Let’s look at sheet protectors first. In terms of archival safety this refers to the ability the sheet protector can effectively protect whatever it is that you are storing inside, whether it’s documents or photographs. This might sound very simple and on a general level, you may assume all sheet protectors should be able to do just that. However, on a more technical level, you will find out that in fact not all sheet protectors are archival safe. In order to be actually archival safe, sheet protectors should be chemically-stable with a neutral or slightly basic pH level. In science, pH levels refer to how acidic or basic something is. So with a neutral or slight basic pH level, that means sheet protectors should be ‘acid free’. This is important because being ‘acid free’ means your documents won’t be damaged by any erosion that may happen to the sheet protector over long periods of time.
Having said that, now you might be asking the question “With all the sheet protectors out on the market, how do I really know if they are acid free or not?” The answer to that question is - materials. There are several types of materials that are used to make sheet protectors:
- Polyvinyl chloride (PVC)
- Polyethylene (PE)
- Polyester (Mylar)
- Polypropylene (PP)
So Why Not PVC?
The reason why PVC is considered non-archival safe is because it contains plasticizers. Plasticizer is a substance that is added to PVC during production to increase its flexibility and durability. There are over 300 different kinds of plasticizers - 50-100 are used commercially. These plasticizers will emit damaging hydrochloric acids as it deteriorates, therefore ruining both the sheet protector and the document inside. If you place photographs or other important documents into PVC sheet protectors, overtime you might notice damages like colors or ink from the photo and documents sticking to the sheet protector. This is a disastrous scenario as it is almost impossible to restore a photo with its color faded or ruined by acids emitted from the plasticizers used in PVC sheet protectors. Remember, PVC sheet protectors are NON-ARCHIVAL SAFE and should be avoided at all times.
The two images below shows exactly how PVC sheet protectors can cause irreversible damage. As you can see from the image on the right, the red ink on the paper had faded. On the left you see the PVC sheet protector with the red ink marks from the document. What happened is basically the paper got stuck to the sheet protector and when you try to take the paper out, the ink is 'pulled' from the paper onto the sheet protector. This can be a disastrous situation if you have precious memorable photos placed in PVC sheet protectors and over time they can be ruined just like this document.
- PVC sheet protector and document ruined
On another note, PVC is also used to make things like toys, clothing and other daily applications. There have been reports that show some plasticizers have a high level of toxicity in them and may even be a cause for cancer, therefore raising considerable amount of health concerns. Some countries even ban the use of PVC. While it seems like the plasticizers used in PVC for sheet protectors are not as dangerous, it is still something to keep in mind.
So What is Archival Safe?
As mentioned early, of the four types of materials, only polyethylene (PE), polyester (Mylar), and polypropylene (PP) are archival safe. The reason is because they do not contain plasticizers and in general have a neutral or slightly basic pH level. This means they are acid free and is important because remember, acids will cause damage to paper causing them to turn yellow and become brittle and fragile.
So now you might be wondering, if all three materials are archival safe then which one should you use? The answer to that is it depends on what you need the sheet protectors for.
Polyethylene sheet protectors are the cheapest of all three. However, the quality of the sheet protectors is not that great. They usually are softer, less durable, and their finish is not as clear so it makes it hard to read the document that is inside. If you’re in need of cheap sheet protectors just to store regular paper and don’t mind poor quality then polyethylene is your kind of sheet protector.
Polyester, or Mylar, on the other hand is the most expensive kind of all three. In fact, it's so expensive to manufacture, only a hand full of companies actual offer polyester sheet protectors. Being so expensive, of course you should expect to get high quality sheet protectors that are durable, have a great feel and texture to it, and are crystal clear so it makes it very easy to view the contents inside. These are the sheet protectors you get if you want to protect and showcase your artworks, and of course if you have the money to spend.
The last type, polypropylene, is probably the most ideal sheet protector type. They are economical and comes in good quality –durable, clear and of course, again, archival safe. They are the most common type of sheet protectors used today and note that all Keepfiling sheet protectors are made from polypropylene.
Keepfiling is not only about organizing but also about protecting your documents and offers the best archival safe documents. Check out our sheet protector buying guide and our archival safety page to learn more about sheet protectors and become an expert yourself!