Memories and treasures should last a lifetime and be passed on to future generations. Family activities like making a time capsule are a great way to share memories and help children learn some science.
What Is a Time Capsule?
A time capsule is a collection of objects put together to preserve the memory of a place, experience, or group of people at one point in time. People often make time capsules for special public occasions, and for others to open many years in the future. You can make one to celebrate a family event, to remind you of a special experience, or to remember friends, family, or school – or something else important to you.*
Time capsules are meant to preserve things over time, so this is an opportunity for some basic preservation science! All materials decay, but some deteriorate very, very slowly and others very fast. The amount and speed of damage depend on:
- chemicals that make up an object, and how they react with each other in the object;
- chemicals in items stored together;
- mechanical damage from folding, handling, pressure, abrasion, and other actions; and
- temperature, water, air, and light.
All of these work together to damage objects, whether they’re inside a time capsule, in your home, or in a library, archives, or museum collection. The good news is that the better you control these factors, the longer things will stay in good condition in your time capsule!
The first choice for your family time capsule is the container. It should keep out air and liquid, and be strong enough to protect the contents if it’s dropped or something is dropped on it. It should be made of a material that is chemically stable–slow to give off chemicals from its composition and slow to react with chemicals near it. The best reasonably priced container is an uncoated polyethylene (PET or PETE, recycle code 1) jar with a screw-top lid of the same material. You can also use uncoated high-density polyethylene (HDPE, code 2) or polypropylene (PP, code 5). These are available online or in container stores. Read the product label or ask what plastic was used to make the container. When the container is full and the lid is in place, carefully and gently turn the container upside down and have an adult very carefully drip wax from a candle around the edge of the lid where it meets the container, to seal it completely.
Consider More Chemistry
Choose pictures or other objects that will be fun to remind you of what things were like when you made the capsule. The more stable the chemistry of your items, the less damage they’re likely to experience over time. Clean, dry black-and-white photographs, items printed or written with archival ink on archival paper, undamaged metal or fabrics, and glass, stone, ceramic, or uncoated PET, HDPE, or PP plastics are the safest choices. Food, fresh plants, or any other living items are not! Computer media (discs, memory sticks, etc.) may be a poor choice, too. Even if they don’t suffer damage over time, if you open your time capsule 10 or 20 years in the future, the computer device you need to read the file may no longer be available. Remember to include a list of all of the contents and what they mean to you. The following Web sites provide detailed information about good and bad choices for your time capsule contents:
It’s All about the Chemistry
Since you probably won’t know the chemistry of all of your objects, or how they might react with each other, it’s important to isolate them – to package each object, or at least each group of the same kind of object, separately inside your time capsule. Packaging materials are as important as the time capsule itself or its objects. Put each item or group of like items in archival-quality paper (which may be buffered to slow the creation of acids) envelopes, folders, or boxes; uncoated PET zipper bags; or glass or stable plastic vials with screw-top lids. All are available in craft stores.
Preventing Mechanical Damage
Most objects are easily damaged if they rattle around with other items. Enclosures will help prevent this damage, but think about weight and movement. Fill the time capsule with the strongest, heaviest objects first, working up to the lightest and most delicate. If your capsule will include folded or fragile items, protect them from the weight of other objects by putting them in boxes, or putting them in the top layer of the capsule and thoroughly padding them to protect them from heavier items. If the time capsule is not completely full, you can use crumpled archival tissue to pad between layers and to fill the top space. Store the capsule upright, and handle it gently.
This includes moisture, air, temperature, and light. All of these factors contribute either additional chemicals, or energy to speed the reactions that cause damage, so it’s important to protect your time capsule from them. This is the reason to seal the lid with wax – to keep these agents out of your capsule. Many time capsules are buried, and as long as your container is air and moisture tight, you can bury it (assuming you have a place to do so, and you remember where it is!). It’s probably safer to put your capsule in the coolest, driest place available in your home. The upper shelf of a closet in an interior room, where you won’t be reminded it’s there, is a good choice. Put a reminder of the location of the time capsule somewhere to help you remember to open it in the future. If you store your capsule where it will be exposed to light, make sure to wrap it in a protective enclosure – a box or thick pillowcase would be a good choice
All of these guidelines may not be practical for your individual situation, but that the more of them you follow, the greater the likelihood that your time capsule will protect your memory treasures until you’re ready to look at them again. Here are some additional Web resources for time capsules and preserving family treasures that may interest you:
*These guidelines are provided for family learning and entertainment only. While they introduce important preservation concepts, they will not result in a professional or organizational time capsule intended to survive for more than a few years–the complexities of long-term preservation take more space than we have here. If a long-term time capsule is your goal, please see the Web sites recommended, and their information sources.