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 particle of material emits alpha and low energy gamma particles, which is mostly absorbed by the metal casing surrounding the detector module, though they can be detected using a highly sensitive ‘Pancake’ probe, like  the one we sell with our Dual Probe CDV-700 Geiger counter.

Another household product that emits enough low-level radioactivity to be picked up by our most sensitive instruments is ‘Lo Salt’, the low sodium alternative to common table salt. The radioactivity, in the form of alpha particles comes from the Potassium Chloride it contains. Brazil nuts and cat litter are known low-level sources and step outside your home into the street and there’s a fair chance that the kerbstones or road surfaces are gently radiating. They are often made of  granite.and this can be surprisingly radioactive. In some cases there can be enough of it to get a reaction from a basic dosimeter like our DRSB-01 .

In some parts of the UK (notably Cornwall, Devon and Scotland), where the bedrock contains substantial quantities of granite you can find 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, are  readily available for a few pounds. Provided the pieces are small 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 keep them well away from children, food preparation areas and they should be stored inside a metal container

If you have any old clocks, watches compasses or instruments with 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, and 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. Care should be taken in the handling of these items, though, and do not try to dismantle them as the radium paint is often old and flaky and liable to produce dust, which can become airborne and could represent a potential health hazard if inhaled or ingested. Indeed some of the workers involved in the manufacture of these articles suffered terrible ilnesses and even death due to the practice of licking their brushes to obtain a fine point in order to paint 

small and intricate items.

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 in all of our detectors. Again they should be handled with care – preferably left in their protective wrapping -- as they are made of cotton and liable to shed fine fibres or dust. When installed and burnt the mantles produce a find residue and if touched they crumble into fine particles and in old victorian house there are often radioactive patches on walls and ceilings in areas where gas 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.