I've had concerns with foam in walls with only 2-3" and the resulting air space & convective currents. spray foam for walls is not one of my recommendations to my clients. instead foam sheathing to exterior of walls caulked,taped & sealed. conventional insulation & air tight drywall approach. a better and affordable wall with no extremely long payback like spray foam in walls.  Insulation Spray Coating
Charles spoke of a "huge problem" of convection within cavities not filled with foam. This is a false assertion. The trillions of trapped air cells in foam insulation prevent heat transfer at a rate that would cause those problems. Also the wood framing members are relatively good insulators themselves unless the wood is particularly dense. Convection currents against foam insulation are not the problem he asserts. He also said" the homeowner is literally pissing money away if he pays for this spray foam job - or any job like it - for he will only be gaining a marginal amount of insulation effectiveness." This is a ludicrous statement. The structure pictured above will have a very effective performance despite his assertions. My only concern is humidity. Closed cell foam does not permit moisture migration and trapped moisture could be a problem, especially if the AC is not running due to moderate to cold temperatures.
Warm spraying is a novel modification of high velocity oxy-fuel spraying, in which the temperature of combustion gas is lowered by mixing nitrogen with the combustion gas, thus bringing the process closer to the cold spraying. The resulting gas contains much water vapor, unreacted hydrocarbons and oxygen, and thus is dirtier than the cold spraying. However, the coating efficiency is higher. On the other hand, lower temperatures of warm spraying reduce melting and chemical reactions of the feed powder, as compared to HVOF. These advantages are especially important for such coating materials as Ti, plastics, and metallic glasses, which rapidly oxidize or deteriorate at high temperatures.[1] Spray Coating
Plasmas affect materials at an atomic level. Techniques like X-ray photoelectron spectroscopy and scanning electron microscopy are used for surface analysis to identify the processes required and to judge their effects. As a simple indication of surface energy, and hence adhesion or wettability, often a water droplet contact angle test is used. The lower the contact angle, the higher the surface energy and more hydrophilic the material is.
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Appropriate training for personnel who are responsible for conducting the painting procedures is important, which may be from a professional training provider or the product supplier. There are also hazards related to the disposal of wastes and materials that are contaminated with potentially harmful chemicals. Decontamination procedures and Material Safety Data Sheets for various products are important. Safety is improved through: Spray Coating