Votive candles are made from different types of waxes including paraffin, soy wax or beeswax. The most effective shielding materials are water, or hydrocarbons like polyethylene or paraffin wax. It is soluble in propylene glycol, paraffin oil, and kerosene. Microcrystalline waxes are excellent materials to use when modifying the crystalline properties of paraffin wax. It is made by soaking cotton threads in a starch and paraffin wax solution. Hydrocarbon glide waxes, based on paraffin are common for recreational use. Phase change materials such as paraffin wax and Glauber's salt are another thermal storage medium. A simple example is a copper mesh immersed in paraffin wax. Such crayons are usually approximately in length and made mostly of paraffin wax. Many oils are oligomeric, such as liquid paraffin. This wick is soaked in a flammable liquid, usually paraffin (kerosene). This version is sold covered in cloth and paraffin wax. They had already tried other fuels in prior iterations including cotton, paraffin wax and wood. It was later discovered that this radiation could knock hydrogen atoms out of paraffin wax. His machine burned petrol and/or paraffin (kerosene) as fuel.