Bio‑based Impregnations (New Generation)

Bio‑based impregnations are an emerging category in wood protection. While traditional impregnations rely on fossil‑based chemicals, synthetic resins or metal compounds, bio‑based products use plant oils, natural resins, biopolymers and modified bio‑molecules. This new generation combines sustainability with impressive technical performance — making it suitable for modern architecture, restoration work and circular construction.

1. What Are Bio‑based Impregnations?

Bio‑based impregnations are wood protection products whose active components originate from:

• plant oils (linseed, tung, soybean, castor)

• natural resins (pine resin, damar, shellac)

• biopolymers (cellulose derivatives, lignin extracts)

• modified fatty acids

• bio‑based esters and polyesters

They are used to:

• reduce moisture uptake

• inhibit fungal growth

• slow UV‑induced discolouration

• stabilise the wood

• enhance appearance

2. Why a “New Generation”?

Modern bio‑based impregnations differ significantly from traditional linseed oil or natural resins. They are:

• chemically modified for improved durability

• faster drying

• deeper penetrating

• less prone to yellowing

• more resistant to leaching

• compatible with both modern and historic wood

This makes them suitable for a wide range of applications.

3. Types of Bio‑based Impregnations

1. Modified Plant Oils

Examples:

• stand oil

• alkyd oils based on plant fatty acids

• tung‑oil esters

Properties:

• deep penetration

• water repellency

• good UV resistance

• ideal for cladding and exterior joinery

2. Biopolymer Impregnations

Based on:

• cellulose esters

• lignin derivatives

• natural polyesters

Advantages:

• excellent vapour permeability

• low viscosity → deep penetration

• environmentally friendly

3. Plant Resin Emulsions

Examples:

• pine resin dispersions

• damar resin emulsions

Applications:

• decorative finishes

• light protection

• ideal for interior use and restoration

4. Bio‑based Hydrophobing Agents

Based on:

• modified fatty acids

• bio‑silane hybrids

Properties:

• highly water‑repellent

• transparent

• non‑film‑forming

• excellent for façade timber

4. Advantages of Bio‑based Impregnations

1. Sustainable and environmentally friendly

• renewable raw materials

• low carbon footprint

• fewer toxic components

2. Compatible with historic timber

• no aggressive solvents

• no vapour‑tight film

• reversible or semi‑reversible

3. Aesthetic benefits

• natural appearance

• warm tones

• no plastic‑like sheen

4. Strong technical performance

• good water repellency

• improved UV resistance

• reduced leaching compared to classic oils

5. Limitations and Considerations

1. Less suitable for extreme moisture exposure

Such as:

• ground contact

• permanently wet zones

• poorly ventilated structures

2. Regular maintenance required

Even improved bio‑products remain maintenance coatings.

3. Variable quality

Cheaper products may:

• weather quickly

• remain sticky

• offer insufficient protection

4. Not always fungicidal

Some require additional additives for biological resistance.

6. Practical Applications

1. Façade cladding

Bio‑based impregnations work well on:

• thermally modified wood

• larch, Douglas fir, cedar

• Accoya and Kebony (as UV protection)

2. Exterior joinery

Modified oils and bio‑silane hybrids perform particularly well.

3. Interior and restoration work

Natural resins and oils are ideal for:

• historic beams

• floors

• panelling

• furniture

4. Garden and landscape structures

Suitable for:

• pergolas

• fences

• outdoor furniture

with proper maintenance.

7. Comparison: Bio‑based vs. Traditional Impregnation

Property	Bio‑based	Traditional
Durability	High (product‑dependent)	Variable
Vapour permeability	Excellent	Often moderate
Environmental impact	Low	Medium to high
UV resistance	Good (with additives)	Good to excellent
Leaching	Low to medium	Medium to high
Maintenance	Regular	Regular
Historic compatibility	Excellent	Sometimes problematic

8. Best Practices for Application

• wood must be dry (< 18% moisture)

• always apply top to bottom

• thin layers → better penetration

• treat end grain generously

• avoid application in direct sunlight

• test on a small area first

9. Summary

Bio‑based impregnations represent an innovative and sustainable step forward in wood protection. They combine:

• natural raw materials

• strong technical performance

• compatibility with both new and historic wood

• an aesthetically pleasing finish

They are not ideal for every situation, but in many applications they offer a high‑performance, environmentally responsible alternative to traditional impregnations.