Is there an ideal separating medium for lift-slab construction?
The medium should preferably be chosen on the basis of the type of job and the program of construction. Most fluid-type separators consist of either a resin or wax dissolved in a volatile spirit, which evaporates on application to leave a thin hard film on the surface. Physical media (sheets of building paper or polyethylene) have the advantage that as soon as they are laid on the slab, a work crew can begin placing reinforcement for the next slab. The disadvantage of sheeting is that it tends to cause corrugations in the soffit of the slab. While the proprietary compounds vary widely in drying time, chemical composition and the like, it is fairly easy to formulate a number of requirements for the basis on which they can be evaluated for a particular job. Briefly the medium should be satisfactory for: bond prevention; drying time; resistance to abrasion and wear by work crews; site weather resistance; ease of removal after lifting (preferably it should oxidize on exposure to the atmosphere); non-interference with subsequent floor or ceiling finishes; economy; ease of application; non-staining (at least not permanently); early and easy color fading; and chemical inertness.