Sealant Technologies recommends using open cell spray foam in 5 gal buckets because they are easy to transport, manage and dispose of. The open cell spray foam can be designed specifically to integrate into the portable spray foam machine. Open Cell spray foam would be a good choice where larger framing sizes need the greatest R-value per inch possible. Also, because this is a no heat spray foam, it's possible to get into and out the project quickly and without a lot of down time.
Open-cell spray foam in 5 gallon pails has an open cell structure where the cells are filled with air. The open-cell structure renders soft, flexible foam, with a density of about 0.5-0.8 pounds per cubic foot (pcf). Still air is the primary insulation medium in spray insulation, fiberglass and cellulose. These insulations work by reducing the natural air movement within these materials thereby reducing the ability of the material to conduct heat. The R-value per inch of spray insulation typically ranges from R3.6 to R4.5 per inch.