First Sample cont.
The first sample revealed other remarkable features when it was examined in cross section. The H-glaze is seen as the dark band running from the bottom left to the top right of fig 7. The white chalk substrate is bottom right and further surface nodules of glaze can be seen in the distance to the top left.

The first feature that we notice is the brown stain leaching into the chalk from the glaze. This is due to the migration of iron (Fe²⁺) cations and is the first stage of the rusting process. It merely tells us that the substrate had been damp - which we already know.

However, it can be seen that the ferrous glaze was tightly enmeshed into the surface of the chalk leaving no detectable gaps or openings. So complete was this union that the ferrous glaze even infiltrated into cracks in the substrate. Such an example can be seen in Fig 7. This is very strange as there seems to be no possibility that the larger crystals of the deposit could have migrated through the narrow crack, even if they were mobile enough to do so. All of the crack seems to have been infiltrated in this way as the aforementioned brown (ferrous) stain can be seen bordering the crack, even at its narrowest and deepest point.

Another feature of this sample has been the deposition of a thin layer of silicon and calcium compounds on the top of the mainly ferrous H-glaze. This too can be seen in Fig 7. This covering was almost complete, frequently mixed with fragments of glaze and, in places, quite thick (up to 100 microns). As the body of the glaze was relatively free from these impurities, it is not at all clear how these fragments of the substrate could have been transported to the surface of the glaze. This would certainly not have occurred if the H-glaze had been deposited on the chalk by any mundane mechanical means.