Not all. Manufacturers supply light fast ratings on their pigments. So watercolour artists are keenly aware of, and look for this.
Commonly, by memory, yellows are not so light fast. And others as well.
If for example, you look up a Schminke (brand) of watercolours, you’ll see their ratings.
There are galleries, many of them, that hide their watercolours away in the dark of storage. Which is a cultural crime. As long as the artist used professional grade paint, that is light fast.
This is a whole, contentious topic. And part of why you’ll rarely see the masters of watercolour in a gallery.
Not all. Manufacturers supply light fast ratings on their pigments. So watercolour artists are keenly aware of, and look for this.
Commonly, by memory, yellows are not so light fast. And others as well.
If for example, you look up a Schminke (brand) of watercolours, you’ll see their ratings.
There are galleries, many of them, that hide their watercolours away in the dark of storage. Which is a cultural crime. As long as the artist used professional grade paint, that is light fast.
This is a whole, contentious topic. And part of why you’ll rarely see the masters of watercolour in a gallery.