Glow In The Dark Items

Glow in the dark (GID) items are one of my favourites. I find them extremely usefull to mark light switches, radiator valves, keys and many more, especially for my outdoor equipment like zippers or tent pegs. The strongest glow in the dark powder I experienced so far, is the Glow Inc. Ultra Green V10 GID sand and, a little bit weaker, the GID powder. Because these strontium aluminate pigments are moisture sensitive, I usually mix them with epoxy resin or styrene resin.

Glow in the dark items

Glow in the dark key chains

Glow in the dark key chains

Chemistry: Some Fun with Freon

I recently get some vintage spray cans containing chlorofluorocarbons. Chlorofluorocarbons, commonly known as CFCs, are a group of man-made compounds of carbon, chlorine and fluorine produced as non-flammable, inert derivatives of methane and ethane. The Belgian scientist Frédéric Swarts pioneered the synthesis of CFCs as early as in the 1890s. The industrial production of CFCs began in the 1930s. Since then, they've been extensively utilised as propellants in aerosols, as blowing agents in foam manufacture and as refrigerants.
By the late 1970s, more and more the destructive effect of CFCs on the ozone layer revealed. There are no removal processes or sinks for CFCs in the troposphere. As a result they are slowly transported up into the stratosphere where they are broken down by UV-radiation from the sunlight, releasing free chlorine atoms (see formula mentioned below). The chlorine radicals initiate the ozone depletion by a chain reaction with ozone molecules. Also the strong IR-absorption bands of CFCs, mainly located in the spectral region, make them strong greenhouse gases. Since the dangers caused by CFCs to the ozone layer were first identified, their use has gradually been phased out, according to the Montreal Protocol in 1987.  However, CFCs have long lifetimes in the atmosphere before they are broken down by sunlight, and consequently they will continue to enhance the greenhouse effect well into the 21st century.
Today the antropogenic release of nitrous oxide replaced CFCs as the biggest ozone depletor.

So far on their history. The most common CFCs were CFC-11 (Trichloromonofluoromethane) and even more CFC-12 (Dichlorodifluoromethane). CFC-11 was used as a non-toxic and non-flammable solvent mainly for aerosol applications (b.p. 23.7°C), whereas CFC-12 was used as propellant or in refrigeration (b.p.-29.8°C) often called R-12. I extracted some of the CFC-11/12 (30%/70%) mixture from one spray can to show you the nature of CFCs: They look like ordinary water and are not inflammable. The mixture was odorless too, but on contact with fire a stinging odor like burning PVC from hydrochloric and hydrofluoric acid emerged. The mixture quickly evaporated at room temperature and boiled on contact with warm surfaces like my finger tipps.

Freon spray cans

Liquid Freon (Dichlorodifluoromethane and Trichloromonofluoromethane)

The CFC-11 / CFC-12 mixture already boils on contact with the skin

Bloomery: Double Action Box Bellows

Double Action Box Bellows

I built this box bellows for my bloomeries in 2011. This type of bellows is known from ancient asia only as far as I know, but I wanted to try them for my "roman" style furnances. The reason for that was, that I found it very inconvenient to handle the bellows and charging the furnace simultaneous. So I made a compromise, engaged some mechanics and constructed this ancient air blower, driven by an electric motor instead of the commonly employeed vaccum cleaner motors for this purpose.

The bellows is basically a modified -commercial available- wooden box with a wooden piston inside. On one side of the box I attached an air tunnel, receiving the compressed air of the bellows by two valves, which are on each end of the box. The air tunnel is enclosed at each end by wooden caps. In the middle of the tunnel I drilled the air outlet, as you can see on the photos. The piston is moved like an inversed steam engine, and the motor shaft is powered by a 350 W three-phase asynchronous motor (modified for two phase current by a capacitor)

The box bellows was made from a modified wooden box

The piston of the box bellows. A lining of coney fur was used as gasket

The air tunnel enclosed with a wooden cap

The final stage of the box bellows

The first runnings were performed by a belt driven worm gear

The box bellows with an adjustable friction gear in action

Detail of the motor unit

In the final stage the fixed driving speed of the bellows was stepless adjustable by a friction gear. With that modification the assessable air outlet was somewhat between 500 to 1000 L/min