What is deck soap?

Deck soap is a soap that is designed to clean and care for outdoor wood, especially decks and patios. Unlike regular cleaning soap, deck soap is usually clearly over-greased, which means that it not only dissolves dirt but also helps the wood maintain its natural fullness and resilience over time.

It's a method that feels very Swedish for a reason. For generations, soap has been used on wood to clean without wearing down the material, especially in environments where weather, moisture and seasons place high demands. Deck soap builds on that tradition, but is adapted for modern decks and today's use.

Trallsapa in brief

Laundromat soap is a soft, oily soap based on saponified vegetable oils. It is rich in fat and therefore works differently than regular household soap:

• It cleans by lifting dirt from the surface of the wood.
• It is gentle on the wood fibers.
• It leaves a mild caring effect that makes the surface easier to keep clean.

The result is often a deck that looks naturally fresh, rather than harshly or chemically cleaned.

There are many variants on the market and they can be based on different raw materials – for example, tall oil, linseed oil, tallow or purified recycled vegetable oils. It may sound like the base oil is the whole secret, but in practice the end products are often more equivalent than you think.

The differences are usually noticeable in scent, color and consistency, while the basic function is the same: a good, over-greased decking soap cleans gently and leaves a mild caring effect on the surface. For wood, the method of application, mixing and regular maintenance almost always mean more than which oil is on the label.

How soap is formed

Soap is created through a simple and natural chemical process where vegetable oil reacts with lye in water. The process is called saponification and has been used for hundreds of years to create an effective cleaning agent without synthetic additives.

When the reaction is complete, the oil has been converted into a mild cleaning substance that breaks down naturally in the environment and works particularly well with wood and other organic materials.

In finished deck soap there are therefore only three basic ingredients:

• Saponified vegetable oil
• Water
• A controlled amount of residual fat in high-fat varieties

It is precisely this simple composition that makes deck soap an environmentally friendly alternative. It contains no synthetic surfactants, solvents or microplastics and leaves no harmful residues in soil or water.

The extra greasing also means that decking soap not only cleans, but also cares for the wood. The grease that remains on the surface reduces drying out and the need for harsher treatments, which in itself contributes to more sustainable maintenance over time.

Why greasing is important for decking

An overly greasy decking soap contains more grease than is required for the actual cleaning. This excess grease remains partially on the surface of the wood after washing and contributes to:

• The wood does not dry out.
• The surface becomes less brittle and more resistant.
• Dirt and pollen become more difficult to adhere to.

This is a crucial difference compared to many other cleaning products, which instead dissolve grease and leave the wood completely unprotected.

What oils are used in deck soap?

The type of oil used affects both the properties and character of the finished soap. Historically, many different fats have been used, primarily depending on what was available.

In the subsistence farming community, animal fat was common in soap making, simply because it was a by-product that was available. Over time, production has shifted to vegetable oils, which provide a more consistent quality and are better suited to modern deck care.

Common base oils in modern soap making are:

• Pine oil, often used in traditional green soap
• Linseed oil, which yields linseed oil soap
• Vegetable oils such as rapeseed and corn oil

In some cases, purified and recycled oil from the food industry, for example from commercial kitchens and fryers, is also used. The oil is purified and filtered before being saponified, making soap a product well suited to circular flows where raw materials are used rather than consumed unnecessarily.

What does KLARA's deck soap contain?

KLARA's decking soap is based on a combination of Swedish rapeseed oil and linseed oil. Together they create a stable, mild and highly greasy soap that is particularly suitable for decking and wooden surfaces outdoors in Nordic climates.

The rapeseed oil contributes to a smooth and controlled cleaning, while the linseed oil adds deeper re-greasing properties – the same type of natural oils that have made traditional linseed oil soap appreciated for wood for generations. The result is a decking soap that cleans gently while helping the wood to maintain its natural structure, fullness and resilience over time.

Using rapeseed and linseed oil is also a conscious choice from a sustainability perspective. Both are vegetable, renewable raw materials that are well suited for soap making and provide a product free of synthetic surfactants, solvents and unnecessary additives.

In addition to the super-greased base, KLARA's decking soap also contains a unique addition of beeswax . Beeswax is chosen to help the wooden surface resist moisture and dirt over time, without creating dense layers or changing the natural feel of the wood. The ambition is a more durable, even and long-lasting result than with traditional decking soap.

See KLARA decking soap with beeswax .

What makes deck soap different from regular soap?

All soaps can clean, but not all are created for the same job. Regular soap is usually designed for indoor cleaning and household surfaces. Deck soap is developed for outdoor wood, where sun, rain, moisture and temperature changes place completely different demands on the surface.

The super-fatty composition means that deck soap provides a more long-term care effect. Instead of just dissolving dirt, it adds grease that helps the wood resist drying out and wear over time.

If you want to see the differences clearly described, there is more here:

• Practical questions about deck soap
• Soap vs oil – what is best for decking?

What can you use deck soap for?

Decking soap is mainly used on:

• Wooden decking and balconies
• Stairs and steps
• Railings and posts
• Outdoor furniture made of untreated or previously soaped wood

The method does not require any special machines. Water, a brush and the right mixture will go a long way. If you want to use the same method on more surfaces, there is a comprehensive guide here: Can you soap balcony railings, stairs and outdoor furniture? .

How do you use deck soap in practice?

If you want the entire workflow in one place, from preparation to finishing, start here: How to scrub decking – step by step .

An evenly greyed decking is not a problem in itself, but often a natural and beautiful result of long-term soaping. However, if the decking feels dry, rough, uneven or has heavy algae growth after several years without maintenance, a more thoughtful start may be needed. In that case, there is a special guide here: Saving a decking that has not been maintained for several years .

A brief summary

Decking soap is a gentle and effective way to clean and care for decking. It cleans without tearing up the fibers and, thanks to its super-fatty composition, can help the wood stay stable, resistant and beautiful over time. It is a method that suits the Nordic climate and works just as well for the first cleaning of spring as for ongoing maintenance during the season.

If you want to plan maintenance over the year, you can continue here: How often should you soap your decking? A simple annual plan .