A Different Kind of Π Pendant

I got the design idea for this pendant from a slightly different kind of Pi..

π = iMRT is the formula for osmotic pressure.

While the formula for Osmotic pressure gets complicated (depending on the specific properties of the solute/solvent and the temperature), I think the visualization puts the general principle across.

This is a polymer clay craft (I use Fimo brand), and I plan on making many more variations of this..

• Polymer clay (I always use Fimo) - At least 3 different colors. I used:
• For the 'solvent' - White and Magenta (which I mixed from leftovers)
• For the inner part - Blue (similar to what I would call Turkish Blue shade that I mixed from leftovers). This color should be a nice contrast to the 'solvent' colors.
• Glass Christmas ornament - For creating the convex shape
• Sharp blades
• rolling pin for clay
• modelling tools or metal knitting needle - for smaller details.
• A pasta machine - mine goes from 1-thickest to 9 -thinnest (but I never use thinner than 6 because the machine ruins it).
• Oven that can bake at 110C/230F.
• Extremely fine wet sanding paper - I used 1500 and 2000.
• Cookie cutters - circle for the main shape, rectangle for making a cutout.
• Fimo liquid
• Metal wire and small bottle nose pliers - for making the hanger pin.

Optionals and alternatives :

• Latex gloves - they minimize fingerprints which makes sanding easier.
• Lightbulb - instead of a glass Christmas ornament.
• Gel type superglue - instead of Fimo liquid.
• Jewellery findings - head pin or screw eye pin.

Prepare the colors

1. I started by conditioning equal amounts of White and Magenta. (each 3x5cm rectangles 0.5cm thick).
2. Cut each rectangle into triangle and stack them.
3. I decided my triangles were too long so I squished them a bit before connecting them.
4. Roll the connected triangles a little with a rolling pin - so they are a good thickness for the machine.
5. The piece should always go into the machine with both colors ( either of the green arrows )! Don't put them through from the wrong direction (red arrows) otherwise you will get a single color at the end.
6. I left a little bit of white and magenta on each end so that I would get a blend from full white to full magenta.

Put through the machine

1. Start on the thickest setting and then reduce by about 2 settings (mine goes from 1 to 3), folding in half each time.
2. Keep doing that until you happy with the blend.
3. You will notice that the piece widens as it goes through... just try to keep it straight and even when folding
4. finish of by creating an even-ish rectangle
5. cut it into 4 even strips that go from Magenta to White and stack them.

1. Run the stacked strips through setting 1 on the pasta machine - starting from the light color (white) to the darker (magenta).
2. Keep reducing the thickness while rolling from light to dark... my poor machine only goes to setting 5.
3. Starting from the white tightly roll-up the long ribbon.
4. At the end you will always have some unevenness at the edges.
5. I press the roll a little to make it tighter, and then press the sides to make the diameter of the circle a little bit wider.

Slicing the roll

• My final roll was 3cm in diameter. Using a sharp blade slice of 1-2mm slices.

To prevent the roll from distorting too much when you slice roll it by 90deg between slices.

• To create larger thinner circles I ran each slice through the pasta machine 4 times- each time turning it while reducing the thickness.
• Each of the slices is then smoothed, with the palm of my hand onto the Christmas ornament.

Gloves have appeared so that I don't leave pesky fingerprints on the shapes (its better if the gloves are a little tighter than mine..)

Creating the final shape

• Using a circle cookie cutter, I trim each slice while already on the ball. (keep these leftovers - you can use them later to connect the 2 sides)
• I started by gently marking out where my cutout should be.. making sure that it is about even on each of the 2 circles. Then I cut it out with a rectangle shaped cookie cutter (keep the leftovers- you can use them later for the finish).

Bake Nr. 1

• Preheat the oven to 110C (for Fimo - other clays have slightly different temperatures)
• Place the ornament on a baking sheet and tent with aluminum foil.
• Bake for 30 min.

1. Once the pieces have cooled remove them from the ornament with a plastic or wooden pick (the thick needle won’t work if the piece is adhered to the ball, and sharp metal can cut or scratch the clay).
2. The unsanded pieces have some rough edges, rough surface, and alot of 'dirt' (smudges of darker color on the white and general dust)
3. Trim the rough edges are with a sharp blade.
4. Because I used gloves I started sanding with an extra fine grain sand paper immediately -

• For wet sanding use a bowl of water - I dab water on the piece with my finger and then sand in small circular motions. (I didn't bother with the interior because the shape will be closed).
• Every once in a while I wipe the piece off with clean water (into the bowl) and clean off the sand paper in the bowl as well.
• For the second sand paper (my 2000 grain) I wrapped the ornament in aluminum foil, and placed the pieces back onto the ornament for sanding - that way I can apply a little more pressure.

(For now you should keep the water, but at the end- don’t pour the water directly into the drain. To get rid of the water pour it through a very fine sieve (or cloth) before pouring it out so the 'dust' can go into the trash and not the drain.)

The final piece is smoother - but I still couldn't get rid of that 1 pesky piece of glitter

Connect the sides

1. Roll out a thin piece of Magenta (from your trimming leftovers).
2. With or without liquid Fimo (I prefer without when possible*) line the inner part of 1 side.
3. Add the other side and press them together gently - you want some of the Fimo to stick out.
4. With a finger or a metal knitting needle slowly smooth out the seam between the two sides.
5. For stability I placed the piece on the rectanglular cookie cutter that I used to make the cutout.

Bake Nr. 2

same as before - preheat, still standing on the cookie cutter tent w. foil and bake for 30min.

Sand Nr. 2

same as before - wet sand the edges.

(* the reason I prefer to not use liquid Fimo on some projects is that it can add some 'shine' after its baked.. or show the horrible finger prints you accidentally left. This pendant is meant to remain matt so no shine is better)

First build a base -

• Roll out the blue (contrast color) on the thickest setting on the pasta machine.
• Using the rectangle cookie cutter, cut out a piece.
• Fit the piece on the bottom of the U cutout and press gently (you can use liquid Fimo here as well)
• Trim the over hang on each side with a sharp blade.

Bake Nr. 3

same as before....

1. Cut a piece of metal wire (about 4 cm).
2. Using the bottle nose pliers make a loop on each end by grabbing the wire tip and wrapping out and around the pliers.

1 loop will have the leather cord or necklace go through it (the prettier one), the other will be baked into the Fimo for stability.

Adding the pin-

Now you have a surface you can press down on when connecting the metal pin.

Since my planning ahead was marvelous I did not make enough of the blue that I wanted visible. So, to fasten the pin I used a darker shade of blue, which I later covered on the outside with the color I wanted.

• Wrap the part of the wire that will be embedded with clay.
• Press the clay wrapped side into the base - make sure the wire is straight and the eye is facing the right direction.
• Add the ‘correct’ clay on both sides to fill in the shape of the cutout and completely cover the darker clay. It should stick out a little from the surface of the main piece.
• Trim the blue so that it is flat with the main piece.
• Cut thin slices from the blue to wrap over the wire covering it up until the eye.
• Using the thin metal needle flatten the top of the blue to create a sharp edge, and smooth over the covering of the wire.

Bake Nr. 4

Same as before

Sand Nr. 3

• Sand the blue clay as flat as possible with the Magenta/White.
• Sharpen the edges and smooth the blue that covers the wire.

Now that the whole piece is sanded you can add the last touches-

From the leftovers of the cutout take the lighter white edges and roll them into a very thin 'snake'.

Make tiny balls..

For each ball -

• put a dot of liquid Fimo with the tip of the needle
• pick up a ball, with a clean needle, and place it on the same spot.
• press very lightly

When you have enough on...

Bake Nr. 5

The design idea for this pendant came from the 'glassware version' of demonstrating osmotic pressure - in case that wasn't already obvious...

Some fun but unrelated ideas:

• You can make your own semipermeable membrane at home-
• cut the core out of a potato. The potato cells will act a membrane that will only let liquids pass.
• An egg shell is a semipermeable membrane - it is clearer to see how it works if you first 'melt the calcium off' in vinegar.
• You can play with the concentrations of solutions on the different sides of the membrane by adding different amounts of sugar (or salt) to water.