ABOUT PASTEL DRAWING TECHNIQUE.
All painting colours are made with the same pigments.
The difference is given by the media used to carry on those pigments.
In the case of Pastel, it is used a little bit of kaolin, clay and tragacantum gum; all of them are materials found in Nature.
In Pastel, the pigment is affected the less, keeping the colors to its best intensity and brightness, been the media that ensures the longest permanence of its characteristics through time.
Undoubtely, a well performed Pastel work will be an art piece that will last for generations.
It is not necessary to apply any plastic fixative; unless you desire so; by doing this, the brightness will be affected a minimum but it will make the work more resistant to direct light or humidity exposure.
When framing the work, if you decide to use glass, clarity will be reduced If you placed the portrait protected from dust and direct sunlight it can be framed without glass protection.
Nevertheless, if you want to protect it, the best choice is a material called plexiglass ( Widely used in U.S.A.) preferable "museum quality" which is 100% transparent, 100% non-glare and 100% UV block. This is a plastic material with the advantage of its light weight and non-breakeability.
All Pastel paintings must be handled carefully; avoiding as much as possible any mistreatment to the paper or scratching on the surface.
The person in charge to frame your art piece must be told that it is a Pastel, so he takes the necessary precaution in its handling.
If the handling and framing of the portrait is performed appropiately, you will have the guarantee that the colours will last as you actualy see them for a very long time.