How to Repurpose Used Cooking Oil into Environmentally Friendly Candles

How to Repurpose Used Cooking Oil into Environmentally Friendly Candles


Recycling used cooking oil into candles is a great way to repurpose a waste product into something useful and environmentally friendly. Candles made from used cooking oil, sometimes called “bio-diesel candles”, provide an alternative to paraffin wax candles. Paraffin wax is a byproduct of petroleum refining, while bio-diesel candles reuse waste vegetable oil that would otherwise be discarded. Converting used cooking oil into candles keeps it out of landfills and waterways where it can cause environmental damage.

In this comprehensive guide, I will walk through the entire process of collecting used cooking oil, preparing it for reuse, and turning it into homemade candles.

Collecting and Storing Used Cooking Oil

The first step is gathering used cooking oil that would otherwise be thrown out. Here are some tips for collecting and storing oil for candle making:

Sources of Used Cooking Oil

  • Restaurants and commercial kitchens – Ask locally owned restaurants if they would donate their waste fryer oil. This is often the easiest way to get large quantities of used oil for free.

  • Household cooking oil – Save oil from deep frying and sautéing at home. Strain out any food debris.

  • Food manufacturing facilities – Factories that produce fried snacks or other oily foods may give away their waste oil.

Storage Containers

  • Store used oil in clean, sealable containers like glass jars or plastic jugs. Make sure they do not contain water or food scraps.

  • Avoid reactive metals like aluminum, copper, and zinc, which can interact with fatty acids in the oil.

  • Prevent light exposure by using dark containers or keeping in a dark area. Light can speed oil degradation.

  • Label each container with the type of oil and date collected.

Maintaining Quality

  • Strain oil through a fine mesh sieve or cheesecloth to remove food particles.

  • Refrigerate or freeze oil to prevent it from going rancid over time. Rancid oil will not work well for candle making.

  • Avoid mixing oil types like vegetable and olive oil. Different oils have different properties.

Preparing Used Cooking Oil for Candles

Before making candles, the used cooking oil needs to be cleaned and treated. Here is an overview of oil preparation:


  • Heat oil to 200°F (93°C) – Heating helps separate oil from residual water and food debris.

  • Strain through cheesecloth – Pour hot oil through layered cheesecloth to filter out particles.

  • Let oil cool and settle – Particles will sink to the bottom, then oil can be poured off the top.

  • Repeat straining – Strain a second time through a coffee filter for clearer oil.


  • Optional step – Remove phospholipids using hot water or acid such as citric acid.

  • Helps prevent smoking – Phospholipids can burn and create smoke.


  • Use sodium sulfate – Mix in 1 tsp per cup of oil and let sit overnight.

  • Absorbs water – The sodium sulfate will turn into a solid clump, which can then be filtered out.


  • Add essential oils – Stir in a few drops of essential oils for desired fragrance.

  • Common scents – Lavender, lemon, vanilla, jasmine, rose, peppermint.

Making Candles from Recycled Cooking Oil

Once used cooking oil is collected, cleaned, and treated, it’s ready to be transformed into candles using one of these methods:

Container Candle Method

Best for beginners

Supplies Needed:

  • Cleaned used cooking oil
  • Wick (pre-tabbed or use wick stickum)
  • Candle container
  • Double boiler


  1. Set up a double boiler to gently heat oil to 180-200°F.

  2. Add fragrance if desired.

  3. Carefully pour hot oil into container holding wick.

  4. Allow to fully cool and solidify before burning.

Mold Candle Method

Allows custom shapes

Supplies Needed:

  • Cleaned used cooking oil
  • Wick (pre-tabbed or use wick stickum)
  • Candle mold
  • Double boiler


  1. Set up double boiler and heat oil to 180-200°F.

  2. Prepare wick in mold by adhering to bottom with wax or stickum.

  3. Carefully pour hot oil into mold.

  4. Let fully cool and solidify for 24-48 hours before removing mold.

Rolled Candle Method

Creates large pillar candles

Supplies Needed:

  • Cleaned used cooking oil
  • Wick (pre-tabbed or use wick stickum)
  • Parchment paper
  • Double boiler
  • Cooling rack


  1. Heat oil to 180-200°F in double boiler.

  2. Soak wick in oil, then lay flat on parchment paper.

  3. Slowly pour oil over wick along entire length.

  4. Cool completely on rack before gently rolling into pillar candle.


  • Add beeswax – Makes brittle oil more pliable if candle doesn’t harden properly. Start with 10%.

  • Avoid drafts & temperature changes – Cool candles slowly to prevent cracking or shrinkage.

  • Use taller containers – Deeper candles help support a rolled pillar shape.

Benefits of Recycled Oil Candles

Converting used cooking oil into candles offers many advantages:

  • Sustainable – Repurposes waste instead of using new resources

  • Economical – Used oil is free, only need basic supplies

  • Environmentally-friendly – Keeps oil out of landfills and waterways

  • Odorless – Treatment removes cooking odors

  • Customizable – Fragrances and shapes as desired

  • Satisfaction – Provides a sense of purpose from recycling

So if you want to reduce waste while making something beautiful and useful, try your hand at crafting candles from recycled cooking oil! With some simple preparation, used oil can be upcycled into lovely glowing lights.