Log Storage - Wood Yard

Woodyard - Log storage

The main purpose of a wood yard is;

• To receive logs, wood residues and chips
• Debark logs and residues
• chip logs residues
• to store bark and chips

Raw materials for paper production

• small Diameter logs (approx.: 8cm to 40cm) from forest thinning's (coppicing)
• Sawmill residues sawdust, chips, unusable wood scraps

Traditionally used woods

• Softwoods typically spruce and pine (great fiber morphology)
• Hardwoods like birch, poplar beech, and eucalyptus

Wood handling

Separate processing or different species of wood, the mixing of wood species should be avoided.

Log storage

·         Orderly stacks

·         Piles of wood (need to be sprayed with water)

·         Storage in water (uniform moisture content)

·         Wood chips can be stored in silos or open-air storage piles

Logs for wood pulping

Usually,  cut down to 1m lengths and diameters of (10cm to 35cm) the moisture content ideally should be  > than 35% for optimal fiber removal

Quality control parameters

·         Amount (eg weight)

·         Moisture

·         Contamination

·         Shape (straight or bent)

·         Condition of the wood (Colour, fungal diseases, rotten wood)

The time taken between the tree being cut and converted into wood pulp should be no longer than 6 to 12 weeks to obtain optimum pulp characteristics. Also, logs should be moistened when in storage during dry weather.

Storage condition can affect the processability of the logs for example too dry logs can lead to fibers being ripped from the wood resulting in more shorter fibers and fines 

Storage conditions

·         Carefully piled up on a well-prepared log yard

·         Ensuring sufficient water drainage - prevents wood rotting

·         Ensure air circulation

To learn about the next stage of wood processing click here;
Stone Ground Wood - Mechanical Pulp Production
Pulp Grinders - Mechanical Pulp Production

Consistency Measurement - Technical Papermaking

Consistency Measurement


Testing the consistency of a stock is the same as consistency of water solution. Consistency is the term given to the amount of solid matter within a body of liquid. The higher the consistency the more solid matter is present within the same volume of liquid. Consistency is measured in percentage; it’s a percentage/ ratio of solid matter to water in a certain volume.


To find the consistency we need to test the amount of dry content within a set volume of water. For example if we wanted the consistency of 100ml of water, and tested 25 gram of dry solids the consistency would be about 25%.

To capture the solid content within a solution a filter paper is used. Firstly the filter paper is weighed at 0% moisture (previously oven dried) and recorded. The stock sample is weighed (1g = 1ml) and recorded. The weighed stock sample is filtered through a vacuum and rinsed making sure all of the solids from the sample are on the sheet. The filtered solids and the filter paper go into the oven to remove all of the remaining moisture.

Once the sample leaves the oven it is weighed and recorded. This formula is used to calculate the consistency below.

Consistency=  (Mass of Solids)/(Volume of Liquid)

We have to calculate the mass of the solids captured on the filter paper, this is calculated below;

Mass of Solids=Total dry weight-Filter paper weight

Here are a list of results that I took from measuring the consistencies of a pulp preparation plant's stock flows through two fractionators and Long fiber screens.