Oxygen Absorbers & Desiccant for Time Capsules: Handy Chart

Ageless Oxygen Absorber Packets (upon opening)

Oxygen Absorbers & Desiccant

Conditioning Agents

Finally we have a chart that designates a certain amount of oxygen absorbers for each of our time capsules. It does not go by total time capsule volume (cu. in.), but rather is figured on the head space of a time capsule that's considered to be 3/4 full by height. The last number given in our time capsule dimensions is always the height in inches (L x W x H).

Desiccant Packets make it easy to keep your time capsule items dry during storage.

As always, a disclaimer: you may need more than so designated if your time capsule is less than 3/4 full of items. If you have more than that shown or calculated, it's not considered a problem.

In practicality, when we cannot give you the exact amount below, we round up - so that for 2900 cc you will likely get 3000 cc. It's a factor of what we have in stock at the time we fill your order. When we package the absorbers in the special Marvelseal® MVP bags, extracting the air, we try to make them in the amounts sold separately (e.g., 2 packs of 300, 3 - 300, 2 - 500, 2 - 1000 and so on). The packs are clearly marked, and - a bonus - you get the formula for calculating them on your own included with the info leaflet attached to the packets. This updated chart shows the desiccant that we calculate, too - although you'll want to revise that depending on your contents and cushioning materials. If you have a lot of paper, you may need more desiccant in your time capsule. As a general rule, add 1 unit of extra desiccant to your capsule for each pound of paper you have to go inside.

The following amounts have been updated and are current as of Nov 2015. In most cases we have increased the amounts given for both Oxygen Absorbers and Desiccant. Number in parentheses indicates the amount normally given to customers for that size.

TC Size (inches)		02 Abs calculated/provided to you with time capsule order (in cc)		Desiccant (units)
5.5 x 22		600/1000		1/2 u
6 x 24		800/1000		1/2 u
9 x 4 x 12		500/1000		1 u
9x 6 x 15		700/1000		2 u
8x 6 x 20		900/1000		3 u
10x 8 x18		1300/2000		4 u
12x 9 x12		1000/1000		3 u
12x12x12		1500/2000		4 u
12x12x14		1800/2000		5 u
12x12x16		2000/2000		5 u
12x12x18		2300/2500		7 u
12x12x20		2500/3000		9 u
12x12x24		3000/3000		9 u
12x12x30		3800/4000		11 u
14x10x18		2200/3000		12 u
14x14x14		2400/2500		9 u
14x14x20		3400/3500		10 u
14x14x24		4000/4000		11 u
14x14x30		5000/5000		12 u
15x6x15		1200/1500		4 u
16x16x16		3600/4000		10 u
16x16x20		4500/4500		11 u
16x16x24		5300/5500		13 u
16x16x28		6200/6500		14 u
16x16x30		6700/7000		15 u

© 2013 Janet Reinhold
Updated 2015, February 2018

Updated 2021, May 14, 2021

Artwork Requirements for Plaques & Engraving

Plaque castings feature poured metal and graphics need to allow plenty of spacing.

Artwork Requirements for Engraving & Cast Plaques

Lately we have been inundated by customers and prospective customers who just don't 'get it' when it comes to artwork requirements for plaques and engraving. In particular, cast metal plaques are widely misunderstood. As one designer put it:

In general, it's not that people are unintelligent, but rather, they're ignorant about the process of making plaques.

But you don't have to have a degree in Graphic Arts to understand the requirements. Over the years I've learned that just because what you want on a plaque fits nicely when printed onto the same size paper, it doesn't mean it will fit on a cast plaque. Specific requirements for artwork, logos, and special fonts that we state on our website and brochures:

• Format must be in editable vector format (for example, *.ai (Adobe Illustrator up to CS5); *.cdr (CorelDraw up to X5); EPS files (*.eps) are acceptable but in vector format only.
• All fonts must be converted to curves or outlined
• All files must be in black & white only, no halftones or screens.

Those are our basic requirements, and it's for those logos your company may have that you want rendered onto a plaque or engraved onto the time capsule lid.

What do you mean by 'vector' graphics?

 Definitions of vector are full of what it actually is, and that's good. For instance, Wikipedia says:

Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon(s), which are all based on mathematical expressions, to represent images in computer graphics.

But just understand that it's different. It's not the same as that JPG file of your logo.

So why do you have the JPG handy and not the vector? Because the computer you use may not have the right programs to view it. Again, from Wikipedia:

Engraved Laser Marking for Time Capsule Lid

Modern displays and printers are raster devices; vector formats have to be converted to raster format (bitmaps – pixel arrays) before they can be rendered (displayed or printed)....It is easy to convert from a vector file to a range of bitmap/raster file formats but it is much more difficult to go in the opposite direction, especially if subsequent editing of the vector picture is required. It might be an advantage to save an image created from a vector source file as a bitmap/raster format, because different systems have different (and incompatible) vector formats, and some might not support vector graphics at all. However, once a file is converted from the vector format, it is likely to be bigger, and it loses the advantage of scalability without loss of resolution. It will also no longer be possible to edit individual parts of the image as discrete objects.

In our own shop, only one of our computers has the programs necessary to render such graphics. It's probably the same in your company. If you're not a graphics person and/or don't work with such graphics on a daily basis, why have the programs on your system?

So you can see from this explanation that when our requirement is for vector graphics, it's because we need to re-size the image without loss of the resolution or crispness of the image. Your JPG may work great for printing or for web graphics, but for engraving or rendering onto a plaque, it just doesn't work. Look to the creator of the logo for the right stuff.

Special Requirements for Cast Plaques

To allow for pouring of metal into the plaque molds:

• Minimum castable letter height is 1/4" all CAPITALS, or 3/8" Caps/Lower Case. 
• Typesetting must allow for at least 1/16" white space between each letter
• Line stroke in letters and artwork can be no smaller than 1/16" or 4 pts thick.

The font you want to use is important. Some fonts are fancier than others so that the requirements of the cast plaque are more difficult to fulfill, and you may need to go to a larger plaque size.

You can just give us your wording and plaque size and let us work it up to see if it fits. You can have us find a font that's similar to the one you wish to use, too. 

Another option for keeping the size of your plaque small (and your budget too) is to opt for the etched plaque. The cheapest is zinc. You can see lots of plaques made in zinc today and they certainly rival the look of a real cast bronze plaque. HOWEVER they will not last as long and cannot be subjected to the elements like a cast bronze or aluminum can. So it's best to keep these etched plaques indoors. 

Sometimes it's true that "You can't have it both ways." 
Make it simple.

 

Cast Plaques & Time Capsule Placement

Placing Your Time Capsule and Plaque

Recently a customer ordered one of our Easy Packages (the ones that include time capsule, kits AND plaque, and he had a few questions:

1. Will you center and properly size and format the text that we want on the piece?
2. What is the best mounting system if we want to mount on a piece of concrete that is embedded in the turf/soil.
3. Additional advice to achieve successful preservation for 50 years underground in Minnesota where the temperature and humidity varies significantly?

• Proof. For the plaque, we certainly will center and format the text that you send us. We send you a proof and specs sheet for you to sign off on and then we submit it to the foundry. That process usually takes about 4 weeks. Since you sent us the wording for your plaque, we are working on that proof for you now and you should receive it by email within 2 days. If you like certain fonts, let us know - quite often we have something similar on our equipment. It’s important to talk about the mounting method now, since if rosettes are needed, they can be planned for ahead of time.
  Usually, with a mounting as you describe, the mounting is a blind mount from behind and no rosettes or holes are seen from the front.
• Mounting. There’s a good example of that process on our website under ‘ceremonies’ in our gallery. We took some photos of one of our plaques being installed in Hollywood. Here is the link to the WAMU Hollywood Ceremony and their Installation of the new Hollywood Time Capsule and Plaque. With this type of plaque you get (usually 4) long screws that go in from behind. You can cut the screws to the length you want. In this way it is anchored to the concrete as it's setting up.
• Time Capsule Placement. I do recommend that you seal the area above the time capsule well (see the example below). Doing it in the way shown, with a covering and freshly poured concrete will help seal it from above ground environment. Once it’s buried, though, the temperature should remain stable unless it’s very close to ground level or if you have permafrost. Should you choose to use an enclosure of some kind, be sure it allows for any water to go through and not be held to the time capsule in any way. Do NOT wrap the capsule in plastic - please!  Don’t do anything to the time capsule that holds water to it. In the case of the 4200 Capped Cornerstone Time Capsule, place the time capsule so that the cap is on the top. In the gallery example, they are using a different style time capsule than the one you ordered (they had the Bolted 3000).

Example of a Time capsule Enclosure - this one's in a sidewalk. If you choose an enclosure, be sure it allows for drainage of normal precipitation coming in from above. If you are below sea level, other precautions must be planned.

You never want to pour concrete over the bare time capsule! Here a sheet of plywood is placed over the shoulders of the enclosure and seated before the pouring.

Before this pouring, the men applied removable red tape to the plaque and inserted the mounting hardware from behind. The screws are long - 4" - but can be cut to desired length.

Inserting the plaque into the prepared concrete surface.

Making sure the plaque is straight.

Making sure the plaque is level.

(c) 2013 Janet Reinhold. No liability is assumed with the recommendations given in this blog or on our main site at www.futurepkg.com. Updated to reflect new URLs from our new site 2015.

Burying the FPP Capped Stainless Steel Time Capsule

Burying Your Stainless Steel Time Capsule

Periodically, I receive questions from customers and would like to share those and the answers I give them. If anyone can add to the ideas, please post them here for all to benefit.

We are interested in buying a time capsule, probably one of the Burying Your Capped Stainless Steel Time Capsule. I read the description, and it said it is 'not intended for burial without protection and due diligence.' What does this mean? Can you provide us with kits to protect it in the ground, or instruct us on whom to contact.
                Thanks, -SW

Hi Mr. W,

We did not design it to be buried, but sometimes our customers do just that. Here are several ideas:

1. I hope you follow common sense procedures (for instance, don’t bury it where it’s watered regularly – such as a garden or under grass). See more on our Tips Page
2. We now include the 'wax sealant' kit 82042 for all of our capped cornerstone models. This will have instructions as well as the wax. 
3. Place the time capsule with its cap on the top (don't lay it on its side).
4. Seal the area above the capsule well. One option is to use a poured cement-over-plywood-base – see our Gallery, under the Ceremonies, and see the plaque installation towards the end of ‘Washington Mutual – Hollywood’. FPP The New Hollywood Time Capsule Placement.
5. Whatever you do, don’t put it into a vault that HOLDS water to the time capsule, or wrap it in plastic because of the same problem. Eventually, if even a stainless steel time capsule is sitting in water, it will corrode. We still feel this is the best material for time capsules (304+) due to the longevity and sturdiness as well as how inert it is.

Here, Rancho Bernardo chose to bury their Capped Cornerstone Time Capsule.

How Do Our Time Capsules Meet Your Conditions?

How Do Our Time Capsules Meet Your Conditions?

Whether you're in a hurry or on a strict budget, we probably have a time capsule for you. Consider our time capsule boxes as well as the affordable time capsule cylinders.

FPP Capped Stainless Steel Time Capsule

How Large is Your Project?

Small

Good choices for small budgets & projects include our cylinders.

Medium

Good choices for medium budgets & projects include cornerstone capped time capsules and smaller bolted models. 

Large

Good choices for large projects & budgets include bolted time capsules and many easy packages that include not only time capsule, but preservation kit and outdoor quality cast plaque, too.

And the Award Goes To:

Although not the same as Academy Awards, we've 'awarded' our capsules accordingly as follows:

Easiest to Use

1.    Bolted 3000 series
2.    Cylinder Time Capsules Mr. Future 08624 (08628) & Mrs. Future 08652 (08658)
3.    Capped Cornerstone 4200
4.    Cylinder Time Capsules  77590 Arnold Personal Time Capsule & 35120 Sally Personal Time Capsule

Most Affordable

1.    Clearance Cylinder Time Capsules "Seconds" or Refurbished Units (all new)
2.    Cylinder Time Capsules Mr. Future 08624 & Mrs. Future 08652
3.    Cylinder Time Capsules  77590 & 35120
4.    Capped Cornerstone 4200

Best for Outdoors Underground

1.    Bolted 3000 Time Capsules
2.    Capped Cornerstone 4200 can be buried using common sense placement guidelines
3.    Cylinder Time Capsules Mr. Future 08624 & Mrs. Future 08652 
4.    Clearance Cylinder Time Capsules "Seconds" are okay for burial, too.

Best for Indoors

1.    Cylinder Time Capsules Mr. Future 08624 & Mrs. Future 08652
2.    Cylinder Time Capsules 77590 & 35120, 35121
3.    Capped Cornerstone Time Capsule 4200

Most Easily Reusable

1.    Bolted 3000 Time Capsules
2.    Capped Cornerstone Time Capsules 4200
3.    Cylinder Time Capsules Mr. Future 08624 & Mrs. Future 08652 if sealant guidelines are followed properly

Lead Time for Making Your Time Capsule

1.    Capped Cornerstone Time Capsule 4200 (takes 3-4 weeks if not in stock)
2.    Bolted 3000 Time Capsule (takes 3-4 weeks if not in stock)

Longest Lasting Time Capsules

1.    Bolted 3000 Time Capsule - 100+ years
2.    Capped Cornerstone Time Capsule 4200 – 75+ years
3.    Cylinder Time Capsules Mr. Future 08624 & Mrs. Future 08652 – 50+ years
4.    Cylinder Time Capsules  77590 & 35120 – 25+ years

Choosing a Time Capsule Supplier

Why Choose Future Packaging & Preservation?

Who We Are

Future Packaging & Preservation is a small, experienced company that cares about quality, integrity, and honesty. Yes we have ethics.

We have provided time capsules to customers for over 25 years.

Future Packaging and Preservation: We're family owned and operated. We take a personal interest in each time capsule we sell. Even our employees are like family.

Our shipping person is also a retired quality aerospace engineer who inspects all items and they must meet 12 points of stringent quality standards before shipping to you. Sometimes we think he's too picky, but while we've had him, there's been no complaints about our quality (or our packing)!

Our Service

Our time capsules come with complete instructions, and you can call or email us directly for more info.
Each of our time capsule boxes (the bolted model and the capped cornerstone model) includes a limited warranty that covers workmanship, materials and more.
We listen to your comments and suggestions, and that's one reason we have  different kinds of time capsules. It's also why our preservation kits have changed over the years.

Time Capsule Materials and Designs 

Material

We use 304 stainless steel material for all the time capsules we make. Stainless steel makes a better time capsule than other materials. Aluminum is too soft. PVC and plastic material changes over time and becomes too brittle. Some of our competitors sell time capsules made of composite materials? Exactly what materials are in the composite?

Sealing

A note about bolted time capsules: If you choose any other time capsule that’s bolted, be sure to pay attention to how the other company's time capsule closes. Ours are painstakingly made with attention paid to details – including BLIND bolt holes that do not open into the capsule’s interior. To our knowledge, none of our competitors’ bolted capsules is designed in this way.

Questions to ask:

How does it seal? If the capsule has an O-ring or gasket, is it flat or round? Does the O-ring go into a machined groove specifically designed to fit it? What’s the material of the O-ring? We use silicone because it has the best aging properties and is inert. Do not use a time capsule that has a foam gasket or a plain rubber or 'butyl' gasket. That's where your time capsule will leak first.

Preservation Kits Assure Protection of Time Capsule Items Inside

We have developed our preservation enclosure kits using a variety of archival materials that should meet your needs in a sound, archival closed case storage environment. We purchase our supplies from archival suppliers. Be careful of materials you may purchase from suppliers that say 'acid free' but which are not and have not been tested. We know what conservation quality means. Enclosures that you use for photos should be safe and do no harm - the materials should have passed the PAT test for photo activity.

Compare Apples with Apples

Please compare apples with apples - in other words, compare stainless steel boxes with stainless steel boxes, not stainless steel boxes with aluminum boxes or cylinders and not stainless steel cylinders with PVC or composite cylinders. They are different materials and yes, you get what you pay for.

In the same vein, compare the marking methods fairly as to the materials used. Aluminum is a soft metal and it is cheaper to mark than stainless steel is.  Fancy sticky labels are just that - labels. They won't last very long after aging.

We have tried to keep our costs reasonable without loss of quality.

Choose Polishing (or not)

We asked, "What does polishing do to the longevity of a time capsule?" The answer was simply, "Nothing." Yet everyone knows that a polished piece is nice looking, so we offer that as an option for our box time capsules. The cylinder capsules were made all at once and we had them polished all at once, too. But let's talk about cosmetics. Cosmetics don't mean a lot in the long run when you bury a time capsule. What you want and need is a quality time capsule made well enough to protect the important stuff - your contents - over time. Polished time capsules are nice, but polishing does nothing to protect the metal over time. Polished time capsules are beautiful, and make a nice display time capsule. Add the option to your order for any of our time capsule boxes.

If cosmetics are important to you, choose to have us give your time capsule box a "mirror polish." It's beautiful. Ask for a quotation. But if you simply want a high quality container that will protect your contents and serve as a protective time capsule over time, you don't need the polishing option. All welds are shined, and the material we use for making the boxes is a satin polish finish.

These are just a few of the reasons we think you should choose our company. Thank you for considering us!

How to Choose a Time Capsule

How do I choose a time capsule container?

Over our 25+ years of service, we have had several styles of time capsules - not just one or two. That's because we serve different customers with different needs. Each style has unique advantages and disadvantages. Thinking first in terms of shape - it's either a cylinder or tube style or it's a time capsule box. We offer 4 sizes of cylinders or time capsule tubes, 18 sizes of the capped time capsule boxes, and 13 sizes of bolted time capsule boxes.

How you choose a time capsule depends on your needs.

• Placement. Decide what you want to do with the time capsule. Will it be buried, and if so, for how long? Maybe you just wish to display it, or store it in an archives or library. Sometimes time capsules are placed under monuments and inside of the foundation (or cornerstone) of a building.
• Length of storage. How long do you want the time capsule to lie undisturbed before it's opened up again?
• Size. The best way to figure a size is to have your time capsule contents already, put them in a container, and buy one that is close to that size.
• Budget. Do you have enough money? Don't skimp or gamble on a cheap container. You can opt for a less expensive container that assures your items will survive their intended life of interment. 

Cylinder Time Capsule Containers: "Future Line"

Are you on a tight budget? The cylindrical Future Line Time Capsule may be the most practical choice. Always in stock, these capsules are made of stainless steel, are pre-polished, pre-marked on the bottom with the phrase “Time Capsule.” Should you wish an even deeper discount, consider a standard or 'irregular' version. All of these time capsules may be buried, but follow the instructions included with the sealant kit carefully.

Our cylinder time capsules are available in the following sizes, listed by diameter and length (figure outer dimensions) from the largest to the smallest:

Time Capsule Cylinders

Size	Name	Basic	Bundle
6” x 24”	Mr. Future Time Capsule	08624	08628
5.5” x 22”	Mrs. Future Time Capsule	08652	08658
7.75” x 9”	Arnold Time Capsule	77590	77598
3.5”x11.75”	Sally Time Capsule	35120sd	35128sd

• Basic Cylindrical Future Line Family Time Capsules come with label, desiccant or silica gel, and small sealant wax kit. 
• Bundles come with label, desiccant or gel, and sealant kit - but also have preservation kit for all, plus oxygen absorbers for all except Sally.
• Easy Packages include the Bundle plus an outdoor quality plaque.
• Optional: Add simple light engraving or laser marked engraving of the lid.

Box Time Capsules

If you need more space than those time capsules afford, or if you have a lot of items that need to be stored flat, consider our box shaped time capsules.

Bolted Time Capsules

The Bolted Time Capsule comes with a closure kit (O-ring, bolts, washers, oxygen absorbers, and desiccant, a warranty,  a manual, and other information). Will you bury the time capsule over 75 years? If so, consider the Bolted Style 3000, the best designed time capsule available. Safe for burial of up to 100 years or more, this time capsule needs no vault enclosure and it is simple for you to close securely. We regularly order 13 sizes of this style time capsule box. Please see our online store or give us a call to see if your size is in stock.

Simple Capped Cornerstone Time Capsules

If you need a cornerstone time capsule, consider the Simple Capped Style 4200. The Simple Capped Time Capsules have attached cap and body, so they come with a sealant kit as well as oxygen absorbers and desiccant, a warranty, and other information. When placed inside of a building or semi-protected area, this capsule may be all you need, and the estimated life of this capsule’s seal is about 75 years (or more). This box time capsule is reasonably priced and has been buried successfully for limited periods. It's easy for you to set up, make presentations with, and seal up when everything's over. We regularly order 18 different sizes of this time capsule box, so see our online store today for availability and pricing (or give us a call).

Options

Time Capsule Finishes

The box time capsules have the 2B natural finish, and that is how we price them. 
As an option, we can polish your time capsule. Polishing makes the capsule an art piece and is strikingly beautiful. This option is popular for time capsules that are to be displayed.

Laser Engraving

Mark the lid of your time capsule with a beautiful engraving.

Preservation Enclosure Kits

Preservation kits are available, too, so that you can use the same fine enclosures for your items that museums do for storage of their items. Our customers often buy one of our smaller kits and supplement it with our archival supplies as needed. Popular additions include extra Permalife Paper (for printing, copying, wrapping, making stationery). The contents of our preservation kits have changed over time, but you can always check the exact contents in our catalog and also on the online item's description. We have contacted our customers over the years to see which items in the kits they used and which they did not, as well as to see if they needed any items not in the kit.

Plaques Mark the Spot

Mark the spot of time capsule container placement with a Cast Metal Plaque. Choose either a bronze cast plaque or an aluminum cast plaque. Both are outdoor quality.

For updated pricing and information, see the catalogs on our web site and our online store (futurepkg.com).

Controlling Humidity in a Time Capsule

Your Time Capsule's Inside Environment

Common Questions...

We are often asked how we calculate the How Much Silica Gel Do I Use in My Time Capsule? included in each of our time capsules and packages. What do we mean by 'conditioners'? They are the packets of drying-out agents (desiccant, Silica Gel Packets) and oxygen-eating agents (Ageless Oxygen Absorbers) that help to condition the air in a closed time capsule over time. Common questions are also asked when considering a museum’s environment for an exhibit case, but the first 4 might be done away with if you have a proper time capsule container. It gives us a starting point of discussion.

4 We Don't Care About:

    1. What is the difference in RH between the enclosure and the room?

    2. What is the permeability and air leakage of the enclosure?

    3. What is the stability of the overall room temperature?

    4. What is the desired maintenance cycle?

Desiccant and silica gel control moisture inside the container.

Just forget about these things for time capsule environment purposes. We're not too concerned about these 4 because a time capsule is not an exhibit case. A time capsule is special. It is a well sealed airtight rigid container. Assuming customers follow our guidelines about not subjecting it to changes in temperature (i.e., don't place it outdoors above ground) and how it seals (don't use a FOAM or plain rubber gasket, e.g.), they don’t need to worry too much about changing the desiccant. In a museum’s exhibit case, the conditioners need to be frequently changed. But in a time capsule, you leave it alone – static conditioning is okay so long as the time capsule and its surrounding environment are stable. Consider these others, however.

What We DO Care About:

 5. How vulnerable is the item to humidity (or the lack of it)?

We all know what can happen to paper as it takes on moisture – fungi, mold, foxing.

But what about too much dryness? At one time I worried, “Are we making the environment too dry inside of our time capsule containers?” But studies done on papers and books indicated a 20% humidity worked as well if not better than 50-60%. All of our silica gel and desiccant products are provided at the 20% level. If you have something sensitive to dryness (i.e., leather), you could consider preconditioning it yourself or use the MVP bags inside of the dry time capsule.

Consider first the type of items you have and then consider what each needs.

6.  What is the volume of the enclosure?*

Consider two box examples, shown below. Time Capsule Box A measures 12x12x12” and has a cubic volume of 1728 cu. in. (12x12x12). Time Capsule Box B measures 12x12x24” and has twice that volume or 3456 cu. in. (12x12x24). It would follow that Time Capsule B will need more conditioning than Time Capsule A. However, what if Time Capsule A is almost empty, while Time Capsule B is almost full? Just how much control is needed? Does it matter what Time Capsule B is full of?

We don't show a cylinder example for this exercise, but we do show you how to calculate it below. It's apparent that the cylinder shape does not afford the same usable volume that the box shape does.

7.  How much relative humidity control is needed?

Let’s assume you don’t need to worry about the time capsule container (this is true if it's one of ours). It’s stainless steel and airtight and placed in an area that’s got stable temperature (no changes). That’s a big assumption, but an important one, because it allows us not to worry about the things museums do – constant changes in relative humidity and temperature from the room the artifacts are housed in and the building, too. Not even the Crypt of Civilization is intended to be walked in and out of frequently.

So, the amount of humidity control you need in a time capsule is dependent not only upon the items placed inside but also the air space left over after items are inside. You could have a lot of paper (paper contains moisture) or you could have a lot of plastics and toys and such (not much moisture). It follows that you will want to use more desiccant in the capsule if it has more paper than artifacts inside. Air space inside will have oxygen and moisture in it, too – it’s not really empty. So you'll want to allow for that.

Rule of Thumb for Time Capsule Desiccants

Here is a rule of thumb chart that is used for any rigid container such as our time capsules. The amount you end up using will depend on the items’ characteristics. Mostly paper contents? Use extra desiccant.

Know Your Volume

First, determine the volume of your capsule.

Box Shapes

For a box, it's easy. Just take Length times Width times Height (LWH).

A box that measures 12" x 12" x 24" gives you 3456 cubic inches. One that's 12" x 12" x 12" is 1728 cu. in.

Cylinder Shapes

If you wish to see how a cylinder compares to a box in volume, let's use a cylinder that measures 12" in diameter and 24" in height.

First, you need the basic formula, a bit more complicated than the box's:

PI x Radius x Radius x Height, or πr2h

Now plug in the numbers.

    For Pi, let's use 3.14159.
    Since the radius is half of the diameter, our radius value is 6" (half of 12").
    Measure the height (24").


It's easy to see that you get less volume in a cylinder of 12” d x 24” (3.14159 x 6 x 6 x 24" = 2714 cu. in.) when compared with a box of 12 x 12 x 24” (12 x 12 x 24" = 3456 cu. in.).


The chart below shows a comparison of time capsule volume and the amount of desiccant or silica gel commonly recommended for it - which you can increase according to the amount of moisture content. 

Simple Manufacturer’s Chart for Desiccant/Silica Gel

Simple Manufacturer’s Chart for Desiccant/Silica Gel  (by Container Volume)
Time Capsule Volume (Cubic Inches)	Units Desiccant (Empty Capsule)	Grams Silica Gel (Empty Capsule)
237-475	1/6	2
476-714	1/3	4
715-1428	½	6
1429-2856	1	12
2857-4285	2	24
4286-5713	3	36
5714-7142	4	48
7143-8570	5	60

Know your Time Capsule Contents

No one places an empty time capsule. You'll have items inside. Now let's consider some items and how you adjust for them.

Adjusting for Paper Content

How much of your time capsule contents are paper? Think of a ream of paper. You might have a City Budget that's about half that size. If a ream of paper weighs 5 lbs, then your budget would be about 2.5 lbs. So the rule of thumb for paper items (the most moisture laden materials) is this:

Add 1/2 Unit of Desiccant for each 100 sheets of paper (or each pound of the paper product's total weight). Taking 2.5 times 1/2 u. = about 1 and 1/2 U desiccant for that one item.

If using silica gel, add at least 10 grams extra for each 100 sheets or 1 lb. The weight of your paper may vary, but in general, figure 500 sheets of basic 20#wt paper (a 'ream') weighs about 5 lbs. Silica gel is best used for smaller container sizes such as our cylindrical family style time capsules or smaller. Desiccant works just as well as silica gel for time capsule purposes, and you won't need as much.

Adjusting for Oxygen Absorbers

If you use Oxygen Absorbers, you may need a bit more. In addition to what you need above, use this rule of thumb:

Use at least 10 g of silica gel or 1/2 unit of desiccant to every 1000 cc oxygen absorber in your time capsule.

Figuring how many oxygen absorbers you need to begin with is a different process and I will cover that in another article.

A Tale of 2 Time Capsules

Here's a comparison of two stainless steel time capsule boxes:

Time Capsule Box A	Time Capsule Box B
12" x 12" x 12"	12" x 12" x 24"
Volume: 1728 cu in.	Volume: 3456 cu in
Model: 42172 Ganymede	Model: 42350 Neptune
Contents: Just a few paper items	Contents: About ½ full of paper items  (4 Reams or 2000 paper sheets or 20 lbs)

And here's how you might calculate the desiccants needed for each:

Total Suggested Using Chart plus Adjustments for Paper, Ageless
Time Capsule Box A	Time Capsule Box B
Empty: 1-1/2 Units	Empty: 2-1/2 Units
Paper: N/A	Paper: 20 lbs est., Add: 10 Units
2,000 cc Ageless: Add 1 Unit	3,000 cc Ageless: Add 3 Units
Total for Ganymede: 2-1/2 Units	Total for Neptune: 15-1/2 Units

As you can see from the above chart for volume, the makers of  desiccant and silica gel have made the cubic inch recommendations conform to the size of packets they make. You will need to take the volume in cubic inches of your time capsule container and apply it to the above chart. For instance, 1728 falls in between 1429 and 2856 on the chart above. If you used estimated interpolation you might give empty Time Capsule A 1 ½ units rather than just 1, and empty Time Capsule B 2 ½ units rather than just 2.


We include desiccant conditioners with all of our time capsules, and in most cases, we give you plenty. If you get a Preservation Enclosures Kit, you get even more. Check out the contents listing for our large K3 time capsule preservation kit, for 56701 (the 1 unit pack), you'll see that it has 8 units. You can use the rules of thumb above to determine if you need more than we provide. There's no way for us to know what your contents are made of in advance, so it's good for you to know some common sense ways to figure a good amount for your own project.

Supplement it by adding more Desiccant or Silica Gel from our online store. Like the Oxygen Absorbers, they are quite inexpensive for all the good they do! You can order more desiccant products from us directly in the following amounts:

56610. 10 gram Silica Gel.

56700. 1/2 Unit DesiPak.

56701. 1 Unit DesiPak.

56702. 2 Unit DesiPak.


I realize this is a lot of information to just throw at you, so if you have any problems with your calculations please give us a call or email - and please visit us at Future Packaging & Preservation.

(c) 2013 Janet Reinhold. Updated to reflect our new site on 9/1/2016; updated again 2/20/2018

No liability is assumed with respect to the advice given here.

Not So SILLY: Silica vs Silicone

Silica and Silicone sound alike!

5 Gram Silica Gel Packets - they dry the air.

The other day I got a call from a young woman who wanted to buy a time capsule from us - one of our cylinder styles in the Future Line time capsule series. At the time, for the "Basic" configuration, we included just a label and either a silica gel or desiccant pack with it. It had no sealant. (Now we include a small sealant with Basic!)

"Do you need to bury it?" I asked. "If so, you'll need to add a silicone sealant kit. It's a few dollars more."

"Yes we are. What I need to know is if the silicone is included with the Basic."

"The Basic includes perhaps the silica gel, but not the silicone sealant," I said.

"What's the difference?"

Silica Gel Beads are what's in the Packets.

"Silica gel is a kind of desiccant that dries out the air inside a package, like the little white packets you might see in with a new pair of shoes. Silicone sealant comes in a tube and is like a caulking material - you squeeze it on using the instructions provided, and seal up the capsule for burying or long term placement without peeking."  

(We're located in California. It could be even more confusing if we were in the Silicon Valley instead of the San Gabriel Valley - home of the Tournament of Roses Parade, In-N-Out Burgers' History, Jet Propulsion Laboratory, and Big Bang Theory (the show)).

What is the technical difference?

Silicone sealant is a form of rubber that has excellent aging properties.

 

• Silicone rubber is an elastomer - a synthetic polymer - made up of silicone, which in turn is made from silicon, carbon, hydrogen & oxygen. It has the best aging properties of all rubbers, and we prefer it for time capsule sealant use. We sell it as a sealant in a tube of 4 oz or 1 oz amounts. It's easy to apply, is inert, non-corrosive and lasts a long time. Yet, unlike epoxy, it's removable when the time comes to open your time capsule. It also won't crack over time as epoxy and other sealants do. Does your time capsule supplier use silicone rubber gaskets? Ask them. We use a formed silicone rubber gasket or O-ring that fits into a machined groove on our Model 3000 time capsule. Other rubbers simply don't last as long.
• Silicon is an element (Si, 14). It's the 8th most common element in the universe by mass, but you won't find it as a pure free element. You see it distributed in dusts, sands, planetoids & planets as various forms of silicon dioxide (silica) or silicates. It's also used in certain forms for semi-conductors and other sensitive electrical components, hence the Silicon Valley names.
• Silica or Silicon Dioxide is an oxide of silicon with SiO2 as its formula. It's made into many forms, and one is silica gel.
• Silica Gel is most commonly seen in the form of beads inside of a small white packet. In this form, it is used as a desiccant to control local humidity that in turn avoids degradation of goods in storage. 
• Desiccants are a hygroscopic substances that induce or sustain a state of dryness (desiccation) in its local vicinity in a moderately well-sealed container. That's good for time capsules! Because of their common use in preservation, it is recommended that the desiccant used be chemically stable or chemically inert, and a number of useful desiccants with this property have been identified and are in common use, such as silica gel and clay-based desiccants. 

We sell the SILICA GEL in 10 gram silica gel packets; we sell the desiccants in 1/2 unit clay based desiccant, 1 unit clay based desiccant, and 2 unit clay based desiccant packs.

In another blog I will discuss how much silica gel or desiccant to use in your time capsule. Since paper contents have more moisture in them than plastic and metal contents, you will want to use more desiccant inside your time capsule than you might find in a chart for long term storage of machines, plastics, or shoes.

In the meantime, I hope this is a good explanation of the SILICA GEL vs SILICONE SEALANT confusion as to names.

Please visit our main website at Future Packaging and Preservation Time Capsules.