[anthony]

I suppose you are right. English is not my language.

So for you "irritation" has -among other meanings- the same meaning as "stimulation". Is that correct?

The Dutch/Flemish (my language) word "irritatie" does not have this "stimulation" meaning. When in a Dutch text about pearls the word "irritatie" is used it only has the negative meaning.
So my original question comes probably from a mistake once made in a English-Dutch translation, that all other Dutch authors adopted. And when I was reading English books or for intance the text on this website I also made this mistake thinking that "irritation" is a negative feeling.
Your English text will be OK then and I will continue playing Don Quichote in Holland and Belgium.

Are there contributors to this forum from Germany, France,.., Spanish, Arab countries? Because I have another question now..