There exist substances which reduce the ability of the item sprayed to carry a charge. These can be sprayed on, or applied to clothes as a sheet added to the dryer. This is useful to decrease the avidity of clothes for lint and pet hair.
I propose that a spray be devised to do the opposite. Sprayed objects will more readily take on a static charge and then adhere to other objects in the environment.
This would be useful for the circumstance where you desire more cat hair (surreptitiously released from a paper bag for the purpose) to adhere to a person's clothes. Sprayed hair will more readily stand on end for that VanDeGraff hairstyle. Could one spray one's own self and then accumulate an increased electrical charge by scuffling across the carpet? This might be determined experimentally by doing so and then gently touching the ear of a person preoccupied with removing cat hair from his trousers. A series of trials with and without spray will of course be necessary to be sure of the result.
But chiefly one could use this spray to facilitate the making of glueless, messless, nondestructive collages, art bulletin boards or the like, adhering small treated items (such as plastic googly eyes) to a static board (which might be a poster advertising an important public health message).
Persons dismayed by the art (or hair) can simply pluck off any adherent offending objects, throwing them on the ground and stomping on them as their own conscience moves them to do. No damage is done and everyone can stay friends.-- bungston, Feb 21 2017 Inspiration! Dirty_20display [bungston, Feb 21 2017] I saw a nifty thing where they used electrostatics to attract paint to objects. They use it on cars. Your applications differ because the objects are nonconductive. Possibly electret polymer microparticles could do what you suggest.
wikipedia says "Electrostatic coating is a manufacturing process that employs charged particles to more efficiently paint a workpiece. Paint, in the form of either powdered particles or atomized liquid, is initially projected towards a conductive workpiece using normal spraying methods, and is then accelerated toward the work piece by a powerful electrostatic charge."-- beanangel, Feb 21 2017 This could never be free as you'd always have to charge (sorry). The electrostatic coating that Beany mentions requires electrodes to be attached to the spray gun and the object to be painted. They are nifty though - I have seen a spoon bowl facing away from the sprayer still be coated (although thinner than the facing side).-- AusCan531, Feb 22 2017 New! From the makers of Gravity-away and Mag-sol comes: Electrons-in-a-Can! Instantly charge any non-conductive surface at the touch of a button. Pairs of surfaces that were previously cohesive are now effortlessly rendered mutually repulsive! Plus, it's perfect for that "just stuck a fork in a toaster" look.
The secret is in Electrons-in-a-Can's patented dual-ingredient formula: the first ingredient penetrates deep into the target material, searching for and neutralizing any latent positive charges. The second component coats the target surface creating a uniform negative layer.
* We are not responsible for any damage to electronic components or for any adolescent pranks that may result from improper use of Electrons-in-a-Can.-- Cuit_au_Four, Feb 22 2017 random, halfbakery