The Amethyst Geode Bookcase

Prospero's Amethyst Geode Bookcase

For our production of Shakespeare's The Tempest in Winter Semester, 2013 at Brigham Young University-Idaho, I designed an amethyst geode bookcase for Prospero to keep his magical tomes.  I thought it would be magical for a magical show.

I wasn't sure we could pull it off, so I came into the shop and created a prototype.  In about twenty minutes I had created and placed about twenty-five crystals.  I took it to my friend in the geology department and showed him.  He said it looked like a cluster of quartz crystals, so I knew it would work.  I pointed out to him that quartz crystals were hexagonal and my crystals were octagonal.  He reminded me that the audience was going to be thirty feet away and no one was going to count sides.

Process
The process begins with 2" blue foam.  I used shop scraps so this technique was essentially free.  The blue foam was cut into different sized strips and then cut into blocks on a bandsaw.  There is no need to measure.  Just do it.  No crystal in a geode is exactly like another.  They are all different sizes and the faces line up somewhat differently depending on how and when and what conditions the crystals were formed under.

There was a garbage can placed behind the bandsaw to catch the blanks as they were cut.  This process took two full garbage cans to complete.  It doesn't matter if the foam is broken up, in fact it creates more realistic crystals if a few of them are "broken".

Foam blocks on the bandsaw

Garbage can full of crystal blanks

Shaping
The blanks are then taken to a belt sander to be shaped.  It is important to wear eye protection, ear protection and a particle mask when you cut and shape the foam.

Before you attempt to create crystal shapes, it is a good idea to research exactly what crystals look like so you can replicate them as closely as possible.  When you are shaping the crystals it is also important to be focused on your task and think through each crystal face as you cut it.  As soon as you start cutting on auto-pilot it's time to stop and have someone else take over.  Your crystals will all start to look the same and you will shave off your fingerprints.

The first step in shaping is to cut the sides of the crystal.  First knock the corners off so you have an eight sided barrel shaped piece of blue foam.  Quartz crystals are six sided but the foam pieces in this process are eight sided.  This isn't really a problem, it's just something to keep in mind as you cut.

Make sure you hold the foam tightly as you sand and cut.  This material has a nasty habit of catching on the sander and jettisoning out of your hands.  If you aren't paying attention to what you are doing, this can be pretty exciting.

Sanding the sides

Completing the sides

Once the sides are done it's time to cut the faces.  This is done on the sander as well.  This is the point where it is essential that you understand how crystals form.  When cutting the sides, the blank was held flat against the sanding belt.  When cutting the faces the blanks are held at angles to the belt.

During the shaping step it saves time if you cut the sides and faces of each crystal before moving onto the next.  In other words, don't cut all the sides of all the crystals and then go cut all the faces.  It's faster the other way.  When you get into a rhythm, you can cut a crystal from start to finish in about ten seconds.

Finally, once the faces are cut, then you can put the bottom of the crystal against the belt sander and shorten the crystal to the desired height.  Make sure all your crystals aren't the same height or your geode will look to uniform.

Cutting the faces

Crystal form

Painting and Placing
When working with foam, I like to coat it before I paint it with a mastic.  There are several brands of foam coating material both in and out of the theatre business.  All of them work.  I typically use Childers CP-10 Vi-Cryl because that is what I happen to have in my shop.

After the mastic is dry, the crystals are painted with two different lavenders, one light and one darker as a base coat.

Two lavenders as base coats

Once the crystals are dry, they can be placed.  We placed them with Loctite PL 300 Foamboard Adhesive.  When using adhesives, always use according to the manufacture's instructions, especially as far as safety is concerned.

When the crystals are set and the adhesive is cured, the amethyst color is achieved by washes of Rosco Supersaturated Purple.  Repeat this step until the desired depth is reached.  A gloss coat in-between washes gives greater depth.

Since The Tempest is a magical show, we also added a little glitter spray gloss craft paint at the end.

In context