Ammonium oxalate

Add about 45mL of 30% aqueous ammonia to a warm solution of 50g of oxalic acid in 400mL of water.  Add sufficient ammonium bicarbonate, ammonia or ammonium carbonate to render the solution neutral by pH paper.  Heat to fully dissolve then filter into a clean 1L Erlenmeyer flask while hot.  Allow to cool overnight, then filter and air dry the resulting colourless crystals (~30g).  The mother liquor can be allowed to concentrate to generate another crops of crystals.

Crystal violet working stock solution

1.  Dissolve 2.0g of crystal violet into 20mL of 95% ethanol.

2.  Dissolve 0.8g of the above prepared ammonium oxalate into 80mL dionised water.

3.  Mix the two solutions together and allow them to stand for several hours at room temperature, before filtering prior to use.  This solution can be stored at rt.

Gram's iodine

1.  Dissolve 1g of iodine and 1.8g of sodium iodide by grinding in a mortar with a little water. 

2.  Make up to 300mL with dionised water. 

3.  Store in a brown bottle at room temperature.

Decolourising solution

Combine an equal volume of acetone and absolute ethanol (or 'methylated' spirit) before the addition of 2.5% v/v water.

Safrinin-O solution

1.  Dissolve 2.0 g safranin-O into 100mL 95% ethanol and filter.

2.  Add 10ml of this safranin solution to 90mL of dionised water.

3.  Store at room temperature.