Tuesday, March 18, 2014

WHAT IS ALUM?

Students often ask for clarification on alum.  What is it and what are the different products being sold as alum.  I have always used and sold Alum which is Potassium Aluminum Sulfate and is sometimes just called Aluminum Sulfate.  But in fact there is a product sold as Aluminum Sulfate that does not contain the Potassium.

So what is the difference?  Potassium Aluminum Sulfate is refined in such a way as to remove iron from the final product.  It appears to go through several processes of refinement.  Yet Aluminum Sulfate can be a low iron grade and can thus be used for mordanting. The problem with iron is it will dull and darken the color response on the fiber thus resulting in disappointing color.

Looking through suppliers I find both products.  I've called to verify that a product listed as Aluminum Sulfate is in fact just that.  So the question is what is the difference?  I'm not sure but the next step is to order some, do some mordanting experiments and compare results.

For a further discussion of alum see About Mordants by Michele Wipplinger at Earthues.  This is an excellent article addressing the differences.

In the meantime I am ordering some Aluminum Sulfate to compare with my Potassium Aluminum Sulfate.  Stay tuned.  The dyepots will be simmering.

Sunday, June 23, 2013

INDIGO AND THE ECONOMY OF COLOR

A book came in the mail as part of my ongoing interest in methods of dyeing with Indigo.  The color blue and the magical process that imparts a short lived yellow, then green and finally blue to cloth or fiber is a surprise each time it occurs. It is both fresh and engaging.  But the process has been modified over the years to incorporate modern chemicals for speed and success in making a vat.

Traditionally indigo is a dye that has required patience and time.  It is unlike other natural dye materials in that it doesn't readily dissolve in water.  It must be reduced, a process which removes the oxygen from the dye vat thus making the indigo available to the fiber.  Anything less deposits the color on the fiber but not into the fiber.

Indigo dyeing and its process is found in most cultures around the world.  But recipes vary according to local materials.  

After many attempts to use the modern recipe of indigo, thiox and lye I finally gave up.  Not because it didn't work but because I was getting headaches from the process.  The ProChem MSDS (Material Safety Data Sheet), THIOX, identifies a number of hazards in Section 3 and Section 10 including production of toxic carbon monoxide fumes.

I mentioned this to a friend and production natural dyer in Maine who did large quantities of indigo dyeing.  She set up a carbon monoxide meter to monitor the levels in her dye room at work.  While the alert did not sound it still indicated some carbon monoxide was present.

So what is natural about using thiox along with lye?  Probably not a lot.  It is, however, a quick way to get a vat up and running without a wait time.

But it occurs to me that slow fiber making is a retreat to the methodical sanity of meditation and mindfulness.  Process which is purposeful and unhurried.  And so a new quest began and continues.  To research and develop some natural fermentation vats.  They take longer but how quiet and satisfying it is to dye blue without toxic fumes.  

And so I will continue to document my journey into the the dark world of blue.  Indigo is for me the most magical of dyes.  And a fermentation vat is akin to my cheese making and baking with sourdough.  There is a thread which ties these practices together in a neat bow fed by biological process and bacteria.

 Stay tuned.