Digital BW, The Print

I'm experimenting with prismacolored pencils and pastels on Moab Entrada Natural 300.  
The paper takes the colors very well and I'm guessing I should spray them once I'm done.

There's Print Guard, PremierArt PrintShield, and Bulldog.  Can anyone recommend a spray 
that will do the job and not detrimentally affect the way my handcolored prints will look?

Gracias