These are early days, but I’m (how shall we say?) quietly confident.
— Colin Berry
Colin writes in his blog:
Here it is folks: the best I can offer after more than 3 years of almost non-stop experimentation : Model 9 ("the nitric acid model").
Alternative name (afterthought, added 25th April): this new technique produces what might be called a "tactile chemograph". Maybe there was only one ever produced (the image that we now call the Turin Shroud). The tactile chemograph may be thought of as a forerunner of the photograph. (In both instances, one produces a latent image from a real person without harming them in any way, one that can then be developed in a bath (or vapour chamber) with the appropriate developing chemicals.
There was the moment that Thibault Heimburger asked Colin to “explain in detail the advantages of your new hypothesis with regard to your ‘old’ scorch hypothesis.” Colin provided ten points. You should read them all. Here are two to temp you:
6. The technique allows for blood (or blood substitute) to be applied at the same time as body-imprinting medium, provided the blood or substitute stays red in nitric acid fumes (real blood does not – it quickly turns a brown colour). Blood would have been applied after. i.e. directly on top of the gooey imprinting medium to account for there being no body image under Shroud “blood”.
8. When applied to new linen, the technique has a side-effect that would be seen as a bonus – artificial ageing of the linen. Centuries later, pro-authenticity chemists and others would be delighted to find there was less potential vanillin and more mechanical weakness than would be expected of medieval linen a mere 700 years old.
Jumping to the conclusion (maybe, for there is no predicting with Colin):
The Turin Shroud. was this the world’s first and only tactile chemograph (think of it as a primitive ‘photographic’ negative, except for one tiny detail. Neither light not any other kind of elect6romagnetic radiation played any part in its production. It relied on the human touch (well, gentle massage actually).
What finally persuaded this blogger to abandon thermal scorching, and move to liquid (or semi-liquid) imprinting? It was that paper that Joe Accetta PhD presented at the St.Louis gathering, 2014, in which he propsoed that the TS image had been produced by woodblock imprinting. Up till that time I’d always been sceptical re the use of any kind of liquid imprinting medium, considering that would risk a reverse-side image. But I concocted my own equivalent of Joe’s "oak gall" imprinting ink, in which the iron salts probably have a mordant action, as well as creating the ink by reaction with plant tannins. Here’s an image produced, substituting tannin-rich pomegranate rind extract for oak galls, supplemented with iron (II)sulphate.
That ‘wet’ image was as good, if not better than anything produced by scorching. Yes. there was some reverse-side penetration, but might that not be minimized by suitable modification of technique, or simply by using thicker linen (and the TS linen IS thick, as Hugh Farey has observed).
Once liquid imprinting was permitted as an option, then a host of new experimental options were opened up. Thanks Joe Accetta. You weaned me of those thermal scorches (but they were useful in other ways, showing that ANY negative imprint can model certain key features of the TS, notably negative image and 3D-enhancibility). Models in science do not need to tick all boxes simultaneously. One can run different models in parallel, each earning its keep in one or other respect, while patiently waiting for the day when the super-model suggests itself, one that combines the best features of its precursors, not only mine, but those of Garlaschelli and Accetta in particular. Hugh Farey and Adrie van der Hoeven added some useful and thought-provoking grist to the mill too, though whether they and the previous two would approve of the end-result is another matter.
Might tactile chemography prove to be the super-model? We shall see. These are early days, but I’m (how shall we say?) quietly confident.
Oh oh! You can’t put the cork back in, can you?