The seat-a-lator's original intention was to lay over furniture springs and keep cotton batting from being forced through the springs as the furniture was sat on. That was the normal seat construction of its day. Its purpose was to isolate the springs from the next layer above it, and prevent damage to that layer. In a couch or chair, the next layer above is the seat and seat cushions. In a car seat, the next layer above is the seat foam. Now days that type of construction is basically non existent. La-Z-Boy is the only manufacturer I know of who still uses seat-a-lators in their seat construction and their use of it is redundant. They cover their springs with a layer of synthetic fabric and put a seat-a-lator on top of that under their seat foam. (which doesn't work, by the way.)
Somewhere along the line, the seat-a-lator (also called permalator or flexalator, depending on what company manufactured it) was suspended from helical springs as a cheap alternative to actual springs. As time passed, newer synthetic products appeared to replace the seat-a-lator over springs with cotton batting on top of that,with a one piece layer called seat decking. Seat decking comes in many different forms and thicknesses. I will take pictures of some different kinds of seat decking and post them tomorrow.
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Last edited by DanTwoLakes; 10-22-2007 at 10:21 PM.