Monday, February 26, 2024

Firing Primitive Pottery

Pre-heating around a premier fire
Cow-dung fire
Fired wild-clay objects with carbon staining
Wood fire -- attempt to burn off the carbon
Sadly, even more Carbon staining Some science behind all of this. Ignore the kiln comments, they do not apply to my firing method · Jeff Zamek · · “The pot fills the gap between art and life.” Philip Rawson, Chubut, Argentina What’s happening when heating and cooling my kiln? If you make ceramic sculpture or pottery and look at a firing kiln this question must come to mind. As the temperature increase reactions are occurring and clay and glazes are changing in irreversible ways. The pottery that comes out of your kiln will be the last objects left when our sun ends its life and consumes the earth. 212 0 F. – 392 0 F. 100 0 – 200 0 C. Mechanical water is removed from the clay particle surfaces. 842 0 F. – 1112 0 F. 450 0– 600 0C. Chemical water is driven off as in the clay formula Al203 2Si02 2H20. During the mechanical and chemical water removal range if the kiln is fired too fast pots can crack or blow up often damaging adjoining pottery. 1067 0 F. – 575 0 C. Quartz in the clay goes through a sudden expansion at the same time that shrinkage occurs in the 842 0 F. to 1112 0F. - 450 0C. to 600 0C. If the kiln is fired up too fast or cooled too fast during this range pots can crack. 572 0 F. 1292 0 F. – 300 0 C. 700 0 C. Sintering, Earthenware Firing the kiln in complete oxidation will remove organic matter in the clay. Excess oxygen and time will promote a clean bisque firing. Incomplete oxidation can leave carbon in the clay resulting in bloating at higher temperatures. 1922 0 F. 2012 0 F. - 1050 0 C. -1100 0 C. Spinel (a group of minerals of the same structure and formula) develops from the metakolin changing to mullite needles. Feldspar starts to melt into a glassy phase dissolving silica from kaolin forming mullite. The clay body becomes dense and vitreous. 2192 0 F. – 1200 0 C. Vitrification? Feldspar continues melting into a glass phase decreasing porosity in the clay body. 2012 0 F. 2282 0 F. - 1100 0 C. 1250 0 C. Stone ware?. Any quartz in the clay body changes to cristobalite while other fluxes in the clay body and feldspar aids in the quartz to cristobalite conversion. On the cooling cycle cristobalite inversion occurs around 392 0 F. -200 0 C. If the kiln is opened prematurely at this range some glaze pinging can be heard. Additionally, wood fired kilns and kilns with low B.T.U. capacity frequently slow down or stall out after cone 8 (2280 0 F. – 1249 0 C.) and can develop excessive amounts of cristobalite which can cause pots cracking in typical oven ware temperatures. Kiln Insulation – Commercially made kilns are designed with the appropriate thermal gradient in terms of insulation properties. When planning any kiln building project investigate the insulation options for the type of kiln being built. Under Insulated Kilns that are under insulated can be expensive to fire due to extensive heat loss during the firing. Under insulated kilns might not reach temperature or take excessively long to achieve clay body and glaze maturing temperatures. In enclosed kiln rooms there is the potential problem of the potter’s safety due to high kiln room temperatures. There are clay body and glaze defects caused by firing kilns too fast or too slow (see other blogs). Over Insulated Conversely, kilns constructed with high levels of insulation can coast. If you have noticed at the end of a firing that pyrometric cone 9 is at the 3 o’clock position bending and the next day when opening the kiln the cone is at the 4 o’clock position the cone has been subject to “heat work” which is the result of temperature over time. When the heat source has been turned off the cones are in the maturing range longer due to the greater degree of kiln insulation. In some instances this situation can cause glazes to run or appear over fired in color and/or texture. Matte glazes can appear glossy or satin matte while glazes containing high percentages of metallic coloring oxides can run on vertical surfaces or pool in horizontal surfaces. Slower cooling rates can promote crystal growth in glazes. Porcelain clay bodies can stick to the kiln shelve or deform when subjected to prolonged times in their maturing temperature zones. This is due to their highly vitreous composition as opposed to stoneware and earthenware clays containing lower glass formation. Dense “accordion pleated” packed fiber kilns and kilns constructed of only hard bricks can be over insulated subjecting pots to excessive heat work in the cooling cycle. Hard brick kilns take a long time to heat and cool due to the density of the brick which has to be first heated to then radiate heat to the pots. Hard brick kilns take longer times to cool due to their increased thermal bank radiating heat. When to unload the kiln Under ideal conditions it is a good policy to let the kiln cool to room temperature before opening and unloading the pots. Not many of us do that! As a safe alternative a bisque kiln can be unloaded below 300 0 F. – 148 0 C. as the pots are not dense enough to be thermally shocked. However, be aware the kiln shelves, posts and pots can still be hot enough to burn you. Potters and bakers frequently have burn scars on their forearms from reaching into the kiln and ovens burning themselves on the still hot shelves. When opening a glaze kiln try to unload below 200 0 F. – 93 0 C. but if you still hear glaze pinging close the kiln and wait till the temperature drops below 100 0F. – 37 0 C. These unloading guidelines can be adjusted depending on your level of risk however, it is always best to wait when in doubt. Information sourced from, Ceramic Science for the Potter by W.G. Lawrence, Professor Lawrence taught at Alfred University

Tuesday, September 5, 2023

Pros and cons of private Insect collections

Insect collecting At the moment, huge Dynastes grantii and pretty Chrysina spp are flying in our sky islands and landing under bright lights. They are tempting many nature-lovers even from out of state, to begin an insect collection. Indeed, collecting is a great way to learn about insects, and this knowledge hopefully leads to understanding and protection of environment and habitat. A well curated collection can be a valuable teaching tool to draw in others, especially kids. But: anybody who thinks he or she needs a collection should really consider the scientific validity of that enterprise. I am not saying that the ecosystem gets damaged by the withdrawal of a few individual insects. Where you find some, there usually are many more and as imagoes (adults) their lifespan is very limited. Any individual producing offspring produces such number that any dents in the population (by collecting) are easily filled. But to feel good your about collected insects, you need to prepare them carefully, label each one with collection data (more important than species ids!), dry them properly and keep them in a protective drawer (and those will be accumulated in cabinets, then whole bug rooms!) away from carpet beetles etc. For killing and preservation, toxic chemicals are used. This is some great effort, but it should be undertaken out of respect if you are going out to kill animals. Even today It is still possible, especially out west, to find new species or contribute important data to ecological surveys. Of course, the hobbyist has to understand that the large, showy species are usually well known and new data and exciting research results are rare. With the enormous diversity of insects, not many hobbyists can become knowledgeable experts of the whole phylum. Compare species numbers to those of birds or mammals and you see what I mean. However, specialization on families within orders allows even a lay person to accumulate enough knowledge to contribute. But you have to make yourself appreciate smaller, less charismatic specimens than just the big scarabs and longhorn beetles. Detailed observation and inclusion of the small and overlooked species will make a collection relevant and important beyond just a pretty wall decoration. In due course, If the collection is well cared for and scientifically interesting material is accumulated, it should later be made available to research and teaching in a museum or university setting. Collecting used to be the only way to really learn about insects, because reliable identifications in the field are difficult. Optical instruments and dissections may be needed, and good field guides are hardly available when compared to what’s out there for birders. To a certain degree, this situation is changing. With easy access to good macro-photographic equipment (even I phones!) much can be recorded and identified without the actual specimen in hand. Internet platforms like BugGuide and INaturalis and even our SW Arthropods group on Face Book (I am NOT suggesting to ‘just google it’) connect the naturalist to experts who are willing to help with their knowledge and who in turn gain access to data from the crowd of observers. Of course whenever something interesting is shown on those platforms, the experts will clamor for specimens, not just photos (with good reason). But still the beginner should probably use photography and internet platforms to learn the basics before he or she starts collecting and gets stuck with a pretty, showy, but in the end not very interesting collection of just Hercules Beetles, Silk Moths and pretty butterflies. That way, the collection may eventually become much more satisfying than just a wall decoration.

Saturday, July 15, 2023

Gila Woodpeckers in Saguaro Boots

On the 7th of May, a friend visited with her family to look for nests in Saguaros. Tucson Audubon had offered some kind of sponsorship reward for finding those. So we looked at Raptor nests, a White-winged Dove, House Sparrows. The dad of the family heard fine chirps from above: deep inside the stem of a saguaro a clutch of Gila Woodpeckers had just hatched. Gila Woodpeckers and Gilded Flickers hammer holes deep into the stem or a big arm of our giant cacti. This nesting cavity is not used in the year when it's built. But soon the cactus encloses the cavity with heavy sclerotized layer of scar tissue. So now there is this hard, inverted bag hanging inside the cactus, reaching in, then curving down, as big as a boot. It is surrounded by the moist, water-storing tissue of the cactus and parts of the wooden saguaro skeleton. It's impenetrable to most predators. Most importantly, it's isolated from temperature fluctuations by the huge amount of water-holding material around it. Desert nights can be cold, daytime temperatures are extremely hot. Eldon Braun of the UoA found in his master-thesis research that the daily fluctuations inside of several Gila Woodpecker nests never exceeded 14C, even if the nights hovered around 10C and the daytime high was way over 40C (scientists use Celsius measurements). Great conditions for the woodpecker brood to grow up in. At the same time young dove chicks in their flimsy nests nearby experienced the full impact of heat and cold. Surprisingly, most dove nests produce fledglings anyway. But not surprisingly, the baby doves develop very quickly (high protein crop milk helps) and then they are out of the nest. Precocious quail chicks run from their ground nests even faster - on the day of hatching! However, the Gila Woodpeckers that we heard chirping faintly on the 7th of May are still in their 'Saguaro boot' today on the 15th of July! Now their chirping is not faint anymore, but loud and demanding! They are probably close to fledging, but still holding out. Who would be eager to leave the climatized safety of the inside of a huge cactus column for the punishing heat that the outside desert is experiencing right now? But when they do decide to fledge, monsoon rains will hopefully be right around the corner to cause scores of insects to emerge that the young woodpeckers will devour. Still, the juveniles also learn very quickly to get refreshments from our hummingbird feeders. Soon!

Thursday, July 6, 2023

Pre-Monsoon Ordeal

Our Patio has a deeply overhanging roof. At 110F it becomes a shady retreat for all kinds of animals close to heat exhaustion. I just went outside to spray the floor so the evaporating water will cool it down even more. There are flies on the walls. Whiptail lizards moving between some planters. An Antelope Squirrel appearing shortly between the pots. Not used to being so close to the house, it nervously hides from view. Two Cottontail Rabbits stay in the periphery. They may be aware that 3 big, fast dogs live here (indoors today). And scores of birds. They are annoying the Costa's Hummingbird that always lives here, for nearly a decade now (does an individual get that old or is he part of a dynasty? Cactus wrens investigate every corner. Mourning Doves sit quietly. Verdins are part of the army that seems intent on denuding my pepper plants of their last leaves. The female Cardinal has just raised a demanding brood. She'd deserve some rest. Instead she pants with her parrot beak wide open. A Say's Phoebe flutters along the wall. No 'burgfrieden' for the flies on the wall. Last year, in a window niche I saw a form of that (look up the German word if you must) A rattler tucked into one corner, a Sonoran Desert Toad sitting in the other one, a packrat nervously running between them, oblivious to the rattler that she occasionally stepped on. But back to today. No snakes so far. Sharp whistles announce Curvebilled Thrashers, a youngster and a parent. A family of House Finches occupies table and chairs. Abert's Towhee is a very unusual visitor though years ago we had nesting Canyon Towhees who long since gave up on this dry part of desert. Several Gila Woodpeckers divide their time between our Hummingbird Feeder and the last Saguaro Fruit (we have a huge pair of saguaros very close to the patio roof and can only hope that they never fall down on us) Ashthroated Flycatchers grab last nights drowned scarabs from a water dish on the window sill. I follow with my eyes and suddenly realize that I am looking at a sleeping Screech owl in the corner of our bathroom window. A sound erupts close to the ground - like the call of the Flycatcher, but less self-assured and loud. A Red-spotted Toad. So the monsoon IS coming?

Friday, December 30, 2022

Common Names versus Scientific Names

I saw an article once that investigated the relationship between 'caring about', general interest, and approachable nomenclature. I agree with the author of that article that there is a relation (I am avoiding judgemental words like correlation or causal connection) that goes both ways. People don't care if they can't relate to something, but also, true specific common names are not created when there is no interest. And just negative interest that generates names like Murder Hornet or Fire Ant or Kissing Bug or Brown Recluse is not really enough either: People love to throw those names at anything related (any wasp or ant or bug or spider in this case) that scares or stings them. There are other examples that are more positive like the 'common' names created for Butterflies, Tigerbeetles and Dragonflies. All three groups have a positive reputation to begin with, so English species names were created, just like for birds. How accepted are those? Are they just another layer of labels that we scientists now have to learn? Is the general public now more interested? That remains to be seen. Another question is of course how common common names really are. They can really only apply to the audience of a few countries where folks happen to use the same language (an easy decision for the author of a book that is usually written in only one language anyway. But insects do not live only within the borders of those countries (see US and Mexico) and people, especially naturalists tend to travel. Germans certainly do. In Germany the general interest in insects has always been greater and less negatively bent than in the US (my opinion). So over the last 30 years a German name has been assigned to just about every European insect species. Of course total numbers are small compared to the US/Mexico/American complex. But since Germans really do travel, they seem to have German names even for most species they photograph in the US. And the names are clumsy and long because they try to convey at least as much info as the scientific genus-species complex carries. For the birder: Grosser Rennkuckuck? The Roadrunner, who actually is related to Cuckoos. I left Germany before all those interesting names were coined. In each country I stayed in long enough I acquired a new set of hundreds of bird and mammal names (my brain was younger then) and I was very happy that most of the scientific names of insect and plant genera kept their validity. The splitting-off of New World species from Old World species that used to share the same genus name started more recently, and since that comes stepwise I try to keep up. But I still carry a lot of USAmerican Aphodius spp in my mind ....

Saturday, November 26, 2022

Moving across the country in 1991

I just ran into this photo (by Amazing Nature) - I won't ever forget my last night in Florida before moving to AZ in 1991: Standing between flooded areas of Paines Prairie, shining lights over the water and catching the eye shine of scores of alligators. Standing in the way of a fire ant tribe on the move, probably because of the flooding. Suddenly feeling dozens of them attacking my lower legs, simultaneously, as if on command. The next day, on the way north in Tallahassee I ran into the big Limulus mating on the beach. I had never even heard of that phenomenon. Along several states, I 10 seemed to be the only road not under water. In Baton Rouge my motel neighbors were so noisy that I went over to ask what was going on: They were celebrating that they lost three boats in the storm (crab fishers) but nobody was killed. They invited me to their church the next morning. Texas was endless, but the peaches were great. A whole box of them was stored on the head rest of my car , their aroma competing with the stench of 3 huge dead Limulus that I could not leave behind. I saw ranches that bred paint mules as big as horses. In NM I was invited by an old mountain rancher to help round up his cattle. On the Continental divide my old Golf Diesel over-heated, being loaded with all my stuff and dragged up to some cliff dwellings in the San Juans. At the border to AZ a dust storm closed I 10 (it was the fourth of July). I arrived in AZ 4 days after leaving Gainesville with great memories and legs spotted with ant stings that seemed to last for weeks. All that was part of a totally unplanned move from my first US job that I hated to accept an invitation to work at the U of A instead. From the people who put me up for my first night in AZ I traded 2 dead Palo verde root borers for one of my Limulus skeletons, but their cat chewed them up before the night was over ...

Saturday, October 30, 2021

My ode to impermanency

As a child, I got to plant a tree. But when I sold our house, the new owners cut it down. I recorded my songs, but the tapes eventually unspooled themselves and got irreversibly tangled. I read and studied and was proud of my language proficiency until I migrated and had to start over. I trained horses and dogs,but they got old and died. I photographed artfully and spent much time and moneyon film, but the medium of slides became obsolete. I fought to establish a wetland nature preserve, and against a freeway planned to cross through it. When I returned after 30 years, it the groundwater level had fallen, and the marsh was dying. I invested in friendships and love, but I or the friends moved away, and the connections were reduced to facebook messages. I collected books, bird nests, and art but abandoned them on another continent to people who did not care. I painted and sold my work, but the people who bought my paintings got old and their heirs had different tastes. I am working on a book when the medium of print might be reaching the end of its 400 year reign. The tree was a birch that we brought back from a trip to the Dutch border in a pot. I watched how the huge leaves of the young tree turned over the years into much smaller leaves of the mature. It grew over our heads, gave us shade, a place to climb up in, where birds would roost, and leaf-rolling weevils perform their art. It sparked feuds with neighbors over falling catkins, seeds and leaves. It lost a limb one spring and produced so much ‘Birkenwasser’ that we all washed gloss and health into our hair. It gave character to our house. In the evenings we often sang under the tree, learning songs in a foreign language because we felt that our own folk-songs were infused with a patriotism that left a bad taste in our mouths. There we easily threw out the good with the bad. But enthusiastically we sang into microphones of primitive recorders, and mothers got years of enjoyment from it. Eventually, I made the foreign language of those songs my own. I had been very comfortable in my old language and deeply loved its writers and poets. But discovering new lands was exciting and invigorating. Even though for a while a new language makes any migrant feel like she is being reduced to the level of a 10 year old even in her thoughts, one eventually gets comfortable enough to believe that no loss happened, but new levels of complexity have been reached. Cognitive bias that makes us feel better. When I noticed that I used my new language to train my dogs, I knew that I had become quite comfortable. Of course, those dogs were not the beloved one that accompanied my childhood. That I trained and took to trials that he was not bred for and still got some awards. But I found a little bit of him in each of the others – and I loved many over the years. Only photos remain of most of them – a dog’s life is so short that I have begun to think of them as the continuum of ‘our dogs’. Always an avid photographer, I got my first camera at the age of five. My father had his own darkroom, and my parents’ best friend was an artist who worked in every medium imaginable, including art photography. Absorbing by osmosis rather than being taught, I early on tried to use the camera to capture and preserve memories, to create art, and to document observations of the natural world. My first greater investment of any kind was a state-of-the-art macro lens for my Canon A1. As digital technology began to replace film and slides, I made the switch later than many. I love now the instant feedback, certainly the endless availability of digital pixels, and that I can edit and change my photos without spending nights in a smelly darkroom. I miss the mystery of the image slowly appearing in the developing bath. I still think about graininess versus light-sensitivity and speed versus depth of field. Sadly, I got disenchanted with the quality and usability of my earlier slides to the point that I just left thousands of them behind when I sold our old house. I was under immense stress at the time and still regret that decision. But those photos that I cannot physically see anymore are ingrained on my brain and will forever be of superior quality and artfulness. I returned to the ‘old country’ after my mother died and I had to resolve her estate. It was a very sad time. I found solace returning to the woods of my childhood and the swampy nature preserve that I had helped to establish in the late seventies by doing the entomology part of our biodiversity assessment. Where in the first half of the last century mining activity had caused severe sinking of the ground and a reversal of the flow of the groundwater, trees had drowned, and agricultural fields had been lost to wetlands. These themselves were then considered worthy of protection because the country retained so very few of its original bogs and swamps. When I returned over 30 years later, the area was still protected by nature preserve signs, but a changing climate was drying out the soil and the forest was taking back the area. The change was fascinating to observe: While many of the insect species I had listed earlier were gone, I found many pioneer species and a very high level of diversity, as often the case in disturbed or changing environments. I would have loved to observe longer or at least to come back to it later. (The situation may have been reversed again after the floods of 2021 in NRW) A friend from my youth had joined me for this short step back in time. Disconnected from the past and any possible future, this encounter was blissfully sweet. Never a person to easily bond, I have left behind most of my closest friends at several points in my life. But I tend to keep most of them close to my heart, and whenever we meet again, I connect as if no time had passed. Most bad memories, though, have been erased. That cognitive bias again! Even my happy marriage is based on reconnecting to my great love after more than 15 years and another marriage in between. There was heartbreak in the past. But time has made that unimportant. Whenever I was lonely or sad, I found an outlet in creativity. I can trace back my most active times in nature photography, writing and painting to times of broken first love, a failing marriage, homesickness and other shake-ups. Painting especially always helps me to transcendent to a state beyond momentary pain and stress. So the reward I get from painting is manyfold. First, the process of painting is reward in itself. I really fight and work from the ‘ugly’ phase that any of my paintings goes through to the satisfaction of the finished piece. Watercolor, by its somewhat ‘accidental’ character, lives of surprising, unplanned effects. The art lies in letting them happen and enjoying them. Then, I get to show the piece. At shows, on-line, it’s usually a good experience, and I do not question what could just be flattery. The real test comes when it’s up for sale. I hate sounding so commercial, but it is a great compliment when someone is willing to pay my price and give the painting or print a prominent place in his home. People who buy from me are also always exceedingly graceful: they thank me – as if no money had been involved in the exchange. So the satisfaction is great on both sides, even if I am realistic enough to know that any change in the living arrangements of my clients can make my painting homeless again. My art is just not high end enough to pose a collectible value in every case (yet 😊). At the moment I am not producing much art. That could mean that I am just too blissfully contented. But in fact, I am pouring my creativity into the preparations for a book, my long dreamed-of Arizona Beetles. It has become somewhat of a never-ending story because we find more and more species to include, especially since my co-author, Art Evans, has now bought into my concept and obsession to make it as complete and inclusive as we possibly can. But the more time goes by, the more often I worry about several things: that I will not be able to work the market well enough to distribute it because I am doing fewer shows and fairs, that many of our followers may lose interest in field work and Arizona collection trips, that the insect fauna is so changed and diminished by climate change that our book becomes more of a historical account, and that books, as a medium, lose out to all those phone apps that promise identifications that are probably not as accurate, but fast and easy. On the other hand, the project has given me years of adventures in the field often in the company of great friends, much learning and discovery, hours of satisfying creative work at the computer. I would not want to miss a minute of it. Well, so much for any attempt at permanency. You say: but what will be left of you after you are gone? My answer is that at least I will not take up space from those who come after. Until then, I'm going to enjoy it while it lasts, whatever it is.