Even today, there is no shortage of Christ’s blood. It is preserved in reliquaries in Italy, France and Europe, and is even available for sale, for about £5000.
From russianstore.com, whose selection changes regularly.
And this, it should be noticed, is not blood collected from statues or pictures that drip miraculously at certain times of the year, nor is it blood that appeared miraculously from a consecrated host, either still preserved on the wafer or collected as it dripped onto the corporal beneath. There are many more of those. No, the examples above are direct from the suffering body of Christ, staining his seamless robe, dripped onto the soil beneath the cross, or collected by Joseph of Arimathea in the Holy Grail. Or Nicodemus in a glove.
It is not at all surprising that a cloth purporting to be the burial shroud of Jesus is stained with real blood, although to be honest, like all the rest, it would be astonishing if any of it was the blood of Christ. The earliest signs of interest in the ‘precious blood’ seem to appear in the 10th century, and exploded into the Late Medieval ‘frenzy’ described by Caroline Bynum in her book, Wonderful Blood (Bynum, Caroline Walker, Wonderful Blood: Theology and Practice in Late Medieval Northern Germany and Beyond, University of Pennsylvania, 2007). Paintings of the crucifixion showed blood dripping from the nail wounds, spurting from the lance thrust, and dribbling down arms and legs into the ground. Images in manuscripts were drenched in red, and whole prayerbooks were spattered with it on every page.
Prayers implored the opportunity to get drunk on Christ’s blood, to suck it from his bleeding feet and wallow in his wounds, for shelter, cure and sustenance.
Blood of Christ, make me drunk […] Hide me in your wounds. (Anima Christi, 13th cent).
I suck the blood off his feet; that suck is so sweet […] I hug and I kiss as if I were mad; I roll about and suck for I know not how long, and when I have finished yet still I lust for more. (A Talking of the Love of God, 13th cent.)
From this perspective, the blood on the Shroud of Turin seems positively restrained. If, however, it was originally manufactured for liturgical purposes, rather than simple veneration as a relic, then the blood would almost certainly have been added when it was repurposed, possibly years after its original use. This runs into conflict with the endlessly repeated authenticist trope, that the evidence shows that the blood preceded the image on the cloth. “There is no image under the blood” goes the cry, mostly from people who have not read the evidence, or understand its fragility.
It relies entirely on a finding by John Heller and Alan Adler, in their crucial paper, ‘A Chemical Investigation of the Shroud of Turin’ (Journal of the Canadian Society of Forensic Scientists, Vol 14, No 3, 1981). It was their opinion that the coloured fibres of the Shroud all showed some degree of “corrosion”, from ‘non-image’ (minimal), through ‘image’ to ‘scorch’ (maximal). They do not mention ‘serum’ or ‘blood’ fibres in this respect. However, they go on to report various enzymatic tests, most successfully using protease. This apparently dissolved all the coatings from ‘blood’ and ‘serum’ fibres, but had no effect on ‘image’ fibres. “Interestingly, fibrils freed of their coatings using this technique closely resemble the non-image fibrils when viewed under phase contrast.” The implication is that since the image fibres are “corroded”, and there is no “corrosion” under the blood and serum, there is no image under the blood. However, this finding does not take into account the possible effects on the image of the blood or serum when they were first applied, or when they were removed. Furthermore, the idea that the image on the Shroud was derived from ‘corrosion’ of the surface of the fibres was rejected by Ray Rogers, in favour of the ‘encrustation’ that he observed. He also noted that while the Shroud itself fluoresced under ultra-violet, the image suppressed this fluorescence (Rogers, Raymond, A Chemist’s Perspective on the Shroud of Turin, at shroud.com, 2008). This gives us a test for the “no image under the blood” hypothesis. Where the blood has clearly eroded away from the cloth (as is clearly shown in some of the stains at the back of the head, for example), if there is no image, the cloth will fluoresce as brightly as the background, but if there is image, it will not.
Here is the back of the head, an area of intense image and intense blood:
By visible light By ultraviolet light
We may certainly note that on the UV photo there seems to be a fringe around some of the stain which is brighter than the area round about. This has been attributed to blood serum, although lemon juice (an anti-coagulant) also fluoresces. However, within the borders of the bloodstains, where the blood has clearly been eroded away on the visible light image, there is no indication of the brightness of the unimaged cloth.
Can this be reconciled with Heller and Adler’s ‘corrosion’ observations? I think it can. The image chromophore, whatever it is, although it weakens the surface of the fibres, does not corrode them. However, time and age have damaged those exposed to the air, the weaker the fibre, the more the damage. Image protected by blood, however, has not suffered this damage.
For these reasons I see no difficulty in supposing that an image originally envisaged as in the noble repose of death could be repurposed dramatically to depict the sufferings of Christ, as a relic, and concomittantly as an object of ecstatic veneration. It is not impossible either, that the blood was originally just paint, but was supplemented by the real thing when the cloth became a relic.