Re: [Marbling] Is acid-free paper still acid-free after alumming?
- Much of the problem with the deterioration of paper in the past 150 years can be attributed to manufacturing issues. Wood pulp replaced cotton and linen as the primary fiber source and at that time the wood pulp contained lignins, which turned out to be destructive to the paper over time. In addition rosin and even alum was added to the pulp as sizing in the latter half of the nineteenth century, both of which, in combination are destructive to paper. The combined destructive potential of all these items is what gives 19th century paper its bad reputation. Pulp used for paper nowadays is purified ("high alpha cellulose") and good quality paper, today, will often indicate that it is "lignin free", and the other two items are no longer used as fillers/sizing. The alum used in marbling may slightly alter the pH, but I have never read or seen that it alone is sufficient to lead to the deterioration of paper. There is always the concern that the degradation of alum to sulphuric acid over time will shorten the life of the paper, but if this is a real issue there are other mordants that can be used. Aluminum acetate, although more expensive, is a good option and one Joseph Halfer felt preferable to Aluminum sulfate or Potassium aluminum sulfate. It does work quite well. Retention agents, which are used in paper fabrication for holding pigment in the pulp for colored paper, can also be applied to the surface of the paper for marbling (the process is a little more difficult than working with alum but also works well). These agents do not acidify the paper at all, rather their binding ability is based upon positive/negative attraction of the pigment to the chemical. This bonding is weaker than the chemical bonds occurring with alum, and so the papers have to be treated a little differently, but they are an option for someone concerned about the potentially destructive capability of standard alum.
----- Original Message -----
Sent: Saturday, August 11, 2007 9:57 PM
Subject: [Marbling] Is acid-free paper still acid-free after alumming?
This question has surfaced from customers at the gallery. I am not
sure of the answer & am hoping from expertise in the forum. When
beginning with acid-free paper for marbling, alumming with aluminum
sulfate, marbling in a carragheenan size & then vigorouly rinsing,
does the alum get removed? Does the paper return to an acid-free
status? Bookbinders, collage artists & even serious scrapbookers
question the acid-free condition of the marbled papers. I want to
provide accurate information. Any info?
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