Note the comment: "Aside from foxing, other types of age-related paper deterioration include destruction of the lignin by sunlight and absorbed atmospheric pollution, typically causing the paper to go brown and crumble at the edges, and acid-related damage to cheap paper such as newsprint, which is manufactured without neutralizing acidic contaminants."
Apparently the US constitution is stored in a sealed container filled with Argon gas and will survive like that for centuries (away from sunlight). I'm guessing it's the same Argon they use for welding?
Well, I got a response to my questions from the Northeast Document Conservation Center:
Charlie said:
Hi,
We have had an interesting situation pop up in the Movie Poster hobby. A fellow collector had linenbacked posters from different restorers all stored in the same room and presumably the same humidity. Posters from a certain restorer exhibited foxing versus others after 10 years. It is common practice (some accept, some don't) to use wall paper paste, probably with antifungi. The collector is claiming that all the posters backed with wall paper paste are foxing free, while the ones that show foxing from the same restorer were backed with wheat paste. So we have two theories. Wheat Paste vs. Wall Paper Paste and this one restorer vs. all others. Many restorers use wheat paste in our hobby - I use it on my own projects. I am suspicious that a hygroscopic adhesive or chemical was used in the backing process that is accelerating the absorption of water from the air. Two questions. 1. Opinion on wall paper paste. 2. If there was an adhesive or chemical which could be causing the foxing, which would it be? What effect does microbes, from say storage or use of tap water, have once paper is dry and then rehumidified?
These are all very good questions, however, with rather complex answers. Let’s begin with the storage environment.
High humidity, high temperature and excessive light levels will accelerate the deterioration process of all paper based artifacts. A high humidity environment would be in excess of 65% RH, and a temperature greater than 72 degrees Fahrenheit and at these levels mold can start to grow. Light exposure levels should be no greater than 20 foot-candles to prevent fading. Museum exhibition spaces are usually maintained at 10 foot-candles. In private homes or studios, maintaining ideal storage and exhibition environments is very difficult but these factors influence the material stability and help control mold formation. Technical information on environmental guidelines can be found on the NEDCC web site:
Is commercial wallpaper paste better than wheat starch paste? The simple answer is “no.†Commercial wallpaper paste is usually proprietary so you do not know what is included in the formulation. The main component is usually a cellulose ether such as methyl cellulose. There may be unknown additives that may work just fine with contemporary wallpaper but not necessarily with paper base artifacts with redeeming value. Most commercial wallpaper pastes will have a fungicide incorporated in its mix. Any unknown additives with poor aging properties can cause paper to deteriorate and discolor so it is vital to know what is being used and how it will react with the paper, inks and colorants.
Conservation grade cellulose ethers and their equivalents go by names such as Methocel®, Ethulose®, Cellofas®, etc. We do know the composition and aging properties of these cellulose ethers and that is why they are used in the conservation profession. Cellulose ethers are less prone to develop mold than wheat starch paste but both types of adhesives are hygroscopic.
Wheat starch paste is a proven adhesive that has been used for centuries in Japan and China for mounting scrolls and creating screens. The aging properties are excellent and it is reversible, however, in a poor environment it can be a source of food for mold and insects. So the bottom line, using wheat starch paste and the formation of mold cannot and should not be a reflection on the quality of work of one restorer or conservator over another.
It is the obligation of the collector to properly house their collection in the best environment suitable for their artifacts and to protect the material.
What is foxing? Technically, foxing is referred to localized spot stains that develop from metal inclusions in the paper when it is first made. Hollander beaters were often the main source for small metal fragments that were cast along with the paper fibers to form the sheet. As the metal corrodes the corrosion products then stain the paper often a rust brown similar to a fox’s fur color.. The term foxing is often used interchangeably to also describe spot stains from mold.
Any moisture used during a treatment step, which by the way should only be performed by a trained individual, should be filtered, distilled or deionized to ensure there are no particulates, chlorine, soluble metals or organic material in the water that will result in any adverse reaction or deteriorate the object. Use of any poor quality repair materials, pressure sensitive tapes, non-reversible adhesives and improper repair techniques would be irresponsible.
If you require any additional information please let me know or you can visit our web site at www.nedcc.org.
"Any moisture used during a treatment step, which by the way should only be performed by a trained individual, should be filtered, distilled or deionized to ensure there are no particulates, chlorine, soluble metals or organic material in the water that will result in any adverse reaction or deteriorate the object."
The restorer probably did not use conservation safe water - probably straight from the tap without filtering or did not boil the water to remove microbes.
And water PH directly from a tap is also slightly alkaline around 8.2+ so hardly neutral, shouldn't tap water be buffered to bring it down to as close to 7 as possible?
And water PH directly from a tap is also slightly alkaline around 8.2+ so hardly neutral, shouldn't tap water be buffered to bring it down to as close to 7 as possible?
My first instinct is to say no, the higher the better. For example the deacidifcation solution is 10 - 12. You could have an issue with shocking the paper with too much alkalinity. Just have to test your water I guess.
But Alkaline liquids must cause more damage as they set off reactions with other chemicals/elements, I thought the idea was to get everything Neutral, Tap water runs alkaline otherwise the Pipework to houses would rot faster due to the water being acidic.. Linen-backing is much more complicated than it first seems.... :-?
Alkaline Reserve - an alkaline substance often added to paper storage materials to counteract the acids that may form in the future and to help absorb acids from artifacts. Alkaline buffered storage materials usually have a pH of between 7.5 and 9.
Although simple water washing reduces acidity, the addition of an alkaline buffer to paper is sometimes recommended. This is appropriate for papers that will be subject to acid hydrolysis even after washing, acidic papers that cannot be washed, and acidic papers that will be encapsulated. Sometimes alkalization is achieved by immersion in an aqueous solution of an alkaline substance such as magnesium bicarbonate or calcium hydroxide. If water-soluble media are present, the artifact may be treated nonaqueously with an alkaline salt dissolved or suspended in organic solvent. Nonaqueous solutions are usually applied by spraying. While the addition of an alkaline buffer is often beneficial, such chemicals may cause alteration or even damage to certain components of a work of art. Some colors, for example, may change if subjected to alkaline conditions. This change may be immediate or may occur over time. For this reason alkalization is not recommended for all materials. Like all conservation procedures, the decision to alkalize must be made on a case-by-case basis and should be left to a qualified conservator.
I was interested to read Michaels email and I have the following comments,
1. There is not a humidity issue in my storage facility so that is definitely not the problem. There are no windows so light is not an issue.
2. Wheat Paste v Wallpaper Paste. Surely it is dependent on how the restorer mixes the wheat paste. Each restorer would have different methods and some would be more careful than others with the wheat paste. The wallpaper paste that many restorers use comes already mixed in large drums so maybe there is less likely to be a problem with the wallpaper mix.
3. Michael says that wallpaper paste may have "poor aging properties can cause paper to deteriorate and discolour". This would indicate that there is some risk in using wallpaper paste which is interesting because many of the biggest restorers use wallpaper paste by the drum.
4. "It is the obligation of the collector to properly house their collection in the best environment suitable for their artifacts and to protect the material." I have never had any restorer give any advice or notice on how posters should be stored after they have been backed. Maybe they should do this as a form of "disclaimer". Most people who have posters linen backed do not think that there might be a risk of deterioration.
Getting back to my original article that prompted all of this, I have to reiterate that, amongst all of the linen backed posters that are in my warehouse, the only ones with the foxing issues were backed by one restorer. So far, I have seen nothing that changes the opinions that I expressed in the article.
“There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.â€
If the opinion of a Director from a National Conservation Center won't do it, nothing will. It's all that there is John. It's the restorer, not the product.
“There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.â€
If the opinion of a Director from a National Conservation Center won't do it, nothing will. It's all that there is John. It's the restorer, not the product.
Well, that's what I have said all along. The restorer used wheat paste. He must have done something wrong in mixing the paste that resulted in the foxing issues. The "product" he used was defective.
That is all I was saying! I just don't want wheat paste to become the culprit...
Actually John, you ended up editing your first response after my initial respons. It is not the product (wheat paste) but the restorer. Wheat paste is a perfectly acceptable adhesive for conservation.
I don't want to blame the wheat paste but I have a couple of questions for you about this.
Are there different kinds of wheat paste and different methods of mixing it? Obviously, the water that is used is also important but how easy do you think it is for a restorer to make mistakes in mixing the paste?
There are different types of pastes. There are very natural types of paste where you would by wheat or rice starch from the local grocery store where you could prepare an adhesive. There are purified chemistry grade wheat pastes like what I use from talas called AYTEX-P. There are basic pre-cooked wheat pastes and highly refined pre-cooked Japanese wheat pastes.
The only concerns I see with wheat pastes being prepared wrong, most likely wouldn't result in mold growth but poor adhesion, i.e. your poster becoming unhinged from the masa or masa from canvas. One thing I know people don't do is soak the wheat paste before cooking it...
However, just like any natural product if not stored properly it can spoil - as I said develop microbes. I am still unsure whether these microbes are dormant when dry and then reactivated my humidity or not... But it would make since that this is a possibility. It is highly likely that your restorer did not prepare the wheat paste with a conservative appropriate water source. He probably just turned the tap (or faucet) and expected the cooking of the wheat paste to disinfect the water which it would not since it does not boil... You need to bring to a rolling boil water for at least a minute to sterilize water and even that does not remove any soluble metals etc... So it needs to be purified and boiled...
I am semi working on an experiment now as I have kept a batch of wheat paste in the fridge since November of last year just to see what will happen when I take the lid off... Ewwww...
I would imagine the restorer didn't have any idea he would create the situation you are in... I myself hope that 10 years from now Matt isn't telling me that weird brown spots are showing up on his posters.
You just never know... All a restorer can do is follow sound researched principals and go from there.
Your comments really reinforce what I have been saying. If a restorer uses an inferior paste and/or doesn't get the mix right then there could be future problems.
By the way, anyone is welcome to add any comments to my article so that other views can be expressed.
Comments
Although simple water washing reduces acidity, the addition of an alkaline buffer to paper is sometimes recommended. This is appropriate for papers that will be subject to acid hydrolysis even after washing, acidic papers that cannot be washed, and acidic papers that will be encapsulated. Sometimes alkalization is achieved by immersion in an aqueous solution of an alkaline substance such as magnesium bicarbonate or calcium hydroxide. If water-soluble media are present, the artifact may be treated nonaqueously with an alkaline salt dissolved or suspended in organic solvent. Nonaqueous solutions are usually applied by spraying. While the addition of an alkaline buffer is often beneficial, such chemicals may cause alteration or even damage to certain components of a work of art. Some colors, for example, may change if subjected to alkaline conditions. This change may be immediate or may occur over time. For this reason alkalization is not recommended for all materials. Like all conservation procedures, the decision to alkalize must be made on a case-by-case basis and should be left to a qualified conservator.
I was interested to read Michaels email and I have the following comments,
1. There is not a humidity issue in my storage facility so that is definitely not the problem. There are no windows so light is not an issue.
2. Wheat Paste v Wallpaper Paste. Surely it is dependent on how the restorer mixes the wheat paste. Each restorer would have different methods and some would be more careful than others with the wheat paste. The wallpaper paste that many restorers use comes already mixed in large drums so maybe there is less likely to be a problem with the wallpaper mix.
3. Michael says that wallpaper paste may have "poor aging properties can cause paper to deteriorate and discolour". This would indicate that there is some risk in using wallpaper paste which is interesting because many of the biggest restorers use wallpaper paste by the drum.
4. "It is the obligation of the collector to properly house their collection in the best environment suitable for their artifacts and to protect the material." I have never had any restorer give any advice or notice on how posters should be stored after they have been backed. Maybe they should do this as a form of "disclaimer". Most people who have posters linen backed do not think that there might be a risk of deterioration.
Getting back to my original article that prompted all of this, I have to reiterate that, amongst all of the linen backed posters that are in my warehouse, the only ones with the foxing issues were backed by one restorer. So far, I have seen nothing that changes the opinions that I expressed in the article.
Charlie
I don't want to blame the wheat paste but I have a couple of questions for you about this.
Are there different kinds of wheat paste and different methods of mixing it? Obviously, the water that is used is also important but how easy do you think it is for a restorer to make mistakes in mixing the paste?
"There are different types of pastes."
Your comments really reinforce what I have been saying. If a restorer uses an inferior paste and/or doesn't get the mix right then there could be future problems.
By the way, anyone is welcome to add any comments to my article so that other views can be expressed.