Abstract: A paint spray booth is provided containing a plenum packed with a contact material for treatment of paint overspray generated during operation of the paint spray booth. The contact material is packed to provide a relatively large surface area and a relatively large interstitial area defined by the contact material. As paint overspray and bulk fluid is drained and channeled through the plenum, contact efficiency between the bulk fluid and the overspray is maximized. Paint overspray is thereby effectively detackified.