Assalaamu alaykum. I have a question about dirt when performing Ghusl (ritual shower). If a person sweats from being out in the sun or from running, then, normally, this sweat will dry and turn into dirt on the skin. If a person performs an obligatory Ghusl after this sweat dries on the body, is the dirt considered a barrier to the water when performing Ghusl? I have concerns about this because my back sweats from being in the sun, and when I take a shower, I am not able to scrub all of my back, except with some difficulty. It usually takes me a while. That being said, are the areas which I cannot easily scrub considered to have barriers to the water because of the sweat? May Allah reward you.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

The scholars of Fiqh stated that this dirt caused by the accumulation of sweat is not an obstacle that prevents water from reaching the skin.

Al-Isnawi said, "It is conceivable that ablution and Ghusl are valid while a person has something attached to his body that prevents water from reaching it which he can remove, and he is not obliged to repeat the prayer. This is in regard to the dirt that originated from one’s body, which is the sweat that accumulates on it; it does not harm, contrary to the dirt that is due to dust, as mentioned by Al-Baghawi in his Fataawa, and it is a considerable view."

Allah knows best.