Note: The word mezuzah always refers to the scroll, and the case or cover is always referred to as such.
Every mezuzah should be wrapped in a protective wrapping before it is placed in a case. Wax paper, parchment paper, thin plastic sandwich bags, or any other porous wrap are recommended as they allow the mezuzah to breathe. Saran Wrap holds moisture in, which may cause damage to the mezuzah.
A mezuzah case that does not necessitate the mezuzah to be rolled tightly is best. This will place less stress on the writing and help prevent the ink from cracking or crumbling. Also, when there is sufficient space inside there will be less chance of the mezuzah tearing or crumpling when it is put in and taken out.
The parchment used for mezuzos should not be thick, since this will be more difficult to roll. It may have to be rolled tightly to fit into a case, putting considerable pressure on the lettering and possibly causing ink to crumble or crack prematurely.
Stone cases are not recommended.
A mezuzah affixed outdoors must be placed in a sealed plastic, metal, or specially treated wood case which opens only from the bottom with a plug or screw. This will help prevent rain from seeping in. Care should be taken to prevent water from being directed toward the case from the bottom, for example with a sprinkler.
If a mezuzah will be in direct sunlight, use a solid white or silver-colored case in order to reflect the light. Clear plastic cases are not recommended for use in direct sunlight, as the mezuzah may get burn spots or dry out and crack. Dark-colored cases will get very hot and may damage the mezuzah.
Convenience in Affixing Mezuzos
Fragile Mezuzah cases, such as those made from silver, glass, ceramics and Polymer clay must be affixed with extreme care. If they are not affixed gently they may crack or break. Be sure not to tighten the screws or nails tightly as the pressure can also cause damage. It is advisable to use screws, rather than nails, to affix a mezuzah because it will be easier to take down later and there is less risk of causing damage to the case. In addition, the mezuzah case and the door frame can get damaged when removing nails.
Double-sided foam tape or a permanent bond glue may be used to affix a mezuzah case as long as the case does not have a removable back. This is an excellent option if you do not want to make holes in the door frame or will have difficulty making holes. Cellophane or masking tape should preferably not be used if the case will not be firmly affixed.
Many people dread removing and reaffixing their mezuzos and cases when it is time to have them checked. To avoid this feeling it is suggested to use cases which unscrew or unplug from the top or bottom. With these cases one only needs to remove the plug and possibly one screw to remove and reinsert the mezuzah.
If a mezuzah is stuck inside its case, carefully bang the case against another object to loosen it. Alternatively, you can remove the mezuzah by grasping the very bottom of it with a blunt tweezers, taking care not to damage the lettering. Before putting a mezuzah into its case, you may want to wrap thread around it (after it has been rolled and wrapped) and put it into the case with some dangling thread easily accessible. You can later remove the mezuzah by pulling the dangling thread. Save yourself time, effort, money, and grief by not forcing a mezuzah into its case.
In order to be certain that the Sha-dai remains facing forward inside an opaque case, the mezuzah should be rolled loosely enough so that it cannot rotate but tightly enough for it to be easily removed. Alternatively, it can be taped into place. If you use a clear case or one with a window for the Sha-dai, you will always be able to see if it is facing forward. Some mezuzah cases are made of a clear glass or plastic tube resting in a wood or metal base. The tube of this type of case often turns, causing the Sha-dai to shift. Simply twist it back into place as necessary.
Purchasing and Checking Mezuzos
It is in your best interest to purchase mezuzos well in advance, especially if the sofer you want to order from is in demand or you are ordering a large number of mezuzos. If you are buying from a retailer, place your order at least a few weeks in advance, and if you are buying directly from the sofer place your order at least a few months in advance. If you are moving to a new home, purchasing mezuzos in advance will give you one less thing to worry about as the move gets closer.
When having your mezuzos checked, it is a tremendous act of kindness to remove the mezuzos from their cases and protective wrappings before bringing them to the sofer. Otherwise, the sofer must spend precious time uncasing and unwrapping them. According to many poskim, the plastic wrapping must be put in genizah.
Label the side or bottom (not the back, where it will not be visible) of each mezuzah case with the date that the mezuzah was checked.
When taking down mezuzos for checking or painting, place each mezuzah in a separate bag and label each one with the room or doorway from which it was removed. This way each mezuzah will be returned to its proper place.
When taking down mezuzos for painting or renovations, be sure to put them in a safe place. When moving to a new home, be sure to put your mezuzos in a safe and accessible place so that you will be able to put them up without delay.
Protecting Mezuzos from Damage
If there is a possibility that paint, chemicals, or liquid will seep into the mezuzah case, the mezuzah must be removed prior to the application of the paint, chemical, or liquid to that area. If you are hiring painters, remove the mezuzos in the area yourself because the painter may paint over, lose, discard, or mistreat the mezuzah.
Do not use a spray cleaner or a wet rag to clean on or around an unsealed mezuzah case while the mezuzah is inside. Use a dry cloth instead. Also do not polish a silver mezuzah case while the mezuzah is inside.