Hugh Farey writes as a comment:

image“Edgerton linen” was hand-produced by a Kate Edgerton, from plant to woven cloth, and then, much to Ray Rogers’s chagrin, ironed, which made it go yellow, so he soaked it in hydrogen peroxide to bleach it. He hoped, and was probably correct, that this had no effect on his subsequent experiments. Although the linen is descibed as prepared “following the methods used in the Near East in Roman times,” no details are given in “A Chemist’s Perspective on the Shroud of Turin.” I have acquired some quite stiff unbleached linen, however, and am prepared to give it a try, using leaves from soapwort mashed in water as a source of saponin, and commercial dextrin (a readily available water-soluble glue) as the starch. I also have ammonia and urea. The problem is “freshly dead” animals. The trouble here is to acquire enough for sufficient repeatable experimentation. However, after asking around, I find that people who keep snakes as pets feed them on frozen mice, which are available quite cheaply in bulk. This looks promising, so I’m preparing an appropriate protocol for just the experiments you suggest!

imageIncidentally, although my linen feels quite stiff and heavy, it has an areal density of only 16mg/cm2, which is considerably less than the Shroud, which therefore appears to be considerably thicker than I had previously imagined. As such, I think it will be much easier to produce discolouration on one side of the cloth only. Other investigators (Thibault? Colin?) might be able to comment further on this, and readers of this blog might like to weigh a bed-sheet themselves to confirm how flimsy it is compared to the Shroud.