Ten things you should know about Finnish wood

Preservative-treated wood is frequently used in outdoor landscaping, but do you understand its processing, selection, and application? Are you familiar with Finnish wood, which is often mentioned? Let's take a look together!

01. What is Finnish wood?

After being treated with preservatives, wood is transformed into preservative-resistant wood that can prevent decay, mold, and termites. Preservative-treated wood made from Nordic red pine is often called Finnish wood.

02. Are there fake anti-corrosion woods?

Unscrupulous merchants use dyes and impregnation methods to pass off ordinary wood as "preservative-treated wood." Genuine preservative-treated wood only appears green or bluish-green because of the copper in the preservative.

03. What are some common types of wood used for preservative treatment?

Currently, the main preservative-treated wood species used in the domestic and international markets include Russian Scots pine, European red pine, American southern pine, and radiata pine. Let's take a look at the differences between the most common Scots pine preservative-treated wood and Finnish wood.

Finnish wood has physical properties and characteristics similar to Russian larch, but it is more stable and has a longer service life.

04. Does preservative-treated wood also have requirements regarding moisture content?

This is necessary because wood has the characteristic of shrinking when dry and swelling when wet, so preservative-treated wood also needs to be dried to control its moisture content.

Before preservation, the wood must be pre-dried to allow the preservative to fully penetrate the wood. After preservation, a second kiln drying is carried out to stabilize the wood's plasticity and reduce its moisture content to below 18%, making the wood less prone to cracking. The key is to allow the preservative to effectively combine with the wood cells and solidify, giving the wood excellent preservation properties and greatly extending its service life.

Do knots on the surface of wood affect the quality of preservative-treated wood?

Knots, cracks, and warping on the surface of wood can affect its preservative properties. Defects such as knots not only affect the appearance of the wood but are also important channels for fungi and insects to invade it.

06. How to judge whether the preservative-treated wood is qualified from its appearance?

The smoothness and color uniformity of the surface of preservative-treated wood can reflect the effectiveness of the preservative treatment. The smoother the surface and the more uniform the color, the better the treatment effect.

07. How should we choose different grades of preservative-treated wood?

If used outdoors but not in contact with the ground, the preservative-treated wood should have a drug loading of 4 kg/m³ or more; if used outdoors in contact with the ground or immersed in fresh water, the preservative-treated wood should have a drug loading of 9.6 kg/m³ or more.

08. What is preservative penetration?

Preservative penetration refers to the depth to which the preservative penetrates the wood. The greater the penetration depth, the less likely the protected pressure-treated wood is to be damaged. Taking CCA-C treated preservative-treated wood as an example, if it is used outdoors but not in contact with the ground, the penetration depth should be greater than or equal to 85%; if it is used outdoors in contact with the ground or immersed in fresh water, the penetration depth should be greater than or equal to 95%.

Let's take a look at how to calculate penetration.

9. What are the common sizes of preservative-treated wood?

10. How should preservative-treated wood be installed?

Preservative-treated wood can be installed according to its intended use. Common installation methods include: overlapping, snap-fit, grille, and slat installation.