Have large windows with old sash weight pockets.The pockets are 8 ft tall x5"x 6". Want to fill with spray cell foam. Saw Tom fill the window weight pockets on a This Old House Show. I think it was the Boston house project. The foam company I contacted (Touch,n Seal) does not have a slow raise foam (open or closed cell type). After the old pockets are sealed ,the new replacement windows will be installed.Need to find supplier or name of type of foam used. This building is 125 years old and we have many windows, I don't want to use small spray foam cans.