Wednesday, November 5, 2008

Of Mice and Men and Foxing: Preserving Works on Paper


Years ago I spent several months collecting poppy seeds from various gardens that grew these plants. It was my intention to collect the seed pods and then create a garden showcasing the wide variety of poppies. I ensured that each little envelope or paper bag was appropriately marked with the common name as well as the botanical name of each variety of poppy seed it enclosed. I further stored the extensive collection in a cardboard box in my basement. Throughout the long British winter, I dreamt of the garden I would plant once the snow was a memory. I envisioned a summer and autumn paradise of color---all stemming from this beautiful flower.

When spring arrived, I went into the basement and was shocked to discover that at least one mouse had dined throughout the winter on the poppy seeds; none were left. This was my first real lesson in the importance of proper preservation techniques.

Several years ago I reinforced this lesson when I learned that some lovely watercolors I had framed previously were starting to develop brown stains in patches because the framer I had used failed to use acid-free materials. Prior to re-framing the works on paper, I was oblivious to the deterioration. The matte-burn was due to proximity to acidic window and back mattes and had yet to expand into the visually-exposed area of the paintings. Luckily, we caught it in time and the paintings were saved. However, I learned that it is vital that you work with a frame shops that use museum-quality archival framing techniques and materials, even if they seem more expensive than other framers. The additional money you spend will be a good investment for any works on paper that you value.

The stains/matte-burn on my paintings is often referred to as foxing because the color of the spots was said to resemble that of a fox's fur. The discoloration are a type of mold, often caused by metallic impurities in the sheet due to manufacturing. Foxing is an indication that the paper is acidic. The Mass Deacidification Feasibility Project Report : February 2001, a report by the British Library on acid deterioration of paper helps to elucidate the situation. Here is an extract of their report:

"The core constituent of paper manufactured before the onset of the Industrial Revolution was rag fibre. However, even though the final product was successful, the processing of rag fibre was costly and generally small scale. The supply of rags for papermaking became insufficient to meet the demands for paper brought about by rapid population growth and increasing literacy during the second half of the 19th Century.

With the increased output potential of industrial machinery and the developing knowledge of the use of a wider range of chemicals, a major change in the approach to paper manufacture took place. This change was to seriously affect the finished product. Wood pulp, literally macerated tree fibre, was chosen as a more widely available source material. A range of chemical treatments were incorporated to process the raw fibre - to encourage it to break-up, and to ensure the smoothness and colour of the finished product. Chemical wood pulp, as it became known, was produced from both hardwood and softwood chips.

It is true to say that the benefit of cheaper and much more widely available printed material, was immediately felt by the consumer, and contributed to the spread of knowledge in the industrial society. This cultural change was to significantly increase the scale of the acid paper problem.

Unfortunately, a combination of the inherently unstable chemical composition of the wood pulp fibre, plus the further chemicals added to the paper making process, all conspired to affect the long-term potential of the product and kick started this cycle of decay. Once this new paper product was exposed to light, heat, poor storage conditions and the high levels of Sulphur Dioxide pollution produced by the industrial age, the process of decay was accelerated.

The naturally deteriorating compounds within the paper structure then started to react to synthesise acids. In turn these acids started to work on the paper fibres, already shortened and weakened by the production process. The result is a discolouration of the paper (a darkening brown), and an embrittled quality to the sheet (or page). Even careful handling causes further deterioration and the material soon becomes unusable. Unchecked, this chemical deterioration continues until the sheet is completely destroyed, leaving only a pile of brown flakes. "

To remove foxing from paper, one can lightly dab 3% hydrogen peroxide onto the affected area using a cotton swab or cotton bud. Ensure you don't soak the spots and that you test the procedure on a less critical area of the paper---there is no sense in potentially destroying a valuable painting or other document such as a prized letter for the sake of bleaching out the foxing. Be aware that this method doesn't always work and it may be advisable to consult a professional conservation expert rather than attempt the task yourself.

Many people collect posters or newspapers of important historical events, such as the birth of a child, a wedding announcement, or the election of a world leader. It is important that special care be taken when preserving these documents for posterity. The US Library of Congress maintains an excellent resource of suggestions for document preservation at http://www.loc.gov/preserv/

Here are some basic recommendations on how to preserve historic front pages of newspapers or other important documents:

Store your document flat, out of direct sunlight and in low humidity, and not in anything plastic that can trap moisture because the papers are apt to become mildewed. The paper will be better preserved and survive longer if you invest in buffered, acid-free tissue paper to lay between sheets and front and back covers of a newspaper. This acid-free paper can be purchased at art supply stores or ordered online from archival storage suppliers. The Smithsonian offers a list of suppliers at http:www.si.edu/MCI/english/learn_more/taking_care/acidfree.html.

If you elect to preserve an entire newspaper, be aware you should use a tissue between each page, so the cost of preserving the document can become a bit pricey if you are saving more than simply the front page. Please don't be tempted to save money by using regular tissue paper, especially colored or one with print designs, as it will expedite the deterioration of the newspaper.


Additional preservation information:

There is no self-adhesive tape currently available which is archival. Because of this, try to avoid using all self-adhesive tapes as these will often fail or stain, and the adhesive becomes difficult to remove later. The glue and tape are also a favorite diet of insects, so it is wise to avoid it entirely.

Do not use paper clips or rubber bands to keep loose pieces of paper together.

Photos and works on paper should be stored in acid-free enclosures, made of either paper or card. Alternatively one can encapsulate them in mylar or polyester envelopes or in Melinex (a clear polyester film). Ensure that the storage containers are acid-free but do not contain PVC (Poly Vinyl Chlorides). Be aware that even acid-free paper may contain lignin, which over time will cause deterioration. Therefore, it is advisable to purchase paper that is both acid-free and lignin-free.

Learning from my lesson of the poppy seeds, choose storage locations which minimize exposure of your documents, posters, or newspapers to dampness, heat, air pollutants, dust, insects and vermin. When storing the boxes, ensure they are well above the floor, to avoid damage from potential water damage.

You may have noted that archivists and appraisers wear cotton gloves when handling paper items or valuable paintings. This is because the natural oils from your fingers can damage your papers. Follow their lead and only minimally handle your valued works on paper.

While one can't anticipate or prevent every potential type of disaster, you can take simple measures to retard deterioration and prevent damage by creating conditions optimal for the preservation of your prized works on paper, maps, posters or newspaper front page.

4 comments:

Designing Hilary said...

This is great information! And while I was reading it, my mind kept seeing metaphors for life throughout.

Dave King said...

A very comprehansive account, indeed. Valuable stuff, doing a great service. Thanks.

Grumpus said...

I have a few art items I've been wanting framed but have been bemoaning the expense. Your insights are timely. I didn't consider all the angles you've covered here, but now, armed with knowledge, I will stop being such a miser!

Sharon Hart said...

Grumpus, I'm glad I could be of help to you. If you value your art, don't make the same mistakes I've made in the past---work with a reputable framer and ensure you use acid-free materials. Then you can enjoy the work for years!