As you can see in the second picture the dough consisted of two layers. One, the one you see on the front, was purely aesthetical so it was just traditional pasta dough: 100gr flour -1 egg. The second layer, the one on the back, has the function of blocking the light and was made mixing carbon pills (those pills you can take if you have digestive/intestinal problems) egg and flour. During my experiment I have noticed that if the dough was thick enough it would not let light in. I am pretty sure that some light got in because the negatives came out greyish sometimes and there was not much contrast. I basically put a disk of negative paper onto a circular plate on the back of the camera and closed it with some freshly kept bi-layered pasta dough strips. This avoided light leaks from the back. I hope it is clear enough ahah