Just to make it clear, DO NOT SCOTCH GUARD A COMPLETED LAMPSHADE. I was restoring the entire cover and liner for this lampshade. When restoring an entire sewn shade, the cover is the first application and there is no other fabric on the frame of the shade.
The decor of this home is transitioning from a formal to a contemporary look, Originally this brass hanging light had a silk shade and owned by a very fine lady. The home changed hands and is now occupied by bachelors.
Silk Lampshade Cleaned with a Lint Roller
For a more masculine look, I used an ivory linen fabric for the new cover and trimmed the shade with black soutache trim. The restored shade looks nice on the brass hanging lamp and is not so formal.
Lampshade Restored with Linen
In an attempt to make the new linen cover more resilient to absorbing dust and easy to keep clean, I treated the linen cover with scotch guard. This is the first time I have tried treating a lampshade cover. It worked very well.
I would not treat a manufactured shade. You just cannot be sure of the fabric content or process used for making the shade.