Why Clay Makes Good Ceramics

 

These two things have ceramics in common, even though they are separated in time by 5,500 years.  Valdivia figurine and Space Shuttle

These two things have ceramics in common, even though they are separated in time by 5,500 years. Valdivia figurine and Space Shuttle

People have been using clay since the Stone Age, but what exactly is it? Why does clay make such good ceramics?

What is clay?

Clay forms wherever rocks that contain aluminum and silica are exposed to air, water, or steam. It’s all over the place, in other words – from mountains through volcanoes and geothermal fields to the ocean floor – and usually mixed in with a lot of other organic and inorganic stuff.

Not surprisingly, clay doesn’t have a single chemical formula. It is defined by its physical properties, and you can easily guess what these are. Clay absorbs or loses water easily, for instance, and it swells when wet.

Here are the two key properties of the clay group of minerals when it comes to ceramics:

  • They’re soft and made of tiny crystals (less than 0.004 mm in size) that are arranged in sheets
  • Some are plastic when mixed with a little water – you can deform them and they will hold the new shape

That plasticity, of course, is why we started using clay in the first place. No one is sure why it happens. Small grain size, chemical bonding, and water’s lubricating effect on the stacked crystal sheets all certainly have something to do with it.

There are three basic types of clay minerals, but we’re just going to look at the type of clay that’s usually used in ceramics.
Continue reading

5 Major Ways Sodium Improves Your Life

 

Did you know that sodium is an alkali metal like lithium and potassium?

Is it also “evil,” i.e., explosive, like potassium in water?

Yes. Yes it is.
 

Like its companions on the periodic table, sodium is too reactive to exist by itself in nature. It forms compounds, some of which are incredibly useful to us.
Continue reading

Guest Video: A Career in Surveying

 

Table_of_Surveying,_Cyclopaedia,_Volume_2

Time is a bit tight this week, so there will be guest videos from today through Thursday, and then a big post about firestorms on Friday.


Today let’s check out land surveying in Canada. Although this is a recruitment video (I know nothing about the company), it gives a nice overview of the basic surveying process, both in the field and in the office.

How things have changed since I did this while earning a two-year forestry degree back in the early Eighties! (Yes, we did use transit and level, as well as actual chains.)
 

Potassium and Your Body

Potassium is a metal like lithium, but no one builds batteries out of it because it’s evil:
 

Well, the human body is mostly water – why don’t we explode after eating a banana or taking a supplement?

That doesn’t happen because the pure metal those scientists are playing with doesn’t exist in nature – they made it in the lab.

Potassium oxidizes very quickly (the tarnishing that one scientist mentions), turning into a positively charged ion that’s actually water-soluble and quite stable.

It substitutes nicely with ions of other elements to form minerals (for example, switching places with plagioclase’s sodium ions to form orthoclase).

There’s another connection between potassium and sodium ions that is vital to all living beings, including you and me. It’s called the sodium-potassium pump.
 

Whee!  Source

Whee! Source


Continue reading

Career Opportunities in Urban Forestry

shade

The forest that grows along city streets and in parks needs conservation and provides jobs, too.

Trees bring many benefits to a city, including shade, better air quality, and beauty. The more, the better! There are many career opportunities for urban foresters today, and the job outlook is good.

Trees bring many benefits to a city, including shade, better air quality, and beauty. The more, the better! New York City has some 5.2 million trees. The forest in Los Angeles is almost twice that big. There are many career opportunities for urban foresters today, and the job outlook is good.

Urban forestry jobs

All foresters are team workers. They spend a lot of time outdoors, keeping trees healthy and monitoring water and soil quality. Foresters maintain tree inventories and map property lines. They plant new trees as needed and select and mark trees for cutting when disease, pests, or storms cause damage.

Indoors, you will find them training and supervising other workers. Communication with the public, as well as with scientists, officials and other foresters, is also an important part of the jobs.

Urban foresters face some unique challenges. When a big tree must be felled downtown, they just can’t rev up the chainsaw and yell “Timber!” It takes planning, extra work, and sometimes even cranes and other heavy equipment that also come in handy when, for example, a street is being widened and trees must be moved and replaced.

Urban trees are very stressed. They may not be planted properly. There is more air and water pollution, and the city environment is hot. Pavement and drains keep water away from the roots, too.

Urban forestry is a tough job, but it also has its rewards. Trees beautify and cool a city. They clean the air, reduce storm runoff, and attract birds and other wildlife.

An Eisenhower ash in Cohoes, New York, serves as a World War II.  This tree is one of thousands cultivated from seeds of a green ash growing at President Eisenhower's birthplace in Denison, Texas.

An Eisenhower ash in Cohoes, New York, serves as a World War II. This tree is one of thousands cultivated from seeds of a green ash growing at President Eisenhower’s birthplace in Denison, Texas.

Most importantly, the forest engages the community. It takes many hands to plant and maintain a tree. People also like to gather in parks, on bike paths, or even just for a quick outdoors lunch on a shady corner.

Job requirements

For an entry-level position, you will need an associate’s degree from an institution accredited by the Society of American Foresters. Two-year college programs offer fieldwork but typically are meant to integrate with a bachelor’s program. Technical institutes will focus more on the practical aspects needed to get a job after graduating.

Newcomers usually start off working under an experienced forester. Fifteen states require credentials. This generally takes at least a four-year degree as well as work experience.

All forestry is physically demanding. Prepare for doing heavy work, like climbing trees or chain sawing, in all kinds of weather, including extreme heat and cold. Emergencies happen, too: a neighborhood of trees toppled by severe weather, power outages during an ice storm; or even a fire in the municipal park during a drought.

Job outlook

The median annual wage for foresters was $33,920 in 2012. Most foresters work for the public sector, so budget constraints are a factor, at least at the federal level. The United States Department of Labor predicts a 4% decline in all forestry jobs through 2022. However, it’s also true that many current foresters will be retiring soon, so there will continue to be job openings with the federal government.

Urban forestry is also especially useful to local and state governments. Jobs are there as well in the private sector – tree services, for example, as well as landscaping, conservation or environmental businesses.

The forest doesn’t stop at the city limits, and it always needs professional care. Urban forestry jobs are out there. Get the training and experience you need, build up some physical stamina, and go for it!
 
 


Sources:
 

Trees for People, Urban Forestry 101. United States Department of Agriculture

Forest and Conservation Technicians. Bureau of Labor Statistics

U. S. Department of Labor Environmental Career Outlook. University of Florida

Foresters Overview. Campus Explorer

 
 

This article first appeared at Yahoo Voices, earlier this year.