Often several individuals each want a portion of a loved one's cremains, which is what portion urns are for. Alternatively, part of the cremains are to be scattered and only a portion kept in an urn. Therefore, portion urns are smaller, and may be made in sets.
Keepsake urns or boxes are intended not so much for cremains as for mementos such as a lock of hair, a wedding ring, or small items of sentimental value.
Urns may be made with lids that lock or twist on, or the lid may be sealed with silicone glue. If you never intend to open the urn, it should probably be sealed, especially if it doesn't have a locking type of lid. If you may need to open it, such as to scatter the cremains at some later date, then one with a lid which can be secured so it can't be casually opened is a good idea. Many, though not all, of my urns are made with a lid which can be twisted to lock it on, though of course this isn't a permanent or air-tight seal.
Cremation is an increasingly popular option, both for economic and environmental reasons, and there are many options for dealing with the cremains of a loved one. Many people instruct their heirs to scatter or bury their cremains, but some heirs want to keep the cremains, or a portion of them, close at hand in an honored spot in the home. Selecting an urn which reflects the personality and tastes of a departed loved one can be a valuable part of the grieving process, helping the bereaved to remember the life of their loved one and feel closer to that person's spirit.
I make urns because I want to expand the options available to grieving heirs. While the urns available at most funeral homes are often beautiful and highly functional, they are mass-produced and may feel somewhat impersonal compared to a one-of-a-kind handmade urn. If my urns can help in the process of grief and healing, they have done their job. And occasionally someone finds an urn she really loves and buys it for her own final resting place, thus emphatically indicating her intentions to her heirs and saving them that potentially difficult task.
There are a lot of answers to this question. I could say, because I'm at an age where I start to think about such things more. Or I could say because there is a market for them, which is another way of saying people seem to want and need hand-made urns. In my three decades of pottery-making I have made quite a few urns; some on commission, sometimes selling what I thought was a cookie jar to someone who wanted it for an urn, and sometimes making a lid for a piece which started life as a vase. After a couple of decades of this, I started trying to figure out the elements of a really good urn.
First of all, I wanted to design forms which were elegant and graceful, or round and generous, and didn't look like a cookie jar. I also had to get the size right, though of course there is a need for larger and smaller urns, and sometimes people want to divide up the cremains of a loved one among several family members, or only keep a portion and scatter the rest, so I wanted to make a variety of sizes.
Then, I needed to get the lid right. I wanted a lid which fits closely, isn't likely to fall off and doesn't invite the casual looker to lift it up. Some people seal the lid with silicone glue, but I wanted to design a locking lid so the urn can be opened if necessary, for instance, if you want to scatter the cremains or divide them at some time in the future. So, I came up with several different styles of lid, some which lock on, some which might have to be sealed. I paid particular attention to the knobs, trying to avoid the standard, practical round cookie jar knob. I thought of the knob as a focal point or a finial, a finishing touch. As the highest point on the urn I wanted each knob to make a statement. So some are like a church steeple, others like a fan, a hat, or a crown.
But these are purely mechanical issues. The real question was how to finish and fire each pot. Clay is such an appropriate medium to contain the remains of a life; we speak metaphorically about "mortal clay" and refer to the body as a vessel for the soul. We even name the parts of a pot after the human body, so a vase has a foot, a belly, a shoulder, neck, and lip. And as a potter, I think of a pot's journey through fire as a metaphor for the journey of life. So I chose to use every firing method I could, trying to design forms appropriate for each firing technique. On some of the pots I decided to use multiple glazes, layered like a landscape. Others are fired with crystalline glazes, which are very beautiful but very finicky and need to "soak" at a high temperature to allow the crystals to develop. Others are wood-fired, in which the pots are marked by the ashes and flame passing through the kiln, as a person is marked by his life's experiences. Another favorite firing technique, which definitely yields one-of-a-kind results, is pit-firing, in which blank white unglazed pots are nestled in wood shavings, surrounded by copper, salt, seaweed, and other materials, covered with wood, then fired. The fire marks these pots with warm shades of red and yellow and rich black, giving each pot its own life story.
Horsehair firing is another very special technique, in which hairs are laid onto a hot pot and leave their mark as they burn. I have made many memorial pots for beloved horses this way, though not too many urns, which could get very large! - and a few for dogs, cats, birds and even one for a person, a horse-lover who had commissioned several of my memorial horsehair pots. Each kind of hair leaves its own unique mark, literally burning a record of its presence and its passing into the surface of the pot.
Now I find people actually shopping for their own urn, buying pre-need, the way the funeral industry likes to sell burial plots, looking for the one which best expresses their own life's journey, saving their heirs from having to conducting the search at a difficult time. I imagine some of these urns might contain cookies until they are needed for their final purpose.