Your Gas Stove Is Turning Your Pots Black
Are your frying pans, saucepans and other cooking implements being left black after they've been used for cooking or reheating food on your gas hob? This is not normal. There are two potential causes for this problem and they are closely linked: they both impact the quality of the flame by producing a bad mixture of gas and air at the burner. The blackness left behind on your pans is actually soot resulting from incomplete combustion due to a lack of oxygen.
THE POSSIBLE CAUSES FOR THIS ISSUE:
WARNING
Before doing any work on your appliance, make absolutely sure you disconnect it from the power supply and switch the gas supply off at the valve.
There is a risk of receiving an electric shock.
Wear suitable protective gloves if you need to dismantle anything.
There is a risk of getting cut or injured.
The air supply is not correctly adjusted
The first possible explanation for why the flames on your hob are blackening your pans and other cooking implements is that the amount of air arriving at the burner is not properly adjusted. Gas hobs on which the air supply to the burners can be adjusted have an air adjustment collar fitted between the jet and the burner. To adjust the air supply, you vary the distance between the jet and the air collar (shown in grey in the image). This allows you to make the air supply hole either larger or smaller, thus enabling you to vary the air flow rate.
If saucepans and frying pans, etc., are being left blackened, the cause will be a lack of air. When this is the case, a tall, soft, unstable, smoke-producing flame is produced, which in the worst cases will be orangish to yellow in colour. Correctly adjust the air flow rate to increase the amount of air delivered and obtain a good quality flame.
The gas nozzles (jets) are not the right kind
The flames on your gas hob can also blacken saucepans and frying pans, etc., if the jets fitted are not the right kind for the type of gas you're using.
Though the air supply itself isn't the specific cause in this case, the resulting problem is to all intents and purposes the same as with the previous issue. Because the jets are the wrong kind, they supply too much gas to the burner, which produces a bad gas-air mixture, causing your pans to blacken. As with the previous issue, the flame produced will be tall, soft and unstable, and tend to be orange or yellow in colour.
If this is the issue you're experiencing, it's because your jets are designed for use with natural gas (domestic gas) and therefore have too large a diameter hole. You will therefore need to replace them with jets designed for use with bottled butane or propane gas, i.e. jets with smaller diameter holes that deliver less gas to the burner.
Note: to tell whether you have a good flame that won't blacken your pans, look at its consistency: it should be properly stable. It should also produce very little noise and not give off any gas or smoke. And as far as colour is concerned, a good quality flame will be vivid blue at its core.