alumcrystalsilk.md



ALUM CRYSTALS ON SILK

##GENERAL INFORMATION
Alum crystals - that have triangular facets - grown on a silk substrate. The technique used here is called precipitation from a solution. Alum crystals are clear and faceted with great definition so they are often compared to diamonds. However these can get so big that it is not really credible that they are diamonds, but they play with light in similar ways.
Physical form
Surface treatment
Color without additives: transparent and translucent white. (Turns opaque after baking in the oven for 10 minutes at 100 degrees Celcius.)
Fabrication time
Preparation time: 1 Hour
Processing time: 1 day or overnight
Need attention: None. Leave in a warm place, don't move or touch it.
Final form achieved after: 1 day
Estimated cost (consumables)
2,00 Euros for a 400 ml saturated solution
##RECIPE
###Ingredients


Alum powder (also: potassium aluminium sulfate, potash alum, or  - 125 g (plus some more just in case)

we will try to reorganize these molecules into crystals.


Water - 400 ml/gr

To dissolve the alum powder and reorganize into a crystal


Water - 1000 ml/g

to create a bain marie


Silk - a 10x10cm swatch

As a substrate for the alum crystals to attach to


###Tools

Cooker or kettle
A piece of silk

A smooth glass jar or bowl big enough to fit your piece of silk without touching the sides or having to fold or crease it. Make sure this it totally clean.

A wide heat-resistant bowl or oven pan this is the bain marie: the glass jar should fit inside this bowl and have some space for hot water
Spoon

A stick or chopsticks that are long enough to stay put on top of the glass jar.

Clips to fasten the silk to the stick

###Yield
About 80-100% of the alum powder will attach itself the silk in the form of larger crystals.
###Method


Preparation

Weigh the alum
Prepare the silk by attaching it to the wooden stick with clips. When you hang it inside the glass jar it should not touch the bottom or the walls of the jar
Boil the water
Put the glass jar inside the wide oven dish/pan. Pour as much boiling water as possible into the bigger pot, without making the glass jar float. This is the bain marie that will keep your crystal solution warm and help it cool down very very slowly (resulting in bigger crystals).
Put this in a (warm) place where you can leave it for 8-16 hours without anyone moving or touching it.


Dissolving the alum

Measure 400 ml and put it in the glass jar (which is already inside the bain marie to keep it warm).
Spoon by spoon, add the alum while stirring. When no more alum dissolves and just sinks to the bottom, your solution is saturated. If there are grains on the bottom, pour off the liquid and clean the jar before continuing. You don't want anything on the bottom of the jar.
Now suspend your silk into the jar, again making sure it doesn't touch any sides or the bottom, and not folded in on itself.


Let the crystals form

Now leave the crystal to grow. The less you touch it, the easier it is for the molecules to find each other on the silk and form big beautiful crystals.
If you have the patience, give it 16 hours. But pretty decent-sized crystals will have formed as soon as 6-8 hours later.
Rinse them under cold tap water and let them dry.


###Drying/curing/growth process

Mold depth:  				 N/A
Shrinkage thickness:      N/A
Shrinkage width/length:   N/A

Shrinkage and deformation control
N/A
Curing agents and release agents
None.
Minimum wait time before releasing
6 hours
Post-processing
Store the crystals in a dry place. They will re-dissolve immediately when the are submerged in hot water, starts to dissolve after an hour in water at room temperature, and is completely dissolved after being in water at room temperature for 4 hours.
Don't throw away left-over liquid or unused crystals, they can be redissolved a next time.
Further research needed on drying/curing/growth?
More research on colorants could be done. Black soot ink results in black crystals, purple crystals can be achieved by adding some chromium alum powder (or: potassium chromium sulfate dodecahydrate) to the solution.
###Process pictures
Silk inside the bain marie, Loes Bogers, 2020
Improvised suspension system, Loes Bogers, 2020
2-3 cm crystals on silk, Loes Bogers, 2020
2-3 cm crystals on silk, Loes Bogers, 2020
Alum crystal on an LED (top) turned opaque white after 10 mins in the oven at 100 degrees celcius. On the bottom: a borax crystal (recipe here), Loes Bogers, 2020
###Variations

Add a colorant such as black soot ink (other natural dyes are still experimental!)
Turn your crystals opaque white by putting them in the oven for 10 minutes at 100 degrees celcius.
Use different textiles (e.g. velvet attracts many small crystals)
Lay your silk flat in a bowl to cover the entire surface with smaller crystals
Let the crystals grow without the bain marie to see what happens
Glue a piece of silk on an LED with hot glue to grow a crystal that you can use in electronics projecs instead of plastic casings (see video below).
The same technique can be used with epsom salt, sugar and borax.
Adding conductive paint to the solution creates crystals that can be used as capacitive sensors.

##ORIGINS & REFERENCES
Cultural origins of this recipe
Potassium alum was known to the Ancient Egyptians as early as 1500 B.C and was described in the age old writings of Pliny and Dioscorides under many different names: alumen, salsugoterrae, stupteria and other substances with vaguely similar properties and uses like: misy, sory, chalcanthum, atramentum sutorium, iron sulfate or "green vitriol". The word "alum" is still used for many different kinds of alum compounds and are often used interchangeably but they are not all the same. Potassium alum is mentioned in the Ayurveda with the name phitkari or saurashtri.[citation needed] It is used in traditional Chinese medicine with the name mingfan (明矾).
Potassium alum was used extensively in the wool industry from Classical antiquity, during the Middle Ages, and well into 19th century as a mordant or dye fixative. The textile dyeing industry in Bruge, and many other locations in Italy, and later in England, required alum to stabilize the dyes onto the fabric (make the dyes "fast") and also to brighten the colors. As an ingredient it was of utmost economic importance during the Renaissance.
Needs further research?  Yes
###Key Sources
This is a variation on: Alum Crystals in "Textile as Scaffold" by Anastasia Pistofidou for Fabricademy 30 October 2019. Lecture notes: link