Rapid Prototyping involved creating a working model of various parts of the system at a very early stage, after a relatively short investigation. The method used in building it is usually quite informal, the most important factor being the speed with which the model is provided.
There are water-and solvent-based -- also called oil-based -- polyurethane varnishes. Water-based polyurethanes are more environmentally friendly and safer to use than solvent-based, but they are not as resistant to wear and tear as solvent-based products.
Equipment Storage Fluid. Environmentally Sensible Solvent based Polyurethane Foam & Resin Cleaners formulated with organic solvents, wetting agents and a corrosion inhibitor. They are biodegradable, non-toxic, non-corrosive, residue free, Low VOC, non-flammable, no ODCs, non-HAPs and No SARA Title 313 Reporting.