FYI ~ That “pebbly” dry surface you mentioned will really allow pigments to adhere in an almost permanent manor requiring no other fixative “top coat.” I use the pigments for both weathering and color shifting.
I attempt to champion this dry spray+pigments technique where ever and when ever possible on this site.
(Just one man’s experience.)
p.s. I have not experienced the “rubbing-off affect” mentioned earlier but then I don’t pick up my models like I would a Coke bottle. I usually use the “double fork lift” technique using fingers under the front and rear ends. Both the dry spray and the pigments seem to take more than a bit of burnishing to disturb and are not affected by just the occasional touch.
Vehicles seen below all weathered with oil pastel pigments over a very dry matte clear coat with no further top coat or fixatives.
Base coat is Model Masters #1911. Decals are applied using the wet Future technique*. Then all is top coated with an application of Tamiya TS-80 Matter Clear applied extremely dry.
I literally then scrub the pigments into the tooth of the dry matte clear coat with a small stiff bristle brush,
M3 in PTO markings: Battle for Kwajalein Atoll
M8 in ETO markings.
All lettering comes from Star Decals.
*Link: