DIY Chronicles – Page 3 – Yet Another Unitarian Universalist

Pot-in-Pot Preservation Cooling System

This system, developed by Mohamed Bah Abba of Nigeria, cools food by evaporation, using no electricity. The Arabic term for this device is transliterated as “zeer,” so it is sometimes called a “zeer pot.”

How it works: The Pot-in-Pot Preservation Cooling System consists of two nested porous clay pots, with fine sand in between them, and a cloth covering the opening. You pour water into the sand, until it soaks through the outer pot. You also soak the cloth in water. As the water evaporates from the outer pot and the cloth, it cools the inside. The sand and pots act as both water reservoir, and thermal mass (so the pot stays cool when you open the lid). The moist interior is especially good for cooling fresh produce (which is what it was originally designed to do).

How cool it can get (theoretically): The inside temperature of the Pot-in-Pot Preservation Cooling System depends on outside air temperature, humidity, air flow around the pot, and whether the pot stands in the sun. Under ideal conditions, the inside temperature should get close to what meteorologists call “wet-bulb temperature.” Some users report temperatures as low as 40° F. I will track the temperature inside this pot over time.

How I made one:

Materials:
1 – 12″ dia. terracotta pot
1 – 14″ dia. terra cotta pot
6 – small pottery feet
2 – corks to fit the holes in the pots
1 – 12″ dia. pot saucer
1 – old T-shirt
25 lbs. of fine sand
water

Note that dimensions of terracotta pots are variable, so you may have to adjust things to fit what you can get.

Sand the holes in the pots until the corks fit smoothly inside. Cork the holes. Place 3 of the pottery feet in the bottom of the 14″ pot so that the 12″ pot will fit inside without the corks bumping. Then fill the rest of area with sand, leaving room for the cork in the 12″ pot. Now put the 12″ pot inside, and fill the space between the pots with sand with a funnel — I made a funnel from a cut-off seltzer water bottle — to within an inch of the top of the outer pot.

Place the whole assembly on the three remaining pottery feet, so air can circulate on the bottom, which will increase evaporation and cooling slightly.

Pour an inch or two of water into the 12″ pot, wetting in the inside of the pot. Next, slowly pour water into the sand, letting it soak in. The idea is to give the water time to soak into the sand and the terracotta pots. It can take several hours and up to a gallon of water to fully charge it. I found if I rushed this step, the inner pot started floating up; then I had to weight the inner pot with a cinder block to keep it in place until the water soaked in. Some people suggest tying the inner pot down with a strap or rope; others use threaded rod with nuts and washers (expensive and sure to rust). I had a cinder block on hand, and that worked fine.

The pot saucer isn’t entirely necessary, but it helps keep the inside clean, and where we live it helps keep the squirrels out of the food (the cinder block might even keep raccoons out). Pour some water into the saucer, soak the old T-shirt, and cover the pots with the T-shirt, adding even more evaporative surface. It gets pretty windy where we are, so I tied the T-shirt in place.

Total cost: about $55 (if you have to buy sand), with no cost to run it ever. Mohamed Bah Abba sells them for 40¢ ea. in Nigeria, a brilliant example of low-cost yet highly effective technology from the developing world.

More about this invention here.

Clay pot irrigation

Carol and I are experimenting with low-water irrigation systems for the garden. I’ve been using porous hose irrigation for years, purchasing porous hose made from recycled rubber tires, and burying the hose a few unches under the surface of the soil. David Bainbridge’s book Gardening with Less Water: Low-Cost, Low-Tech Techniques shows other highly efficient irrigation systems, including buried clay pots.

A buried clay pot is about as simple as an irrigation system can get: take a terracotta pot, put a cork in the hole in the bottom, bury it almost all the way in the soil, fill with water, then cover with a terracotta saucer.

In the photo above, we’ve buried a clay pot in the tire garden built by our congregation’s ecojustice class, and Carol is filling it with water. In the next photo, Carol is about to put a lid on the buried clay pot; you can see the cork down in the bottom of the pot.

Bainbridge suggests placing buried clay pots about every 24-36 inches in a standard garden. So we figure that one buried clay pot is probably enough for one tire garden. It will be interesting to see how often we have to fill the clay pot.

In our garden at home, we’re planning to try a somewhat more complicated version of this system: a porous terracotta capsule, fed by a hose. Until we get that to work, here’s a photo of the tire garden with the buried clay pot in the middle, and the squirrel-proof cage in place:

Experiment in hugelkultur

Carol has decided to experiment with hugelkultur in the garden this year. A hugelkultur garden bed consists of decaying wood and other compostable material from plants. This technique is supposed to create more fertility in the soil, and improve water retention. Given the ongoing drought here in northern California, improved water retention alone makes this technique worth trying.

Rather than build up a mound of decaying material, as is typical with hugelkultur, Carol got me to make a raised garden bed; with the tiny amount of space we have for our garden, this seemed to make the most sense. We got some cheap boards from a lumberyard, I scrounged some scrap wood for the corners, and in about an hour we put together a bed 96 inches long and 25 inches wide. Then we put in some partially finished compost, along with twigs and small branches.

hugelkultur raised garden bed

In the photo above, we’ve put down a layer of partially finished compost; the two buckets behind the raised garden bed are more compost waiting to go in. Carol has started laying some twigs and branches on the compost. After this, she put down another layer of compost, and then added a layer of potting soil we purchased from the hardware store across the street.

Carol is also planning to set up a greywater system (she is something of an expert on the topic). We already collect greywater — we have to run about two and a half gallons of water before the water in the shower gets hot, so we collect this and use it for watering the garden. Given how bad the drought is, that wasn’t enough water, so she is looking at other easily accessible sources of greywater that we can use without annoying our very nice landlord.

If you look closely at the photo, you’ll see potatoes growing in the raised bed behind the new bed. Today they started wilting a little. The National Weather Service predicts “dry weather and above average temperatures are likely to persist into the first half of next week”; we’re going to have to start watering the garden now, right in the middle of the winter-wet season. This is global climate weirdness happening in front of our eyes; maybe hugelkultur is one small way to help restore some balance to an out-of-balance world.

another view of hugelkultur bed

Above: The bed with more twigs and branches, and more bins of partially finished compost ready to go on top (photo credit: Carol Steinfeld).

Venison

Yes, yes, I know, once you saw a Disney movie in which a deer was killed and now you can’t eat venison. However, from an ecological standpoint, deer are a native species that fill an existing ecological niche, unlike the soybeans in your tofu which are invasive exotic species raised in monoculture fields that wipe out countless acres of habitat. And if you’re a small farmer, like Carol’s friend Eva, deer are an herbivore pest in a landscape that now lacks large carnivores to keep their population in check. So eating low-fat, free-range, non-GMO, antibiotic-free, organic venison that is untouched by American Agribusiness is actually an environmentally sound act that lets us humans fill the ecological niche of the large carnivores we have mostly extirpated from North America. It’s nice when we humans can play a positive role in the ecosystem, instead of just replacing the existing ecosystem with our own suburban and urban ecosystems.

When she stayed with us earlier this week, Eva gave use part of a haunch of venison. Carol stir-fried some chunks of venison with onions and greens; it looked really good, but I decided I wanted plain venison. I sliced it thin, and gently fried it in a little butter for a late brunch.

Venison cooking

After gently frying both sides, I covered the pan and let it steam for a minute until the meat was just well-done, with no red in the center. It was fabulous: lean, tender, and very tasty. I re-heated some of the “Warthog” wheat berries in the pan drippings, and the combination of the nutty wheat, the butter, and the meat drippings was the perfect addition to a satisfying brunch.

Wheat

Carol’s friend Eva, who is a farmer, stayed with us last night. When farmers check luggage on the plane, what do they bring in that luggage? Turnips, onions, garlic, frozen venison — and wheat berries. The wheat berries are a hard winter variety called “Warthog,” from friends of Eva’s who farm in Essex, Massachusetts. Eva soaked the berries in water overnight, and we cooked them in the rice cooker this morning. We added a bit of olive oil and a sprinkling of salt: the perfect breakfast.

Hard winter wheat, var. Warthog

Supercharging Altoids (R)

Back in 2006, when Wrigley bought out Altoids (R) brand mints, they replaced the peppermint oil with artificial flavor. Although they soon resumed using real peppermint oil, the mints have never been as strongly flavored as they once were. So here’s how to supercharge Altoids (R) so they taste as peppermint-y as they did prior to 2006:

Go to your local health food store, and get the peppermint spirits which are sold as a dietary supplement. I got “Herb Pharm” brand “Peppermint Spirits Essential Oil and Whole Leaf Extract”. Note that they have changed the label since I bought mine (a one ounce bottle lasts a long time), and the new label is different than the one you see in the photograph below. Now get a small dinner plate, and spread out the mints on it.

Supercharging Altoids (R)

1. A mint ready for supercharging.
2. Adding peppermint spirits; the typical mint will absorb about three drops.
3. After adding peppermint spirits to one side, let the mint dry out (this could take 15 minutes).
4. A mint flipped over waiting for peppermint spirits to be added to the other side.
5. A supercharged mint drying out and waiting to be eaten.

Once you add peppermint spirits to both sides, the mints are somewhat damp and fragile, and it’s best to let them dry overnight before putting them back in the tin.

(If you want to know more about artificial flavor in Altoids, I wrote about it back in 2006 here, here, and here.)

Easy face painting

Some of our high school youth youth advisors went to Kids Carnival today, the fun event organized by the University AME Zion Church as a way for people of different races and ethnicities to get to know each other a little better while having a good time. Our youth group offered to do a face painting booth. We lucked out in that Elaine, a high school senior from the Palo Alto Vineyard Church, joined us — she is a fine artist who has her own business doing face painting for kids’ birthday parties. We let her do all the hard designs (Ice Bear, a Death Eaters logo, etc.), and we used our own easy designs.

Our designs turned out to be easy enough that children can do them (we let some of the children who came to our booth use our paints to paint designs on each other) — yet they’re satisfying and look pretty good when you’re done. I’m posting them here in case you want to use them next time you do face painting in your congregation. Except where noted, our designs are meant to go on cheeks or backs of hands. We had copies of the designs where children could look at them and choose the one they wanted. One last suggestion: it is worth spending extra money for good face paints; we bought the cheap ones, but when Elaine let us try hers, we saw that they were far better.

Shoulder pole carrier for water

Every other year in our Sunday school, we do a recreation of a Judean Village in the year 29 C.E. Children become “apprentices” to artisans, and do activities that evoke village life in 29 C.E.

Carrying water by hand from the village well to wherever it was needed was an integral part of village life. This year, Edie Keating came up with an activity in which children learn how to use a traditional shoulder pole carrier to bring water to irrigate plants. Given the extreme drought that is blanketing most of California, this is also a very relevant activity. Ancient Judea had a very similar climate to ours — what if we had to carry all our water from a well by hand? — how would that change our water consumption habits?

I got to design a shoulder pole carrier using readily available materials. It was fun to design and build, and once it was built it was surprisingly comfortable and easy to use. This is a cool piece of ancient technology that really works well!

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Assembled materials

Materials for 6 pole carriers:
— 100′ of 7/32″ cotton “sash cord” or “all purpose clothesline” (easy to tie, and soft on kids’ hands if they grab it)
— 12 ea. 1-gallon plastic buckets, often sold as painter’s buckets; the ones we like best look like miniature 5-gallon buckets with sturdy reinforcement at the top (see photo above)
— 6 pcs. 5/8″ dia. 4-foot long hardwood dowels
— 9/16″ drill bit and drill (hand drills work well for this project)

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Measuring for the holes in the buckets

Step one:
Mark out locations for three holes spaced equally around the bucket. Our buckets were 7-3/4″ in diameter, and spacing the holes 6-3/4″ apart (as measured on a straight line, as in the photo above) provided fairly equal spacing.

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Drilling the holes in the buckets

Step two:
Drill three holes as shown in the photo above.

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How the cords are tied to the buckets

Step three:
Cut two lengths of sash cord, one 6′ long, and one 4’6″ long. Thread cord through holes and tie with two half hitches as shown — the longer piece of cord is tied at its two ends through two holes, and the shorter piece of cord is tied at one end through one hole. Note that two half hitches function as a slip knot, so snug the knot down to the bucket. (If you don’t know how to tie two half hitches, look at a Scout handbook, or search the Web for instructions.)

Make two of these assemblies, one for each end of the dowel.

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Tying the cords to the pole

Step four:
Loop the longer rope (tied off at both ends) over the dowel. Then tie a clove hitch, using the free end of the shorter cord, so that the clove hitch goes over the longer cord, and secures it to the dowel (see photo above).

Once you get the clove hitch tied, lift up the assembly, and see how the bucket is hanging. It will probably hang unevenly, so adjust all the cords until it hangs more or less evenly — this is much easier if you get someone to hold the dowel for you. When everything looks even, snug up the clove hitch so it’s tight. (You can also tie off the free end of the rope onto one of the other ropes, using two half hitches — this makes for a slightly more secure assembly, although it isn’t really necessary.)

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Person in ancient Judean costume with loaded shoulder pole carrier

Above is what the whole thing looks like when it’s completed, with each bucket filled about 1/3 full. Don’t fill the buckets more than half full — if you do, the water will slop all over your feet when you carry it, and there’s a good chance you’ll snap the dowel from the weight.

In fact, for most school-aged children, filling the buckets about a third full will provide the most pleasant experience. With that much water in the buckets, it’s heavy enough so that the water carrier stays in place on the child’s shoulders, but it’s not so heavy that it hurts. Notice that the dowel in this design is relatively thin so that it acts as a spring, providing some cushioning to the shoulders — carrying water with this water carrier is relatively comfortable.

Of course, you can also use this type of carrier with a heavier load in the middle, and with two people carrying, one on each end of the pole. Obviously, a longer, stronger pole would be needed.

If you want to carry bigger loads with a shoulder pole carrier, use a heavier pole. Asian cultures often use bamboo for the pole — it’s a material that’s light, flexible, and strong. Traditional European shoulder pole carriers were typically less flexible, and carved (like ox yokes) to fit around the neck and put more of the load on the shoulders.

Invertebrate pitfall trap

When we humans think about the interdependent web of life, we tend to think about the relationships between ourselves and familiar organisms like mammals and trees. These are organisms that are either larger than us or relatively close to us in size, or they are taxonomically close to us. But if you conduct a survey of biodiversity in a given tract of land, the majority of non-microscopic species you find will be invertebrates, e.g., insects, spiders, crustaceans, etc. For a more realistic theological understanding of the web of life, I think it’s necessary to develop a more realistic understanding of biodiversity. It is easy and fun to feel a connection through the web of life to relatively cute organisms like rabbits, and to relatively majestic organisms like redwoods. Understanding our connections with organisms that are not particularly cute or majestic expands our idea of the interdependent web of life.

A few years ago, I participated in a blogger’s bioblitz; a bioblitz is a study that provides a “snapshot of biodiversity.” One of the tools used in a bioblitz is an insect pitfall trap; this kind of trap provides a sampling of insects and other invertebrates. I decided to place an insect pitfall trap in our front yard, so I could see some of the invertebrates that live in our urban setting.

Some online research revealed that pitfall traps made of glass are most effective (Oecologia 9. VI. 1975, Volume 19, Issue 4, pp 345-357), but the easiest way to make a pitfall trap is with nested plastic drinking cups. You dig a hole deep enough to bury the two nested cups, and pack dirt around them so that the rim of the upper cup is exactly at ground level. Then you can remove the upper cup, dump out all the dirt that fell into it when you were burying it, and then replace it. I used two nested 10-ounce clear plastic drink cups:

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To use pitfall traps ethically, you should check them at least once a day, and either release the captured organisms or collect them responsibly. If you’re expecting rain or hot sun, you should place some sort of cover over the trap, raised up an inch or two. The cover will keep rain and sun out, but still allow invertebrates to crawl into the trap. If you’re no longer going to use the trap, pull it out of the ground.

Here’s what I found in my pitfall trap this afternoon:

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The large organism appears to be in the genus Stenopelmatus; from looking at online identification guides, I’d guess this organism is probably a Dark Jerusalem Cricket (Stenopelmatus fuscus [Haldeman, 1852]). Where does it fit into the web of life? According to the Nevada at Reno Department of Extension: “Because it is nocturnal and comes out of the ground at night to roam around, owls, including the endangered spotted owl, feed on it. Probably other nighttime predators such as coyotes, foxes, and badgers eat it as well.” As for their food sources, the Orange County (Calif.) Vector Control District (OCVCD) says the primary food sources of Jerusalem Crickets are “plant roots and tubers; however, “they also feed on other insects, even their own kind.” The OCVCD also states that Jerusalem Crickets do not pose a health threat to humans.

The other organisms in the trap — you can see something like a centipede under the Jerusalem Cricket’s left antenna — were too small for me to have any hope of identifying. Besides, if I’m going to accurately identify insects and similar invertebrates, I’d need to ask an entomologist equipped with powerful binocular microscope.

More about insect pitfall traps.

Concrete block rocket stove

This past Sunday, the middle school ecojustice Sunday school class cooked on rocket stoves. We based our stoves on design principles developed by Dr. Larry Winiarski, who is affiliated with the Aprovecho Research Center. A rocket stove makes more efficient use of biomass fuels (wood, twigs) through more complete combustion; this also results in fewer harmful emissions. According to the Aprovecho Research Center:

“Improved cooking stoves address at least 5 of the 8 United Nations’ Millennium Development Goals: [1] ending poverty and hunger; [2] gender equity; [3] child health; [4] maternal health; and [5] environmental sustainability.”

So while we don’t really need rocket stoves here in the Bay area (except perhaps in disaster situations), learning about and building them is a great introduction to using appropriate technology to meet ecojustice goals of human well being and environmental sustainability.

If you’re not familiar with rocket stove design principles,Aprovecho Research Center has an excellent introduction on this Web page. Scroll down and click on document no. 8, “Design Principles for Wood Burning Cook Stoves,” June, 2005.

Enough background. Here are instructions for building a concrete block rocket stove, followed by photos of our rocket stove in action:

Click the image above for a drawing of how to build our concrete block rocket stove. You will find other plans for a concrete block rocket stove on the Web, but those plans typically require a concrete h-block, an oddball type of block that we were unable to find. However, most bit home improvement stores carry 8 x 2 x 16 inch concrete cap blocks, and 4 x 2 x 8 inch concrete brick — two cap blocks and two concrete brick can be arranged in an “H” shape to make a stove. In fact, this is a better solution than a concrete H-block, because you can adjust the concrete brick such that you have a constant cross-sectional area throughout the L-shaped combustion chamber (see “Design Principles for Wood Burning Cook Stoves,” principle 7).

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Above: The concrete block rocket stove after use. We placed two concrete bricks on the top on which to place cooking implements, etc. The bottom concrete block serves as a convenient place to store fire wood. Notice that our firewood is all salvaged building materials and wood pallets, split to appropriate size for burning.

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Above: Cooking on the stove. “Design Principles for Wood Burning Cook Stoves” states that a combustion chamber with a 12 x 12 cm cross sectional area is “usually sufficient for a family sized cooking stove.” Our concrete block rocket stove has a cross sectional area of 12.5 x 15 cm. It put out a good amount of heat for cooking scrambled eggs for half a dozen people. Note that one person is feeding the fuel into the stove, while the other cooks — we found it was challenging to cook and tend the fire at the same time.

We did not try to boil water on our concrete block rocket stove, to see how long that would take. Maybe that’s a task for a future class.

Update, one year on: This has proved to be a good, but not excellent, rocket stove design. The chief problem with this design is that the concrete block acts as a fairly large thermal mass, and it takes a while to heat the block. Once the block is warm, the stove functions pretty efficiently; while the block is still cook, it’s not as good. Another problem is that the stove is finicky, and requires constant attention to feeding fuel in order to maintain a fairly constant temperature. Nevertheless, given the low cost of materials, and the ease of construction, this remains a practical design.