Hair-do of the week - Married woman, 1435
Married women of the late medieval ages (and early Renaissance) was not supposed to show their hair in any way but cover it all up. This was to show that they were decent women, that they had no interest in tempting men and were good Christians.
(That unmarried women could go with their hair uncovered was not because it would be alright for them to try to tempt men. Unmarried women were regarded as virgins - and in an ideal world they were, though not always in reality - and as virgins their sexuality had not yet awoken and they were therefor much less dangerous. Married women on the other hand, who obviously were not virgins - except in some really rare cases - knew how to tempt and seduce since their sexuality was awoken.)
This portrait shows a woman of a clearly married state, this is shown not only bu the veil but also by the really obvious sign of a wedding-ring on her hand. Women did not have to be quite so wrapped up like this one to be considered decent, but it was not uncommon either. As in most aspects of dressing of both the female and male body it had become a fashion how to do the veils. The veil itself was just meant in the beginning to be a piece of fabric to cover the hair, but it developed into something more, as a way to show how artistically you could arrange your attire, how good you were at folding and forming.
A popular feature at the time was to make the veil stand out a bit to the side at the forehead, which made the face looking more like a triangle turned upside-down. This was achieved by for example by having a hairnet in the appropriate shape, which is a common sight on pictures from this time. But in this example it looks more like the lady has achieved it trough folding the veil in many layers.
And note the pins that keeps the whole arrangement in place.