There are plenty of things you can buy quite legally that will get your Geiger counters ticking. Perhaps the most common radioactive item, found in most homes, is the humble smoke alarm. Most models use a device called an ionisation chamber to detect smoke particles. Inside the chamber there is a small amount of an artificially produced radioactive isotope called Americium 241 (Am-241). The tiny radioactive pellet emits alpha and low energy gamma rays, which are mostly absorbed by the detector module's metal casing. However, very small amounts of radioactivity can escape and may be detected using instruments with highly sensitive ‘Pancake’ and scintillation type probes. Unfortunately these tend to be quite expensive and the probes are often delicate and easily damaged.


Another household product, available from most supermarkets, which emits very low-level radioactivity is ‘Lo Salt’, the low sodium alternative to common table salt. Again, there are measurable emissions from the Potassium Chloride it contains, that can be picked up by some of our more advanced instruments. Brazil nuts and cat litter are other well-known low-level sources, and step outside your home into the street and there’s a fair chance that the kerbstones and road surface are gently radiating. This is due to the presence of  granite, which can be surprisingly 'hot' due to it containing trace amounts of naturally ocurring unranium minerals.


In some parts of the UK (notably Cornwall, Devon and parts of Scotland), where the bedrock contains substantial quantities of granite you can find quite 'lively' radioactive rocks lying around on the ground, on beaches and around the spoil tips of abandoned tin and uranium mines. If you don’t fancy prospecting yourself – and it’s really not a good idea to mess about in old mines -- radioactive minerals are readily available from dealers and good old ebay. Small chunks of Uranium ore and samples of Autunite, Betafite Uranitite, to name just a few, sell for a few pounds. Provided the pieces are not too large and the radioactive emissions are below a set threshold they are legal to sell, buy and own. However, they can crumble and produce dust so it is wise to store them inside metal containers, well away from children and food preparation areas.


If you have any old clocks, watches compasses or aircraft instruments with glow in the dark luminous hands or dials, and they were made prior to the mid 1950s, then there is a very fair chance they will contain radium paint. This can produce a quite dramatic response, even from our most basic detectors.


Radium emits beta and some gamma particles and these can make excellent check sources. However, great care should be taken in the handling of these items, and never attempt to dismantle anything. Clocks and watches with boken or cracked glasses should also be given a very wide berth. That's because old radium paint can peel off or become flaky and liable to produce a fine dust. This can become airborne or get on to your hands or clothes and could represent a health hazard if inhaled or ingested. Indeed some of the workers involved in the manufacture of these articles suffered terrible ilnesses and death due to prolonged exposure and the practice of licking their brushes to obtain the  fine point needed to paint small, intricate items. Old aircraft instruments can be very radioactive, and a fair amount of vintage military equipment contained radioactive materials and components. Quite often they were not clearly labelled (or the labels fell off), so it is wise to keep a geiger counter handy if you tinker with old militaty surplus equipment.


Gas mantles, doped with radioactive Thorium (to increase luminosity) are no longer made in the UK but they are still being manufactured in other parts of the world, such as China and South America and they can be purchased from hardware shops and camping stores. The amount of radioactivity varies but some of the mantles we’ve tested have been highly reactive and capable of producing a quite dramatic response on all of our instruments. Again they should be handled with care – preferably left in their protective wrapping and stored in metal containers -- as they are made of cotton and liable to shed fine fibres or dust.


Radioactive gas mantles are now effectively illegal so you wont find them in your local DIY megastore or camping shop anymore. They sometimes turn up in long established local hardware stores that have have some old stock in

their storerooms, Sadly these venerable establishments are rapidly disappearing from out high streets but vintage gas mantles, usually still in their

original boxes, occasionally turn up in antique shops and at car boot sales. When installed and burnt the mantles produce a very fine dusty residue and if touched they crumble into tiny particles.In old victorian house there are often radioactive patches on walls and ceilings in areas where gas the lights used to be.


One of the most interesting sources of radioactive materials is old glass and porcelain, usually made prior to 1950, which can contain measurable amounts of uranium. The most famous examples are green-coloured Vaseline’ glass. Well known makers include the British company Bagley, which produced vast amounts of Vaseline glass items, which frequently turn up in antique fairs and car boot sales. The uranium content is typically well below 2% and it is safe to handle, though like any glass article it breaks easily and the real danger is from the sharp edges, rather than the radioactive content. The amount of radioactivity, and hence the degree of response varies enormously, from quite scary, to hardly anything.


Uranium is also a key ingredient in vividly coloured ‘Fiesta ware’ pottery. This was popular in the 1930s and 40s and the really radioactive stuff was mostly only sold in the US prior to WW II when the uranium content was reduced. Fiesta ware was produced in this country but it tends to be mostly non-radioactive, though pieces do turn up from time to time.


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