Publications general

Gepubliceerd: 01 december 2016

Just stones?

Tumbled stones are small pieces of rocks and minerals (usually about one to five centimeters in diameter) that have been processed in a rock tumbler to produce smooth, rounded and highly polished pebbles. Most stones that a person can find will not tumble with good results. The rocks and minerals used to make tumbled stones are specially selected for their color, translucence, appearance and ability to accept a high polish. These special materials are known as "tumbling rough". Some people collect their own tumbler rough and some buy it from a hobby supply store. Tumbled stones are often so beautiful that many people call them “tumbled gemstones.”

Tumbled gemstones are used to make jewelry, craft projects and other decorative items. They are also widely collected by people who appreciate their beauty and have always been associated with spiritual and healing properties by some superstitious people. They are especially enjoyed by children. Tumbled gemstones are extremely popular in gift shops – especially gift shops found at science centers, caverns and other natural science attraction s. Many geologists obtained their first interest in rocks and minerals when they received tumbled stones as a gift or discovered them in a store.

Gepubliceerd: 29 juni 2016

Art, design and crystals

Art, design and crystals
In her studio in the Port of Rotterdam the innovative artist and designer Liesbeth Bulk is experimenting with the growing of crystals on everyday and design objects. She tries to combine the beauty of crystals with the structure of objects. Mastering this artistic and technical challenge is still at an initial stage. Until now, trials have been carried out with sugar crystals. When we look at the picture taken with a Motic stereo microscope, it is not surprising that artists are fascinated by the beauty of crystals and start experimenting with them, as can be seen on the image below, showing a small part of Liesbeth’s art lab.

liesb

Liesbeth is a designer with a fascination for nature, she also creates bespoke glass panels with enclosed natural elements. With profound knowledge of plants, the flowers, leaves and twigs are collected in the wild. Searching for a way to merge the lush plants with monumental, architectural characteristics, she started experimenting with the forgotten technique: pressed flowers.
Liesbeth Bulk (1968) studied garden design at the Horticultural college in Boskoop, The Netherlands. In 1998 she completed her studies at the Sandberg Institute (post academic course at the Gerrit Rietveld Academy Amsterdam) with a masters in fine arts. For examples of her work use the links below.
Source: www.crush-on-nature.nl and http://www.liesbethbulk.nl

Gepubliceerd: 01 april 2016

Wool, too tight for comfort?

Wool has been a precious raw material for people for a long time. Yarns have been spun out of wool fibres for several millenniums. As the range of available fibres was limited in the past, wool used to be a very valuable commodity. Today we are able to select between a huge variety of fibres with varying properties, but nevertheless, the percentage of wool in fibre production all over the world averages out to a few percent.

The continuing use of wool – in spite of the competition with other natural fibres and new synthetic fibres – for suits, coats and pullovers can be attributed to the unique properties of wool:
- thermal regulative due to high amounts of air embedded in the fibre
- high absorption of moisture
- low tendency to creasing
- low flammability

However, wool has not just got properties which offer high wearing comfort. A big disadvantage, which emerges during washing, is the felting tendency. Under the influence of warm, alkaline water, the scales surrounding the wool fibres rise. If the wool fibres are additionally moved, the fibres wedge with each other more and more since they can only glide in one direction due to the scales. The fabric shrinks and gets tighter.

To prevent felting of wool and to make wool washable in normal household washing machines, several methods have been developed:
- softening/removing of scales by chemical modifications (oxidation)
- covering of scales by application of a resin
- combination of oxidation and enzymes
- plasma treatment
- combination of removal and covering (so called Chlor-Hercosett-process)
- Petry-anazym-proces

Gepubliceerd: 01 december 2015

Urea, a chemical indispensable for life

Urea is an organic compound with the chemical formula CO(NH2)2. The molecule has two NH2 groups joined by a carbonyl (C=O) functional group. Urea serves an important role in the metabolism of nitrogen-containing compounds by animals and is the main nitrogen-containing substance in the urine of mammals. It is a colourless, odourless solid, highly soluble in water and practically non-toxic. The body uses it in many processes, the most notable one being nitrogen excretion. The average person excretes about 30 grams of urea a day, mostly through urine, but a small amount is also secreted in perspiration.

Synthetic versions of the chemical compound can be created in liquid or solid form. Urea is widely used in fertilizers as a convenient and indispensable source of nitrogen. Urea is also an important raw material for the chemical industry. It is used to produce some types of plastics, animal feed, glues, toilet bowl cleaners, dish washing machine detergents, hair colouring products, pesticides, and fungicides. Medicinally, it is used in barbiturates, dermatological products that re-hydrate the skin, and diuretics.

Gepubliceerd: 01 augustus 2015

Multipurpose polyester

Polyester is an umbrella term that describes a manufactured fiber whose substance is any long-chain synthetic polymer, where at least 85 percent (by weight) of the polymer is an ester and terephthalic acid. Most polyester is made of polyethylene terephtalate. The properties of polyester fabrics vary depending on their composition, web structure and processing, but some general features are found with nearly all polyester fabrics.

Polyester is a strong and durable synthetic fabric. Polyester dries quickly and can be washable or dry clean only. Polyester is often used as a blend with other fabrics to lend wrinkle resistance. It is not the easiest fabric to remove stains from, and doesn't breathe as well as other fabrics may.

Fabrics woven or knitted from polyester thread or yarn are used extensively in apparel and home furnishings, from shirts and pants to jackets and hats, bed sheets, blankets, upholstered furniture and computer mouse mats. Industrial polyester fibers, yarns and ropes are used in tire reinforcements, fabrics for conveyor belts, safety belts, coated fabrics and plastic reinforcements with high-energy absorption.

Sources: Ehow, Wikipedia

Gepubliceerd: 25 april 2015

Crystal clear and colorful

Crystal structure of Phenyl-2-hydroxybenzoate or phenyl salicylate, or salol, is presented here by using polarization microscopy. It is a chemical substance, introduced in 1886 by Marceli Nencki of Basel. It can be created by heating salicylic acid with phenol. It appears in the form of small white crystals or crystalline powder with pleasant aromatic odour and taste. Once used in sunscreens, phenyl salicylate is now used in the manufacture of some polymers, lacquers, adhesives, waxes and polishes. It has been used as an antiseptic based on the antibacterial activity upon hydrolysis in the small intestine. It acts as a mild analgesic.