I've been experimenting with Future to achieve the look of chipped and peeling paint much the same as many do with the hairspray technique. Once I put down rusty base color (in the instance below, PolyScale rust mixed with RR tie brown, 50/50) I lightly spray with Future Floor Finish. When dry I then lay down a few light coats of my finish color (Floquil UP Armor yellow here). Again wait to dry for about an hour, and begin to work the model with a stiff brush and Windex. For some of the inside corner areas, I chewed the end of a toothpick a little to do the scrubbing. Some acrylic washes of raw umber and then dry chalks finished this piece.
You might recognize the chain drive Mack FCSW that I introduced you to by Joe Enriquez some time ago. Please don't expect the kind of detail modeling Joe had accomplished on his water truck but I'm only trying to show this paint technique here.
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Excellent technique. And it seems relatively straightforward. Thank you for posting. -- Russ