For Watercolors, Goache, and Ink
"I use Krylon workable fixative and then go over it with Golden UVL watersouluable varnish mixed to package instructions."
"The spray fixative made by Krylon is the one that can be used for several different mediums such as pastel, pencil and watercolor. I use that brand but I am sure that there are several others out there that will do the same job. I use the workable fixative because it allows me to go back in and make changes as required. As for the Varnish it is made by Golden is UVL and water based. Package instructions state that it can be mixed in a 2-part varnish and 1 part water mix. I use a 2-inch paintbrush (good quality) obtained from the local hardware store. The first coat I give a very light quick brushing going over an area only once. This insures that the watercolor paint will be set in place and will not move in subsequent coats. It takes about 10 min for the first coat to cloud over and dry. I then apply a second more liberal coat and leave the painting to dry."
"I spray both sides of the painting with the fixative before I glue it to a piece of mat board. The reason I do that is to insure the integrity of the painting. As for the glue I use either Gel Medium from Golden or White carpenters glue (it's Acid Free). Put the glue on the mat board spread it with a putty knife and then place the painting on the glue, push out the bubbles if any, and then cover with a sheet of glass and lots of weith to hold if flat while the glue dries."Source