I have made a couple of postings about weathering my T-55/ Tiran 4/5 just like the tank in the movie "The Beast".
I saw an article that Mig wrote in missing-lynx.com article section. He talks about how to apply the pastels to your vehicle and adhere them with a little bit of terpentine. Now he does not state in the article that he uses any clearcoat or a dullcoat to seal the weathering, but he does state that if you use a clearcoat on your vehicle then weather it with pastels/powders that the weathering will not adhere.
My question to you is this, I will be useing, brushing it on, Johnsons future acrylic floor wax as a clearcoat base to laydown my decals. Will the heavy weathering of the pastels/powders to the vehicle adhere has well as if I did not use the clearcoat?
Also I am going to do a pin wash as well, should I do the wash first and then the heavy weathering of pastels/powders?
What should I do?

The way I understand MiG, He apints, he dry transfers/paints markings, then he pin washes and finally adds pigments. Then overcoats as needed. The Future overcoat will still keep pigments from adheering as well, although if you use a good dull flat coat and then pigment, it may work better that way.

Hope someone else can chime in here...

After painting with clear coat and applying decal make sure to spray matt coat before using pastel. pastel/powders work well on matt finish.

i have been doing alot with powders and they wont stick well without a dullcote. the best way is to spry a dullcote then apply powders the u can apply another dull over it to seal it in. i have done it this way many times and it works great. i have used any washes with paints since using powders. mig and cck are the best. u will love them.

I find the best mixture to get pigment powders to stick is to mix the pigment with thinner and add a little acrylic paint into the mixture. So if you are doing a snow type weathering, you mix it with matt white.

I mixed mine with desert yellow and i can assure you the powder sticks hard. If in the event you cant get it to stick still with this mixture, PVA glue would be the final nail in the coffin.