What oil to use
There are many different types of fuel, from kerosene to paraffin and coloured to perfumed. Besides that, there is the lingual difference in what type of oil it is. Take for example the Dutch “petroleum” which in the large parts of the world would ruin an oil lamp, because it’s crude oil or would give a large explosion.
Let’s start at the lingual difference.
The DHR oil lamps work best on purified, clear kerosene. But here comes the tricky part, what is kerosene and what is lamp oil. The kerosene we advise, is a clear, purified and odourless kerosene, not to be confused with Jet type Kerosene. In Dutch this is called purified Petroleum. But in the rest of the world Petroleum can be gasoline as well as a crude oil.
Lamp oil on the other hand has two types, one is a kerosene based, the other is a paraffin based lamp oil. The kerosene based lamp oil can be purified or not. The purified kerosene can be used in- and outdoors, the non purified kerosene is only suitable to use outdoors, for example in garden torches. Because of the toxic gasses it releases when burning the impurities in the kerosene. The paraffin based lamp oil is not advised by DHR. Paraffin, like kerosene, is an oil distillate. But paraffin isn’t very much liquid. To make it into an oil, solvents are added to make it more liquid.
The flashpoint of fuel.
Every fuel has a flashpoint, this is not the boiling point nor the self igniting point. The flashpoint is the lowest temperature a chemical needs to give enough damp that it ignites when it comes into contact with an ignition source.
The lower the temperature, the more flammable it is. Gasoline for example has a flashpoint around minus 21° C. Paraffin is not a liquid, but a crystal. To make it a liquid it is dissolved and therefore it is available in different flashpoints, based on the solvent used. Use only oils with a flashpoint around 70°C/158°F.
What happens when the flashpoint is to low or to high.
When a flashpoint is to low, gasses will build up in the reservoir because of the heat coming off the burner. This can cause an explosion and therefore use only recommended fuels for oil lamps.
When a flash point is to high, a higher temperature is needed. Understanding the triangle of fire, where a fire is in balance with oxygen, fuel and heat, you can see that the fuel needs more heat to burn it. More heat means higher flames and thus more air. Therefore the flame is going to consume the wick as an easy source of fuel. So you will not only keep burning wicks up very fast, the oil lamp will give off nasty odours (of the burning wick) and a lot of sooth.
Coloured and/or perfumed lamp oils and their use.
The coloured or perfumed oils are best used in oil lamps that have a fibreglass wick. The capillary functioning of the wick makes sure the oil is transported up fast enough. And, because of their higher flashpoint, you don’t burn your wick down all the time.
Kerosene v.s. paraffin
Purified kerosene is preferred for the DHR lanterns because of its lack of odour and excellent flashpoint. Paraffin can be used where purified kerosene is not widely available. However, it has some disadvantages in comparison to the kerosene. There are de-odorized paraffin lamp oils, but none the less they give some sort of an odour. Then there is the fact that the solvent in the paraffin oil will eventually evaporate when the lamp isn’t used for some time. The paraffin in the wick and burner mechanism will crystallize and eventually the mechanism gets stuck or the wick can’t bring up enough oil. If you do choose to use paraffin there are a few things to bear in mind.
At first, when you stop burning the lamp regularly, take out the oil en clean the wick with a cloth to remove as much oil as possible. Even better would be to take the wick out and replace it with a new one. If the mechanism gets stuck it can be boiled clean in an old pan with water. It takes a few hours and can best be done outside because of the smell it releases.
If you found an old oil lamp or you are not sure whether you used paraffin oil or not, take a look at the wicks colour. A green or greenish colour indicates that paraffin is solidified in the wick.