Iron Gall Ink

This is a great example of what iron gall ink can do to paper.  Can you see through the loss in the signature to the following page? 

It is also a great example of the difference in the stability of the two inks, the iron gall ink which was the predominant writing ink for many, many centuries.  And carbon black printing ink which was used in the days of movable type.

Iron gall ink is an acidic ink which worked really well when scribes were writing on parchment.  Parchment is a relatively thick and tough writing surface and the acid would sink into the parchment and make a very permanent, dark mark  Depending on how the ink was made (recipes abound) the ink could be more or less acidic.  This didn't matter so much as long as the writing or drawing was on parchment, but then the world switched to paper as the predominant writing surface and the ink proved too aggressive.

Iron gall ink is of significant importance to the conservation community because of its prevalence in archival documents, manuscripts and works of art. The ink corrosion website is one site that documents history and research related to this topic. 

Many different recipes were used over the years, and the stability of the ink varies according to the writing surface, storage conditions and handling.  Most book and paper conservators will have to make treatment decisions based on the condition of the iron gall ink they're dealing with.  In some instances, the ink is stable, and sometimes it has eaten through the paper.  There's the permanence of the written word and then there's permanence of the ink.