Is wudu valid when one has applied harqus?
Question

Is wudu valid with hurqus [a black gall ink used in ways similar to henna in the Maghreb region ]?
Praise be to Allah.According to our research, harqus is a substance made from incense and other things [such as oak galls] that are mixed and are used to make patterns for adornment, like henna. What appears to be the case is that when it is washed off, no substance of it is left behind; rather it leaves the colour, like henna, and this does not affect wudu. But if any of its substance remains, then wudu is not valid until that substance is removed, because one of the conditions of wudu being valid is that anything that prevents the water from reaching the skin must be removed.
Please see the answers to questions no. 88179 and 39493.
However, it should be pointed out that if the harqus has substance, applying it does not invalidate wudu, as mentioned is the question; rather it prevents wudu from being valid. In other words, it is not valid to do wudu until after removing it. If it has no substance, then it does not affect anything.
If a woman does wudu then applies harqus to her hand, it does not invalidate her wudu.
And Allah knows best.