Making Joe Accetta’s idea work?
What is there to like in the experimentation being live-blogged in Can that weird and wonderful Turin Shroud be modelled? See my hands-on results with dye-imprinting, reported in real time?
Well, for one thing Colin is experimenting, not simply speculating. When Luigi Garlaschelli produced his manufactured images, he was immediately criticized for failing to match many if the shroud’s image characteristics. Luigi had failed. Colin is aware of that and he is taking the image characteristics into account. It is appropriate to note, however, that all of the image characteristics are not completely unchallenged; for instance, how certain are we that there is no image beneath bloodstains? Colin is aware of those issues, as well.
He begins this way:
For background, see the posting immediately preceding this one. It attempts to explain my switch in focus from the ‘scorch’ model to that proposed last year by Joseph Accetta – based on medieval dye imprinting technology. I’ve extended and embellished it a bit, but as the title indicates, this post is about getting ‘hands-on’ experience with dye impriinting off 3D templates, with a view to getting familiar with the pros and cons of the Accetta model, vis-vis the scorch model.
Oh dear. This is the reverse side, photographed straight afterwards, and already one can see bleed-through, despite the presence of that thickening agent. Late addition: the gum arabic was then left to evaporate in air until a treacly consistency, that was then painted onto the crucifix. despite the higher viscosity than used with dye, there was immediate bleed-through to the reverse-side of the linen.
Gum arabic is, sad to say, NOT the answer if one’s attempting to achieve contact-side imprinting only. Maybe there are alternatives that need testing, but they have to fulfil a number of criteria yet to be discussed in detail.
Maybe one needs to test a starch dispersion, or colagen glue from boiling animal bones etc? Suppose it imprinted well, with minimal bleed through. Suppose it was then prone to flaking off with ageing and/or handling, leaving that fainter ghost imagewhich is what we may be seeing today. There’s still work to be done. But first I must report the results of testing out a different scenario by which a ghost image could have formed, one that results in a modification of superficial linen carbohydrates, based on the premise that alum and/or iron sulphates used as mordants could have generated sulphuric acid that at sufficiently high local concentration to react chemically to produce changes not dissimilar to those obtained by thermal means (contact scorching). For that, the experiments moved from kitchen to garage, involving as they did a degree of hazard.