Test for desizing efficiency - TEGAWA rating
Desizing Efficiency Test:
Desizing efficiency is found in two ways conventional and TEGEWA method.
In this method we first take the weight of the sized fabric, let it be W1. Then desize the fabric, dry & take the weight, let it be W2. After that the fabric is treated with 3gpl (35%) HCl at 700 C for 30 min. dry & take the weight of the fabric. Let it be W3.
Total size = W1-W3.
Residual size = W2-W3.
Desizing Efficiency = (Total size – Residual size)/Total size X 100.
Reagent: potassium iodide (10 gm. Of KI (100%) in 100 ml water, add 0.6358 gm of iodine (100%) stir and shake; iodine is completely dissolved. Fill up to 800 ml with water then complete to 1000 ml with ethanol. (Shelf life approx 6 months only).
1. Spot drop wise solution onto fabric.
2. Rub in gently.
3. Assess change of color.
Note: the test must be carried on fabric cooled down to room temperature; residual alkalinity has to be neutralities prior to the test.
No change of color = no starch size present.
Pale blue to bluish = presence of starch size or blend
Violet =of starch size with synthetic size
Pale blue to bluish violet = refer to violet scale TEGEWA This indicates residual Starch content.