A Collector’s Chemistry Lesson:


Sometimes the things you might use to protect your collection might

actually do damage. Here is some advice on acid free and archival

safe materials.


What a complicated subject this is!  First off –it might be helpful to sort out the difference between things that are made to be archival and things that are made to protect things of archival value.  For example, the paper you buy on sale at the office supply store to run through your Xerox machine or printer is NOT archival.  But an expensive piece of art had better dang-well be painted or printed on a piece of paper that you can count on being around for a long time. 

On the other side of the coin, there is the stuff you use to protect / store / display valuable stuff.  Key word here is “protect.”  Suppose you carefully tuck your collectable away in a nice cushy bed of whatever and put it safely away for years and years.  Then you take it out –or let’s be frank here- your heirs take it out even more years down the road- and find that the stuff you so conscientiously used for padding has dissolved into ugly goo and smeared itself all over your item.  Your valuable collectable held up perfectly, but is now worthless –or certainly less valuable.  This is actually the topic I need to address in this article, but a few words on archival materials is in order –then I move on-to protecting collectibles with archival SAFE methods.


Everyone has heard of “acid free” and it sounds like a good thing.  Acid is –after all- corrosive –it can burn you and this must be a bad thing.  But it turns out that everything is acid.  Or alkaline –which is the same thing –only the complete opposite.  Your body is acid –slightly.  All fruit juice is acidic, carbonated beverages –by virtue of that carbonation over-and-above the fruit juice- is acidic.  Vinegar is a good strong acid –“acetic acid” by name. Lemons make you pucker-up because of citric acid –chemically right next to ascorbic acid -better known as Vitamin C.

So why is acid in certain things bad –and conversely, why is ‘acid-free’ a good thing?  Near as I can tell. Things that get manufactured –paper for instance- are easier to manufacture if they have some chemistry done to them.  Acid is certainly a sub-set of chemistry.  You didn’t learn about acid in your HS American Literature class did you?  My point here is that things that are pretty much the way God made them are safe from self-destruction from the acids they contain.  (This is not to say that there are not other ways for them to get messed up –remember from my article on Bio-Hazzards that if God made it, He (She?) also made something that eats it.) 

But wood is probably not going to turn yellow and brittle like a cheap paper-back book.  A real butterfly is not apt to curl up and crack like a decorative plastic one.  An oil painting (linseed oil & ground mineral pigments on cotton or flax fabric) is not going to fade the way a poster does (made with cheap paper and printed with quick drying organic inks.) 

So what do you do if you have something you value and want to have around for a long time, but you are not sure it’s made out of archival materials?  Actually, there is not much you can do.  Ask questions when you buy it, but does the seller look like they know their chemistry?   There is one possibility.  There are de-acidification sprays made to spray on paper (and photographs).  Such things go on wet and do chemistry to your collectable.  Are you a little hesitant to spray some chemical goo all over a valuable document or image?  Don’t blame you.  

One expert –Dennis Smith of Archival Methods* says that such things in the hands of a casual user can do more harm then good.  If it’s this valuable, you would do well to go to a pro who knows the chemistry.  But before you even do this –you must ask yourself if you have done all the other things a collector can do to protect his or her collection, and I have written on these subjects.  UV Light Protection, Using Desiccants and, Protection from BioHazards might be better places to start.  And this brings us to…


This side of the coin deals with storing and protecting your valuable items in a manner the actually protects them.  Let me give you an example of how NOT to do it.  This is a direct quote from a nice lady –a curatorial expert actually- who helped out when I wrote my article -A Visit to the Fabric Store:

"And velvet, well, my opinion is still bad, bad, bad. Velvet and silver is a 500%   Don't Do It.--you will have hundreds of etchings over the surface that look as if tiny worms had burrowed just beneath the surface--and they're not fixable.  Saw it firsthand once, and it was amazing."

Imagine that –you work very hard to protect something you cherish –with velvet –soft luxurious velvet even –it’s padded and tucked away safely and one of the very things you do to protect it –ends up ruining it! 

So what to do to protect your collection –the way the museum professionals do –the guys with advanced degrees and who can spell CHEMESTRY with out getting help from SpellCheck every-dang-time.  A little vocabulary might be a helpful way to start out.   



A plastic that may be good (tri-acetate) or bad (di-acetate). 


Means just that.  But you also need to know about…

Acid migration

If something that contains no acid is stuck closely enough to something that does contain acid –the acid moves into the acid free thing.  The moral here is to be careful of what you stick the valuable thing into / onto / next to.


Good plastic for archival undertakings.  Stiff, clear and chemically stable.



The opposite of acid and probably a good thing.  Unless it’s a bad thing. 


A unique sort of chemical thing that is the opposite of both acid and alkaline –it neutralizes –or ‘buffers’ both.  (And if this confused you –find yourself a chemistry teacher to explain it ‘cause it don’t make a lick of sense to me either.)


A material capable of absorbing moisture from it’s surroundings.  This can be good or bad.  Desiccants are hygroscopic on purpose.  Paper is hygroscopic to some degree –can’t be helped- and as such, paper may come to be nourishing to fungi and mildew.  BTW both hops and alcohol are hygroscopic and absorb water from places like your brain and the lining of your bladder, which makes it smaller. Don’t need to discuss the later effect –but a dehydrated brain is a large part of what is called a ‘hang-over.’


A component of wood fiber that breaks down into acid.  The good news is that most of the lignin is taken out of most paper –except newsprint. Archival safe materials are almost entirely “lignin free.”

Mylar & Melinex

Different trade names for the same absolutely inert and absolutely vapor-proof plastic. It has archival value in protecting things from atmospheric nastynesses.



(Cool word!  Has a scientific edge to it and is useful for insulting people who are too full of hot air.)   This is the tendency for some things to slowly emit various damaging gasses.  See…..



Stuff in plastic that makes it more flexible.   Plasticizers tend to evaporate / ‘volatilize’ / ‘out-gas.’  All this means that some plastics emit ‘goo’ that can mess up the things you store in them.   A discussion of the good plastics and the bad plastic would quickly degenerate into something very like a graduate level organic chemistry class so –for the time being- if it smells like a cheap new shower-curtain- you are smelling the evil plasticizers and this is a bad thing.)



Most plastics start with the word “poly” and go downhill from there.  In general, the good plastics for protecting valuable things are polyester, polypropylene, and, acrylic. (They don’t smell.)  



Now this is curious, but after longish introduction and bothersome vocabulary lesson, I have comparatively little advice for you.  Too much stuff gets itself collected and there is too much variation between what it’s made out of.  None-the-less, consider the following:




The folks at Gaylord Brothers take this business pretty seriously.  They also offer an absolutely excellent on-line (free!) book on simple techniques for the maintenance and  repair of books  -BOOKCRAFT.


*Archival Methods is a good company, with helpful people and a web-site you need to see.

Art-Care is is where to go to find out where and how to spend money -but it also has excellent information and experts.

This site is from Stanford -and when has Stanford ever made anything easy?  None-the-less, it's where I found many of the articles listed above.  Check out American Institute for Conservation of Historic and Artistic Works