Graying – The natural patina of wood outdoors
Definition: Graying describes the natural color change of the wood surface in exterior areas. Lignin is broken down and washed out by UV radiation, moisture and oxygen, resulting in a silvery-grey color. This optical process does not affect the durability of the wood and is often appreciated as a desired patina.
Greying describes the natural color change of wood outdoors. UV radiation, moisture and oxygen cause the surface to turn silvery gray. What used to be considered a defect is now appreciated as a high-quality patina – used deliberately or treated specifically.
The natural graying of wood – a noble patina
Why wood greys – a natural process
Wood graying is a completely natural process. UV radiation breaks down the lignin contained in the wood on the surface. Rain and dew wash out these components so that the light cellulose fibers become visible. According to studies by Holz Forschung Austria, this process is purely optical and has no influence on the load-bearing capacity or durability of the wood. Especially decking woodfacades or wooden outdoor furniture are affected by this. Depending on the type of wood (e.g. larch, Douglas fir, teak), the graying process varies in speed and intensity.
Silver-grey patina – deliberate aesthetics
Uniform graying is often deliberately sought today. Architects and building owners appreciate the calm, elegant appearance of a silvery, shimmering wood surface. Uniform weathering is crucial for a harmonious appearance. Unprotected areas or waterlogging lead to stains. One solution is pre-greying, in which special oils or glazes visually anticipate the natural process. This creates a uniform appearance right from the start – particularly popular with decking boards and facades.
Refresh or consciously accept graying
The graying of wood can be treated in a targeted manner – at least temporarily. Oxalic acid is often used for graying, which chemically dissolves the gray patina layer and visibly brightens the surface. However, only subsequent oiling brings back the warm, original wood color. wood color the warm, original wood color. Alternatively, the floorboards can also be sanded down. It is important to note that these measures only have a temporary effect. UV radiation, rain and temperature fluctuations will cause the natural graying to set in again. Anyone who uses wood outdoors – whether on a terrace, furniture or façades – should therefore make a conscious decision between regular maintenance or a permanent natural patina that ages gracefully.
The before and after effect
Sources:
dataholz.eu – Vergrauung Terrasse,
Holz Forschung Austria (HFA Austria),
Holz vom Fach – Verfärbung bei Terrassenholz,
Baunetzwissen – Vorvergrauung
Frequently asked questions about the graying of wood
Wood greys outdoors due to the natural effects of UV radiation, moisture (rain, dew) and oxygen. UV light breaks down the lignin contained in the wood on the surface, which is then washed out by moisture. What remains are the lighter cellulose fibers, which produce the typical silvery-grey hue.
No, graying is a purely visual process and has no negative impact on the technical durability, stability or load-bearing capacity of the wood. It is a superficial change that does not damage the substance of the material.
It is not possible to completely and permanently prevent graying in outdoor areas without chemical treatment or opaque coatings, as this is a natural process. However, graying can be temporarily removed with special graying agents (e.g. based on oxalic acid) and the original wood color can be restored by subsequent oiling. However, these measures must be repeated regularly.
Pre-greying is a technique in which wood is given an artificial silvery-grey hue using special oils or glazes before installation. This is used to achieve a uniform, grayed appearance from the outset and to avoid uneven natural graying processes.
Teak decking planks finger-jointed 95mm
from 13,25 €
Teak decking boards, FSC 100%
Price from: € 130 per m2, resistance class: 1
Advantages: ✓ long teak planks up to 390cm long ✓ best durability and dimensional stability ✓ lowest risk of cracking and splintering
Disadvantages: ✗ Changing grain due to finger-jointing
Tip: Optical transitions of the finger-jointing fade when exposed to weathering.
14,95 €
from 24,95 €
