Preserving a Document with a Seal

Dear Donia,
What is the best way to preserve a document with a Pope Pius XII papal seal?

Pope Pius XII papal seal

Q. Dear Donia,

I have found an old blessing from Pope Pius XII. It has the papal seal, and I found it between the pages of an old Bible. The edges are tattered but the heart of the document is in fair condition and readable. It is slightly protected by a yellow document protector. What is my best course of action? Thanks, Robert

A. Dear Robert,

What an exciting find! Your best course of action depends on what you would like to do with it.
If you want to display it, it may be that you would have to do nothing but get it properly framed.  Be sure to look for a framer who will use archival mat board and techniques. Most likely, you will have to go to Rochester or Buffalo for this.  
The best mat board to look for is what we call museum rag board.  It comes in many shades of "white" and you should have not trouble finding one to match your blessing. Before going to a framer , please take a look at the helpful leaflet from the Northeast Document Conservation Center on "How to Do Your Own Matting and Hinging." This helpful guide will give you the information you need to ask the right questions. 
As for the glazing, you will want to look for glass or Plexiglas that has UV blocking properties. TruVue glass and Acrylite plexi are two examples. Choosing between glass and plexi depends on what you want. Glass will be clearer, hold less of a static charge, and be more resistant to scratching but is heavier.  
If you simply want to store it, if it is stable apart fro, the tatters on the edges, the blessing can go into an archival (acid-free, lignin-free, buffered) folder. If the blessing's tattered edges are fragile, brittle, or breaking off, it can be put into polyester sleeves for safer handling.  These materials can be purchased through our sponsor, Hollinger-Metal Edge.
The best practice for storage is to keep the blessing somewhere in the main part of your house. Attics and basements are poor choices because the environment will increase the rate of deterioration, not to mention the risk of pests and flooding.
I hope this helps and if you have any more questions, please don't hesitate to ask Dear Donia!