Here are two projects that demonstrate how I approach the problems of early upholstery on antique furniture. The first example started out as a well-made gentleman's Victorian armchair in the Louis XV rococo revival period, about 1860. Then, sometime after the Civil War, when everything "Turkish" was popular, this sturdy chair was heavily modified by replacing the arms with flat boards, squaring off the crest completely, adding shaped strips on the curved sides to "clean up the lines", and, finally, cutting off all 4 cabriole legs and wheels, and mounting the entire frame on the latest fashion: the platform rocker.
This frame was then heavily sprung, and a deep tufted leather "Turkish" upholstery was added, which created a fashionable and comfortable seat out of a chair that was a decade out of fashion. Even later in life, this chair had the central back panel of button tufting covered over in a matching flat leather panel. Probably more of an effort to "clean up the lines".
When it was brought to me, it had spent too many years in a garage with a bad roof. I was determined to restore the appearance to that of its first "conversion" about the time of the Civil War. This meant re-tying all the springs, adding fresh horsehair stuffing, muslin, webbing, burlap, and cotton to re-create the "Turkish" upholstery.
I have found a wide variety of materials to have been used in early upholstery. Some of these are hog and horse hair, Spanish moss, wood shavings, kapok, sisal, straw, rag wool, and, after World War II, foam. These are listed in order of quality from best (hog/horse hair) to worst (foam). I would never use any foam on a pre-industrial object. Early upholstery materials and methods must be preserved at all costs.
Shown is an example of an early seat, made up of webbing, burlap, hand stitched straw foundation, bleached horsehair topping, muslin, cotton batting and top fabric.
Another illustration is that of a hand sewn horsehair seat. Both of these examples were conserved in place by replacing only the rotted materials (like burlap and webbing) and keeping the original stuffing materials (like straw and horsehair). This guarantees that the "feel" and "look" of the upholstery matches the original design and intent.
I thought I should end with a photo of a nice Victorian gentleman's armchair with its upholstery restored and ready for fabric. This chair has had a much happier existence, and was able to survive with its legs and arms intact.