sealing weathering powders

Other then using dull cote which you can lose some of the effect, i have used hairspray which worked about the same but with a semi gloss effect. i have seen these used on other web sites do they work good? or any other ideas?

http://www.hobbylobby.com/Art-Supplies/Drawing-Illustration/Sharpeners-Tools/Winsor-Newton-Artists-Workable-Fixative-Spray/p/6875

or

http://www.hobbylobby.com/Art-Supplies/Drawing-Illustration/Sharpeners-Tools/Prismacolor-Tuffilm-Final-Matte-Fixative/p/9972

I start my weathering with a light coat of Dullcote. This gives the surface some “tooth”, allowing me to build up a heavier weathered effect. Then the toning down with the final coat of Dullcote gives me just the effect I wanted.

I have some freight cars i want to try weathering on, going to get a can of dull cote as i need it anyway, and one of the fixative sprays and try both and see how they work for me. Will not be getting them till friday at least. Will post pics etc on how it works.