There are a lot of disadvantages in using aniline dyes. In comparison to the plant dyed yarns, the aniline dyed yarns are not sun- or washproof. The wool also tends to be stiffer and dryer, because the fat in the wool disappears and a result of this is making the woolfibre break when it's disposed to weigh.
A simple tip to see if aniline dyes are used in a carpet is to fold the pile. If all the pile has the same colour it is most likely to be natural dyed yarn. But, if there is a great difference in the colour where the top is much lighter than the bottom of the pile, there's a risk that aniline dyes have been used in the manufacturing process.
However, aniline dyes are not used in new carpets and the aniline dyed carpets on the market today are most likely already bleached so the risk of being affected is very small.
Aniline, C6H5NH2, also called phenylamine, in a pure condition, a colourless fluid produced by reduction of nitrobenzene. The aniline dyes are furthermore an element of tar-colour consisting of organic, synthetic elements. These are extracted from aniline, toluidines or aniline oils, which are extracted from pitcoal tar.