High grade Calcium hydroxide (Calx) alkaline (base) often used in eco-friendly and organic indigo vat dyeing, particularly when using the vat 1-2-3 method.
 
Supplied in a pack of 100g.  This is the ideal amount for combining with 200g fructose and 50g of indigo dye powder when following the 1-2-3 method.
 
Calcium hydroxide acts to ensure the pH in the dye vat is alkaline, conditions which are necessary for indigotin to be released from indigo.  
 
Calcium hydroxide can easily be disposed of by vigorously stirring the dye vat, such that it combines with carbon dioxide forming calcium carbonate (chalk) which can be safely disposed on down domestic drainage or in composting.