Color indicator

Normally, the areas and animals affected by the Color are pretty easy to see, as they take on the Color which oversaturated them. But sometimes, one cannot rely on their eyes, like when the food processing plant approved of a batch of contaminated food or when one wants to use the water from the river that has been affected earlier.
That's why Color indicators have been created.
This little slits of tissue-paper are soaked with substances that, in the presence of Colors, change their hue.

Evolution of indicators

First indicators were sensitive to all of the Colors at once. But more than often, this caused the indicator to come out gray and hard to read. This type is really liked by the travelers and researchers as any hue that departs from the gray means that there is some kind of contamination in the tested sample.
Later, as new technologies developed, new indicators were created. These ones detect only one of the Colors. They are more widely used by the public in everyday life to check the food, water, and even air for contamination. A lot of rulers tend to use them to check for poisoning.
In some places, one or two of these are included with every food that comes out of Ration suppliers. But normally, they are sold in small metal boxes made out of material that blocks out Colors. There are various sets of boxes, some include slits of paper sensitive to only one Color, while others have every type of indicator at once.

Mechanics & Inner Workings

In case of contact with anything that has higher than normal levels of Color, the substance the indicator is soaked in starts to absorb that Color. Because of that, it changes its hue to one contrasting the Color it has absorbed

Item type

Tool

Weight

Box usually weighs around 100g and contains 700 indicators (100 for each of the Colors and another 100 that is universal)

Reminder!
Remember that the color you can see on the indicator is opposite (contrasting) to the one it detects.

Defective ones

Depending on where you are going to buy one of those things, watch out.
In areas controlled by Witches, Color indicators tend to be very bad at detecting Blue.