A 2.1. Holes
A 2.2. Hair remains
A 2.3. Striations
A 2.4. Traces of jagged action
A 2.5. Veining, vein evidence, drainage of blood vessels
A 2.6. Variation in thickness
A 2.7. Opacity, transparency
A 2.8. Splitting
A 2.9. Variation in colour or surface appearance, matte, semi-matte, glossy
A 2.10. Presence of grain layer
Areas of the parchment with vascular patterns change its appearance.
In raw skins, the networks of blood and lymphatic vessels and diameters of the vessels can vary from layer to layer. To produce high-quality parchment, it is important to clearly drain the raw skins before processing. Draining the blood from the finer blood vessels is a job that requires great care and effort.
In high-quality parchment, the blood vessels are light in colour when viewed under transmitted light. Residual blood in the blood vessels (iron salts in the blood) can cause significant damage to the parchment later on. As a result of sloppy processing, the blood residue left in the vessels darkens the blood vessels and it is clearly visible when viewed under transmitted light. The residual blood causes the parchment to degrade and stiffen.