The Turin Shroud: How da Vinci Fooled History

The Turin Shroud: How da Vinci Fooled History was lent to me on my last photo trip so I had something to read on the train. The book is the research about how Picknett and Prince came to the conclusion that the Turin Shroud was not just a forgery ( as previously shown by carbon dating ) but that it was a primitive photograph created by Leonardo da Vinci.  Most of the book is not particularly well written and was a bit of a struggle to get through. They go into detail about the history of the shroud, and the various different theories regarding its creation. The book did become interesting in the penultimate chapter when they describe how they tried to create a similar shroud image using techniques da Vinci (in their opinion a skilled chemist, artist, physician, physicist, and heretic) may have used.

Their process involved producing a simple camera obscura with a primitive lens to project an image onto a piece of white linen. The authors thought da Vinci even used a model of his own face as that of Jesus. The image was fixed to the linen by coating it with a mixture of  chromium salts and an organic component such as gelatin, gum arabic or egg white. The mixture in areas hit by light became insoluble. Once the image had been projected onto the linen for many hours, the cloth was then heated. The fabric was scorched in the areas where the mixture had hardened. Areas of brightness in the original image now became dark producing the negative image you see on the shroud.

Another process done by Nicholas Allen was to coat the linen in silver nitrate or sulphate , project the image onto the linen then fix the image using ammonia.

The final chapter goes back to the rather less interesting debate over authenticity between the Shroudies and non-Shroudies.

If you found the Da Vinci Code or Angels & Demons fascinating then this book is well worth checking out. If you are interested in photography then chapter 8 is perhaps all you want to read.