Boiled Linseed Oil on Rusty Metal – a Good Idea? Or Not?

Is boiled linseed oil good for metal? Does linseed remove rust? What are linseed oil and hydrogen peroxide? This article is about whether or not it is a good idea to use boiled linseed oil to remove rust on metal.

Iron starts to rust when exposed to air and water, which is called oxidation. The rusting process is accelerated if the iron has been overheated or if it comes in contact with salt water. Rust can be removed by sanding, grinding, or wire brushing the surface, but these are temporary solutions that can leave rust behind and still damage the metal itself.

Boiled linseed oil dries faster than raw linseed oil, but it is also more acidic. Boiled linseed oil is a by-product of the safflower oil industry and is therefore also known as “safflower oil”, “hulls dryer” or “cold-pressed”.

Safflower seeds are pressed to extract the raw linseed oil, and then the remaining material is solvent processed to extract the second batch of oil which is called boiled linseed oil. Solvent processing involves the use of toxic solvents and should be avoided whenever possible.

Boiled Linseed Oil – Product Focus

Boiled linseed oil is the most commonly used oil for the restoration of old or damaged wood. The reason for boiled linseed oil’s versatility lies in its ability to be used as a surface treatment or a penetrating treatment.

The main difference between the two treatments is the amount of surface penetration that is desired. As surface treatments, boiled linseed oils have very little penetration into the wood and tend to fill in only small cracks and pores. As a penetrating treatment, BLO has a significant penetration into the wood and can result in a very bumpy and pitted finish.

Boiled linseed oils can also be applied to metal surfaces for protection or for creating a finish that is resistant to corrosion. They can be used to fix small areas of rust, such as on the outside of cast iron sinks that have rusted through.

Uses of Boiled Linseed Oil

Boiled linseed oil is used in various ways, the most common being as a wood finish.

Others include:

  1. Linseed oil and turps mixture are used for the removal of rust from boilers and other metal parts.
  2. Boiled linseed oil and soap are used in applications where rust needs to be prevented, such as frying pans where the saucepans are much more vulnerable to rust than the food they contain.
  3. Boiled linseed oil, applied by spraying onto corroding live trees in an attempt to stop them from falling.

It is also used as a part of the sealer/coating used on metal food cans. These cans are known as “enamel” and the paint is called a “lacquer” and the whole can is an “enameled steel”. It’s important to note that boiled linseed oil does not protect the enamel coating from corrosion. It is simply shellac or varnish that coats the metal’s surface.

Does Boiled Linseed Oil Remove Rust?

Boiled linseed oil is a good rust preventive, which is why it is used in the durability test applications mentioned above. The problem with boiled linseed oil for removing rust from metal surfaces is that it does not chemically cauterize rust and therefore penetrating rust pits remains possible. To remove rust completely, the rust must be chemically removed (e.g., by the use of sodium hydroxide).

To avoid corrosion, for example in the above-mentioned case of food cans, it is important to make sure that the boiled linseed oil does not get into any of the smaller crevices of the enamel (which is called “pitting”) but instead remains on the surface.

So, the BLO doesn’t remove rust but it can protect the metal surface of forming rust after application of the oil. It creates special film that prevents water and air from coming into contact with the metal surface.

How to Apply Boiled Linseed Oil

Boiled linseed oil is applied with a rag as paint. Apply the oil as thinly as possible and wait for it to dry before adding another coat if required. On the surface of the metal, use an oil-free rag and rub it against the metal, being careful not to get it into any of the small crevices in an attempt to remove it. It is important that boiling linseed oil does not get into any of these crevices as this could lead to corrosion.

If you need to remove rust from a surface, the simplest way is with a scraper (i.e., a wire wheel that can be pulled across the surface). Gloves should be worn at all times when handling boiled linseed oil as it can cause burns.

Removing Boiled Linseed Oil

Use sandpaper to remove the oil from the surface of the metal in a similar way to how it is removed from the wood. From time to time, the surface will seem to have a little blue film on it due to the oxidation process that has begun. Do not sand this blue film off, as it is part of the coating and thus it protects your metal from rust completely.

When removing boiled linseed oil from steel surfaces, use a wire wheel with a wire/steel tip.

Sometimes, removing this oil completely is impossible without destroying the surface of the object. For example, to completely remove BLO from wood, you will need to take off some part of the surface with an appropriate instrument.

The Dried-Out Finish

If a coat of paint is applied to some surface and it dries out before it is completely dry, the surface can become difficult to finish. To get around this problem, apply a wet rag of boiled linseed oil (or raw linseed oil if you want) on top of the dried-out paint. The additional layer will act as a barrier between the surface and the air, thus slowing down any further drying process and ultimately allowing you to finish properly in a shorter amount of time.

Letting BLO dry properly is a key to success. Before applying the oil to your project, always read instructions and try to create optimal conditions for drying. Otherwise, the project may go in the wrong way and BLO will only disturb you from getting optimal results in the end.

Health and Safety

Boiled linseed oil has a very strong smell and is not recommended for indoor use as it can cause health problems. People with asthma are particularly at risk of a reaction. Choosing a well-ventilated area is also important.

Boiled linseed oil contains oxalic acid, which, if regularly applied to the skin, can cause long-term damage such as the formation of hard dry scales over the skin. It can also cause irritation and itchiness in some cases. If you get burnt by boiled linseed oil then this can cause serious damage to the skin for example if you get it in your eyes.

Boiled linseed oil is also very acidic, which can be a problem if not stored correctly and used often enough. Some people are allergic to acid and should not apply it to their skin.

BLO also contains metals such as iron, aluminum, zinc, and barium. It may also be toxic in large doses.


Boiled linseed oil is an excellent product to use for a wide variety of purposes. If used properly it can help you achieve many different looks and finishes on a variety of materials, however, the right methods must be used to get the best result as well as being aware of the side effects or problems that may occur.

BLO can be applied in several ways which means it allows for a huge amount of flexibility in applications. Some of the best qualities of boiled linseed oil are that it is not affected by water, that it minimizes shrinkage when drying, and that it can be easily removed after application.

Although boiled linseed oil is mostly used for wood restoration, it can be applied to metal surfaces as well and has some other uses. It is a very versatile product that works well on many different materials but can also be dangerous if not handled carefully.

Boiled linseed oil is the most commonly used oil for the restoration of old or damaged wood. The reason for boiled linseed oil’s versatility lies in its ability to be used as a surface treatment or a penetrating treatment. The main difference between the two treatments is the amount of surface penetration that is desired.

Overall boiled linseed oil is an excellent product to use for many different purposes, but if used properly it will help you to achieve many different looks and finishes with ease.