Setting the coloration of an gray fabric at 10, and the coloration of a completely desized fabric at 0, the coloration degrees in between are expressed. Note here that the coloration of 1.0 or more is simply reported as "1.0 or more". To judge the coloration, a fabric is once soaked in water and then squeezed using a mangle (set at approximately 0.5 div.), and then a drop of the iodine solution or the boric iodine solution is applied onto the fabric.
*The coloration of the iodine solution is influenced by surfactants. Attentions are required especially for cationic surfactants, because the blue coloration sometimes does not occur even in the presence of starch, hindered by the cationic surfactants.
*Basically, the coloration should be observed within one minute. Even when surfaces of fabrics are desized, size often remains inside the fabrics with insufficient scouring. In this case, the color resulting from the iodine-starch reaction may become deepened as the time passes. If this happens, another judgment should be performed after 3 minutes.
How to Prepare Reagents
- A] N/50 iodine solution
Dissolve 15g of KI into as little distilled water as possible. Dissolve 2.7g of I2 into it. After dissolving, fill it up to make the total amount 1L.
- B] N/50 boric iodine solution
I2 + 3% boric acid
Dissolve I2 into a small amount of KI solution in the same manner as above. Aside from this, add 30g of H3BO3 to approximately 900cc of distilled water, and heat (at 50 to 60°C) and dissolve it. After cool down the H3BO3 solution sufficiently, mix these two solutions, and fill it up to make the total amount 1L.
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