coating the glass plates I have built a second glovebox. It’s actually
a dumpster turned upside down with an acrylic glass front and an airlock attached to the
side. I take a warm clean glass plate out of the drying cabinet and place it together
with the coating bottle inside the airlock. The glovebox guarantees a controlled coating
environment that is dust free. The temperature inside the box should be at 24°C and 60%
humidity. The higher the humidity and air temperature, the faster everything reacts
and everything gets harder to control. I put on the gloves from the glovebox and
pull the plate inside. The clean glass plate is placed into the little tray to catch any excess
gelatin dripping down during the coating. My plates will be veil coated followed by a 5 minute
spin on a turntable. With my left hand I hold the plate on the upper left hand corner, while
having the coating bottle in my right hand. I squeeze the bottle while closing the small
venting hole at the top with my right index finger. Once gelatin starts pouring out I
begin coating in the bottom left corner of the plate, move up the left side, then along
the top and then back down again on the right side.
All this is done in one continuous motion. The flow of the gelatin should look like a
“veil” coming down. Once the plate is completely covered, I place it on the spin
coater. It’s an old record player spinning at 80 rounds per minute. While spinning the
plate it rests on 3 spacers made from a cut garden hose. The centrifugal forces will even
out the gelatin. After 1 minute I will turn on a 150 watt infrared light that hangs above
the turntable and leave the plate spinning for another 5 minutes.
The heat from red light is drying the gelatin. The bulb is hanging 13cm above the plate and
15cm off the center axis. Otherwise all the light would be too concentrated in the middle
of the plate. Once the plate is coated I’ll take it out of the glovebox and put it into
another drying cabinet. It should stay in there for at least 12 hours before being exposed.
The temperature inside the drying cabinet should also be at 24°C and 60% humidity.
The slower the plates are drying the better. The door of the cabinet is left open to ensure
good air circulation and to not trap any moisture which would result in a milky looking hologram.
Step 7. Building the exposure setup:
I start by sharpening and flattening the nails on a grinder. Most nails that come out of
the factory are wonky. The nail tip should be very pointy and the nail head has to be
as flat as possible. These nails will be the feet of the exposure setup.
It all relies on the 3 point contact principle. With three points of contact there is no room
for wiggling and you get the most stable system. My model is a 3d silver print of a woman.
The model is glued to a small brick. The brick is spray-painted glossy white for better reflection
and has already 3 spacers glued to the top side.
The gluing of the feet is done with epoxy resin to insure a very stable bond. I mix
part A and B on a piece of glass so there is no dirt getting in. Then I thoroughly mix
it and quickly glue the nails to the underside of the brick.
The exposure setup is very simple. The laser passes through a rotatable polarization-filter,
gets redirected by a mirror and then expanded by a concave mirror. The model is placed on
a solid concrete table resting on inner tubes. There is no need for a super expensive optics
table with Newport legs. Inner tubes do a superior job. By holding a little nail into
the expanded laser you can determine at what angle the light is hitting the model. Like
with a sundial you can adjust it so the light is coming in correctly. The plate will be
exposed Denisjuk-style with the reference beam coming in between 45°-56°. You can
use a protractor to check for the correct angle.
Step 8. Exposure:
To maximize efficiency I coated the plates in the biggest size possible. Now I have to
cut them up. First I recheck the coating job and the glass
quality. Sometimes it’s necessary to clean the uncoated side with window-cleaner. For
this hologram I have coated very thin glass. Its only 2mm thick. I have prepared a little
board to assists me in cutting the plate into four separate pieces. On the board I have
glued strips of duct tape that act as spacers for the cutting job. Without the duct tape
the glass would break in undesired areas during cutting. The emulsion side touches the duct
tape and gets damaged by it, but as long as this is happening only on the outer perimeter,
that’s ok. I place the brush handle under the glass, apply pressure on both sides and
thus facilitate the break of the glass. In a light-tight box I transport the plates
to the exposure room. In the exposure room the humidity should be at 60% and the temperature
at 24°C. I put the plate emulsion-side-down on the exposure setup. Next I put masking-tape
around it on the upper side of the plate. This is done to avoid internal reflections.
The emulsion won't be exposed where the tape is covering it. After the exposure the tape
is removed and one can see the difference between the taped-off-unexposed-areas and
the exposed film. The exposed gelatin will be slightly tanned. Depending on the length
of the exposure this tanning will be stronger or lighter.
With a brush I paint the spacers black so they won’t create unwanted reflections in
the hologram. I use acrylic paint for that. You could also use oil paint, which won’t
be dry by the time of the exposure, creating movement and thus making the nails invisible
in the hologram. I use strong neodymium magnets to fixate the plate to the metal spacers below.
The shiny magnets are covered with masking tape so they don’t scratch the glass. The
trick will create a very stable recording setup.
DCG is very forgiving to overexposure. One can expose ten times longer than actually
necessary and still get a good hologram. Perfect conditions for making DCG Holograms is warm
and dry. You want the humidity to be around 60% and the temperature at around 24°C. The
room temperature is the key factor. The colder it gets the harder the gelatin becomes, and
the more light-power you need to make the hologram. Below 10°C it becomes very difficult
to shoot DCG holograms at all. By the way in the first minute of the exposure
you can move the beam without a problem. As long as you don’t move the table it’s
all good and you can get away with a lot. In this setup the exposure is done with a
100mw green diode laser at a wavelength of 533nm. But I would much rather use a blue
laser, because DCG is ten times more sensitive to blue light.
The laser passes through a shutter and then through a rotatable polarization filter. This
filter can be turned until the light is perfectly polarized. You want to turn it, until you
see the least reflection bouncing of your glass plate and the most light passing through.
The plate is exposed for 4 minutes and then left in the dark for 5 minutes. This is called
the dark-reaction and can be extended up to 3 hours, which can increase the brightness
by about 10%. If you want to make a master of a not so stable
object, you can underexpose the plate by 30%-40% and then let the plate rest afterwards in
the dark. Come back after week and develop the plate, and it will turn out just as bright
as a sufficiently exposed hologram.
Step 9. Developing:
Five Minutes after the exposure I come back into the room. I remove the magnets and take
the plate off the setup and then I carefully remove the masking tape. I walk to the developing
area and place the plate into the fixer bath. All the baths have a temperature of 24°C.
I would highly recommend to wear a respirator with active charcoal filters when working
in the developing room. Also very good ventilation with a fan is very important.
For fixing I use Tetenal Superfix. The dilution ratio is one part fixer and three parts of
water for a total of four parts. One could also use Kodak professional fixer, but I don’t
have any experience with that product. I tilt the tray until all the liquid accumulates
in one side of the tray, I then put the plate inside and level the tray again. A continuous
wave of fixer will flow over the plate. You have to rock the tray constantly for the chemicals
to get everywhere. I watch the plate and observe the slow disappearing of the dichromate-yellow
starting from the center of the plate outwards. The total time the plate should remain in
the fixer is highly dependent on the age of the film and how fresh the fixing solution
is. The emulsion on this particular plate is very young, so I keep it in the fixing
baths just until all the yellow is gone. If the emulsion would be older, I would take
it out when it’s still slightly yellow. In this case the fixer is super fresh, so
I fix the plate for under 30 seconds. Holding the plate on the sides, I proceed
to the washing bath. The plate is supposed to be dropped in the bucket. It contains just
water and is intended to remove all the residue fixer from the plate. Depending on the plate
size I keep it inside the bucket for at least 1 minute and up to 20 minutes. I slowly pull the
plate out of the water in one continuous motion.
In the next steps the plate will go through a series of four isopropyl alcohol baths of
increasing concentrations. It’s 54%, 59%, 84%, and 100%. This process will gradually
replace all the water in the emulsion with alcohol which will then evaporate after the
final bath. I immerse the plate quickly into the 54% alcohol bath. Bigger plates are just
dropped into the tank and depending on the size left in each bath for at least 45 sec
and up to 4 minutes. Today the plate is very small. Such a tiny plate is good after about
25 seconds in each bath. When I pull the plate out of the 54% alcohol
the gelatin will be very soft and gooey. I hold it upright in front of me for about 25
sec and watch how the gelatin reacts to the air. The alcohol will evaporate slowly from
the edges towards the center. I don’t want the alcohol to dry off completely. If I let
that happen the gelatin structure will collapse. The alcohol should evaporate to the point
where the emulsion is barely wet and almost starting to dry. You know this point has been
reached, because at the top of the plate the gelatin will look like snake skin. Once I
see that snake skin I lower the plate slowly into the next bath. Going from 54% alcohol
to 59% is a critical step. The plate will remain another 25 seconds in the 59% alcohol
bath. Inside the tank the emulsion will turn from gooey to solid.
Coming out of the 59% the gelatin will have become rigid, it’s now closer to being a
solid than a liquid. When I take the plate out I will watch for the snake skin.
Once I see it I slowly immerge the plate into the 84% baths where it will remain another
25 seconds. After I have taken the plate out of the 84%
bath and wait a while I will start to see a hologram reflection at the top of the plate.
Once I see that slight reflection the plate is ready for the final bath. The 100% alcohol
bath can be heated up to 40°C. But today it’s unheated and at room temperature. I
put the plate smoothly into the 100% and it will stay in there for 3minutes.
I take the plate out of the last bath and quickly move to the drying area. The room
temperature in the drying room should be above 30°C and the humidity below 20% or lower
if possible. The plate is dried with a paint-stripping
gun set to the lowest blower-setting but on maximum heat. With this tiny plate the drying
motion is not relevant, but if the plate is larger you would want to concentrate the heat
on the lower part of the plate first, then going from left to right and up mimicking
an L motion. Because gravity assists in the drying, the most part of alcohol will concentrate
in the lower part of the plate. After a while turn the plate 90° counterclockwise and continue
the drying. Someone once told me that you can not over-dry
but you can under-dry a hologram. This is true when using a hairdryer. But if you use
a paint stripping gun, you can over-dry and even burn the gelatin if you leave the gun
too long in one spot or move it too close to the emulsion.
After some time performing the L-Motion you can concentrate the heat on the middle of
the plate blowing in circles. The plate will become milky at first before turning transparent
again. The Hologram should appear after 2 minutes of drying. Once I see it, I continue
to dry it for about another 3 minutes. When the hologram is finished I put it in a plastic
airtight storage container. Inside this container I have also placed a little cup filled with
silica gel. This gel is a drying agent that will bind any remaining humidity. I can store
the holograms in the container indefinitely but I highly recommend to seal them quickly.
Step 10. Scraping:
For this demonstration I will use a different hologram than the one I just developed but
the process is identical. I highly recommend to wear a respirator while scraping. You want
to protect yourself against the alcohol fumes as well as particles of dichromate gelatin
that you scraped off and that are floating in the air. Be careful that no condensation-water
from the outlet of your respirator drops on the hologram, which would ruin it. I turn
the holographic-plate so I can write on the uncoated side.
At the top of the plate I put a piece of garden hose that acts as a spacer because I don't
want the emulsion side to touch the table. Normally I also put a towel on the working
area so the hologram doesn't get scratched, but I forgot it this time. With a pen I frame
the hologram. Everything outside of this frame will be scraped away. It helps to define the
vertical and horizontal centerlines first and then draw a frame around them accordingly.
When I am finished I turn the plate again so the coated side is facing me. Now I will
begin with the rough removal of the gelatin. I take a damp Sponge and move it over the
edges of the plate. The sponge will wet the hard gelatin and make it more easily removable.
I leave a 5mm safety gap between the marked-outlines and the sponge-damped area.
With a razor blade I remove the excess gelatin. This process is repeated four times for every
side of the hologram. Now for the precision work: I have attached two clamps to my steel
ruler so it's angled at 45°. This way the ruler can’t damage the emulsion by touching
it. I take a cotton swab and spray it with 100% isopropyl alcohol and move it over the marked
line. I place the ruler half a millimeter next to this line and cut the emulsion with
the pointy edge of a new razorblade. With the flat side of the same blade I take off
the emulsion. I repeat this process 4 times for every side.
Now I prepare for the final cut. Once again I swipe the emulsion with a cotton swab dipped
in alcohol. I use a new razor blade and cut the emulsion on the marked line. With the
flat part of the razor blade I take off the final strip. By leveling the razor blade flat
and hitting the cut in a knocking motion I can remove even the smallest residue of gelatin
from the plate. I repeat the cut four times, using a new razorblade every time. The result
should be a perfectly smooth edge. The hologram is now ready for sealing.
Step 11. Sealing:
The hologram has to be sealed, so the emulsion is protected from outside moisture. DCG is
very hygroscopic and sucks the humidity right out of the air. This causes the emulsion to
swell, which collapses the fringe structure and makes the hologram invisible. It can be
made visible again by redeveloping the plate, but by properly sealing it in the first place,
this is not necessary. First I prepare the tools that I will need
for sealing. I heat the rim of a small plastic cup and with a nail I form a little spout
at the top. This will make the pouring of the glue much easier. The Hologram should
be sealed in a dust free environment. Otherwise there will be specs of dust glued onto the
emulsion. To avoid this I am working inside a laminar flow bench that I have built myself.
You can see a wall of straws, blowing air towards me. This guarantees that no dust can
enter the work-area. I wear a respirator and gloves and even take a shower before sealing
so no dandruffs can get on the hologram. First I mix the two part epoxy glue which
I will use for the sealing. UV-glue can be used as well but it has a tendency to yellow
over time and generally makes for not as strong of a bond as epoxy glue does. The epoxy glue
consist of part A and B. The instructions for my brand of glue are 12g of resin
and 6.6g of hardener. Today I am using a budget glue, but if you have a hologram that you
really want to seal forever I recommend the product HXTAL NYL-1. This is a special epoxy
glue which is mainly used in museums for archival purposes.
I stir the glue for some time above the heat gun, set to the lowest setting. Warm glue
mixes much better than cold glue. If you want to get really fancy you could also place the
cup in a vacuum degassing chamber. That will get rid of all the bubbles that you created
during mixing. Sadly these are expensive so I don’t have one. With a photographers-lens-dust-blower
I blow any possible dust off the hologram. With the heat gun set to the low setting I
blow over the plate and warm it up. Warm glass bonds much better with the epoxy-glue.
Next I have to choose a piece of glass that will cover the plate. This cover-plate should
be about 3cm bigger on all sides than the hologram you want to seal. There should be
some overlap as a safety margin when gluing two pieces of glass together. The cover glass
will be cleaned and dried in the same way I demonstrated before in my cleaning glass
segment. I don’t recommend to glue glasses of different thicknesses together, as this
will decrease the longevity of the hologram. Glass of varying thicknesses will expand and
contract in different ways and thus work against each other, weakening the epoxy bond over
time. I pour the glue on the hologram. The shape of the poured glue should look like
a T with two legs. I try to avoid making any bubbles. Once the glue has been poured on
the glass, I blow with the heat gun over the hologram. This will heat up the glue which
will make it more fluid and at the same time pop most of the bubbles in it.
From the drying cabinet I fetch the cover-plate. I lower the plate very slowly and then rock
the glass around a little so the glue disperses all over. Very slowly I tilt the top cover
plate and lower it towards the bottom hologram plate. You really want to this is in the slowest
way possible, because if you do it fast there is a high chance of creating new bubbles.
If everything works perfectly the glue should move from inside out, covering the entire
plate. Next I bring the glass sandwich to a different area where
I let it cure. I put 4 cinder-blocks wrapped in saran wrap around the sealed hologram.
I want the least surface area from the blocks to touch the soft glue, so I only make them
touch with corners. The cinderblocks will prevent the cover plate from sliding off and
because they touch the plate only with the corners I will able to remove them easily
once the glue has hardened. It normally takes at least 24 hours for the epoxy-glue to cure.
For a tighter bond the curing should be done in a warm place.
In a final step I put a weight on top of the hologram. The weight is removed after one
hour, it’s just there to apply some initial pressure on the glued-glass-plates. If the
weight is left on there for too long there will be visible force lines in the final hologram.
After about 12 hours the glue is sufficiently cured to bond both glass plates together but
still soft enough to be peeled off. Big droplets of glue that have formed on the underside
of the hologram should be removed now. With the help of a little isopropyl alcohol and
a razor blade this works quite well.
Step 12. Grinding:
The hologram is finished and sealed at this point. Now it's all about grinding off the
sharp edges from the glass making the hologram more safe and presentable. There are machines
that grind perfect edges on glass plates. If you don’t want to do this yourself you
can give the hologram to a workshop and they will do an amazing job. Nevertheless
I will demonstrate a very low budget approach to grinding glass that can yield some very
nice results. The machine I am using is a Kristall 1 Glass
grinder with interchangeable grinding bits. I highly recommend wearing safety goggles
for this work, as tiny shards of glass are constantly flying in your face while grinding
the edges. A respirator is also advisable so no glass dust can get into your lungs.
I forgot to do it this time, but normally I cover the entire front and backside of the
hologram with tape, leaving only the edges exposed. This will prevent the surfaces from
getting scratched. Prior to grinding and only if deemed necessary
you could cut the sides of the hologram with a rotating tile saw. This only makes sense
if you need to take off huge chunks of glass that would take forever to grind off. When
using a tile saw it’s a good idea to leave a 5mm safety margin between your cut and where
you want your final edge to be. Always keep in mind that the wider the rim between the
emulsion and the actual edge of the glass, the longer your hologram will last. The humidity
in the air will eventually destroy every DCG hologram, but the wider the rim the more distance
the moisture has to penetrate before it can reach the emulsion.
When grinding the glass you always want to grind the top and bottom edges first while
holding the glass plate at a 45° angle towards the grinding bit. This is called
chamfering and will create a triangular shape. Only in the final pass will you level the
plate by pressing it flat against the grinding bit, taking off the tip of the triangle. This
will prevent the glass from chipping. The grinding-bits on this machine can be changed.
First I start with a very rough bit and then work my way down to the finer bits. In total
I have 3 bits. They are all color coded. The roughest is easily recognizable. The middle
one is orange, while the finest bit is blue. With each bit I grind every edge multiple
times until it looks nice and is smooth to the touch. For a plate this small the grinding
takes about 90 minutes. After the grinding is complete the Hologram
is finished and the final step is to remove all the protective tape from the top and bottom
side. Any residue from the tape can be easily removed with isopropyl alcohol.
Closing words:
Holography is my life’s passion and I have dedicated an enormous amount of my time to
it. I spent eight years working with DCG and was really difficult to get all the information
that I put together in this video. I wish someone would have given me this information
when I started out. That’s the reason why I made this guide. Finally I want to show
you a video of the best hologram I ever made. The object is a 3d model of a stairwell I
designed in a 3d-software and 3d-printed in silver. I am sitting on a dyke in my hometown
in Hamburg, Germany flipping it through my fingers. This hologram combines everything
I love about holography. The colors and the depth, a crystal clear glass plate with a
3d image that seems impossible but looks so very real. My dream is to one day make a hologram
just like that but two meters high and one meter wide and then put it somewhere in the desert.
Conclusively I want to thank my brother Miro
and my friend Stefan for helping me to make this video. Thanks a lot guys.