Wet Storage - Basics
Experiences after the big storms in 1990
("Wiebke und Vivian") and 1999 ("Lothar") showed that wet
conservation is the only timber conservation method which is – if carried out
properly – suited to store large amounts of timber over several years (up to
4-5 years for softwood) without deterioration of quality.
method is based on permanently keeping wood moisture on a high level by
artificial irrigation. The wood pores remain filled with water, air can not get
inside the wood. Wood destroying fungi and insects can not live without oxygen.
- Only timber conservation method
which is – if carried out properly – suited to store large amounts of timber
over several years without deterioration of quality;
- Large quantities of timber can
be stored in one place;
- Today, a great deal of
information and know-how on wet storage technique is available;
storage as a storage method is accepted and approved by the better part of the
- Investment costs can be very high, depending on site properties and
- Stains can develop in the sap wood. The discolouration is caused by
tannins, which can enter the wood while dissolved in water during irrigation
and later during the drying process;
- Armillaria infestation has been found in wet storage, even where
irrigation quality was high;
- When further processing wood from wet storage, uneven absorption of
paint and glazing has occurred;
control of the technical assets is absolutely necessary. Malfunction of the
irrigation system of several hours can already put success at risk.
- Storage location
- The site should have good
transport connexion and access roads which support high loads.
Sufficient water supply (esp. in summer!) is obligatory. Power supply
has to be ensured where electric pumps are used.
- Water extraction
- At least 1 l/sec irrigation
is required to safely conserve 1,000 cubic metres roundwood. This means
a minimum hourly requirement of 3.6 cubic metres of water per 1,000
cubic metres roundwood (max. height of stacks 4 metres, which means no
more than 35 cubic metres of timber per running metre!).
- The logs are piled with the
butt end facing the road, and at right angles with the road. Height of
stacks may not exceed 4 metres. Logs should be sorted by length and
- Timber quality
- Only best quality timber is
suited, low-grade timber must not be put in wet storage. Success can
only be guaranteed if timber is assorted in a strictly quality oriented
- Daily control of the site/ the
- Coordination of primary conversion and transport capacities: as little
time as possible should pass between conversion and irrigation (no longer than
two weeks in cold, humid weather, immediate start of irrigation in dry, hot
- Sufficient transport capacities.
- Delayed start of irrigation (not before site is completely stacked) if partial
irrigation is not possible.
administrative approval for operating wet storage sites, strict licensing
requirements and conditions.