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Innovative solutions for improved processing of Beech (Fagus sylvatica L.) with red heartwood (Innovation for beech)

Final Report Summary - INNOVATION FOR BEECH (Innovative solutions for improved processing of Beech (Fagus sylvatica L.) with red heartwood)

The overall scientific and technical objectives of the INNOVATION FOR BEECH project were to optimise the processing of beech round wood containing red heartwood and to develop high-value products of red heartwood.

Within the frame of the overall objectives, the project has the following specific objectives:
- to complete the actual international state-of-the-art, relevant to the subjects of the project, concerning knowledge and experience which is not per-se publicly available or with respect to the latest developments;
- to optimise the timber grading by a prototype optoelectronic system for automated discrimination and determination of light wood and red heartwood, but of other visual grading criteria (e.g. branches) as well;
- to increase the yield of light beech wood by optimising the sawing of timber containing red heartwood based on the results of the optoelectronic grading system;
- to homogenise the variation of red heartwood appearance (colour and structure) by developing adapted steaming regimes for roundwood and sawn timber, to stabilise the appearance during technical drying and to optimise the colour homogenisation by UV-treatment;
- to develop high value red heartwood products focussing on glue-lam beams, thermo wood and furniture. The quality of laminating and the mechanical properties of the beams shall be analysed. Raw material with a homogenised appearance (colour and structure) shall be used for developing solid wood furniture products as well. Regarding the thermo wood, its suitability for outdoor use in terms of colour change through ultraviolet exposure, shrinkage and swelling as well as glueability shall be analysed.
- The market potential for the newly developed semi- and end-products shall be evaluated (The corresponding goals are stated above together with those of each specific semi- and end-product).
- to develop integrated concepts for managing red heartwood at all relevant stages of processing.

The project was structured into 4 work packages (WPs), with respective sub-WPs, as follows:
WP 1: Survey of existing technology and products;
WP 2: Maximum yield of light wood;
WP 3: Homogenising red heartwood colour;
WP 3.1: Homogenising the colour of red heartwood by steaming;
WP 3.2: Stabilising the colour and improving the properties of red heartwood by drying;
WP 3.3: Stabilising the colour and improving the properties of red heartwood by UV treatment;
WP 4: High value products of red heartwood;
WP 4.1: Red heartwood glue-lam beams for constructions;
WP 4.2: Red heart 'thermo wood' for outdoor applications;
WP 4.3: Red heartwood for visual application in furniture.

All questionnaires of the inquiry have been analysed and the results were available as a part of a report of the results of the survey in WP 1. The results were presented at the second European hardwood conference on 6 September 2005 in Sopron, Hungary, by BOKU. Additionally the report has been sent out to all, which answered the questionnaire in each participating country. Literature review was carried out by every research institute in his home country. The review included both public (journal articles, etc.) and 'grey' literature (research reports, PhD theses, etc. mainly from research institutes). In order to coordinate the literature review, a current list of references was provided on the project web page, which should be updated continuously.

The objective of WP 2 was to develop the software module for automated detection of red heartwood. With the help of the proved red heartwood determination system it should be possible to increase the yield of light beech wood by optimising the sawing of timber containing red heartwood. The development of the special software module was and is far more sophisticated as expected. So it took much longer to reach the determined objectives getting an appropriate and approved running system.

Tests on real timber faces under practical conditions as well as the fine-tuning of the software algorithm were carried out. The results showed that the combination of hardware components and software with newly developed algorithms made this system able to recognise the defects on wood as well as detect red heartwood. At the end, a system is developed, which is running but has to be optimised. This will be done with other industrial partners, which are interested in the system, or in the software algorithms respectively. First contacts were established during the final workshop at international trade fair LIGNA+ in May 2007 in Hannover.

The objectives of the WP3.1 'steaming' were to analyse the influence of different schemes of steaming for the colour of red heartwood in round wood and sawn timber, com-pared to the surrounding light heartwood. Industrial schedules of steaming to establish de-sired levels of colour were developed. For homogenising of the colour steaming schedules were created. Diverse steaming schedules were mapped and steaming was carried out at different temperatures and moisture contents. Qualitative analysis of the acidic components in the waste water and quantitative analysis of the acetic acid have been carried out. During the last period colour measurements were carried out after conditioning and industrial schedules of steaming to establish desired levels of colour have been developed. The results are available and several aspects are already published.

In the WP3.2 'drying', convection drying experiments according to the project plan have been finished. For high temperature drying, a climate chamber of BOKU was adapted to carry out high temperature drying with hot steam. Test drying experiments have been done in order to optimise the drying schemes according to drying quality and wood colour. The adaptation of the high frequency vacuum drying chamber of BOKU for conventional vacuum drying has been finished. The most promising schedules were optimised in the second step of the WP together by BOKU and MIKO. The data obtained of the different drying methods were analysed in terms of a desired colour and drying quality in general. The optimised drying schedules are available and partner MIKO will adapt most the most promising schedules.

For homogenising the colour of the red heartwood and the adjacent light wood by UV-treatment, samples were treated with different drying processes and UV expositions with changing conditions: speed of the UV train, kind of lamps (galium [400 - 425 nanometres] and mercury [300-450 nm] lamps), UV intensity, and number of cycles in the UV train. Experiment led to conclusions on the best changes in reducing colour differences by different technical parameters. Some samples were tested at AIDIMA in order to determine colour durability after UV-treatment. The test consists in placing the samples behind a window in order to check colour behaviour for indoor use. The results are available and in parts already published.

The development of high value red heartwood products focussing on glue-lam beams, thermo wood and furniture was the aim for WP 4. In WP 4.1 'gluelam beams, the quality of lamellas has been analysed with regard to red heartwood content and wood features. Tests on glueability of red heartwood have been done. Strength tests of finger joints in regarding the influence of red heartwood were done. Gluelam beams made out of Beech timber were produced and shear strength tests were carried out at the material testing institute MPA Stuttgart.

The objectives in WP 3.2 'thermowood' were to treat dried red heart timber with high temperature to improve natural durability and dimensional stability and to evaluate the suit-ability of 'thermo-wood' to outdoor use in terms of colour change through ultraviolet expo-sure, durability, physical and mechanical properties, shrinkage and swelling as well as glue ability. Tests have been done according to the amended work plan, caused by the fire at MIKO. The results were reached and most of them published already. As for the use and the market potential of thermally modified timber some studies are available, these studies have been analysed and evaluated according to thermo wood containing red heartwood. As colour change is relatively fine related to defined treatment schemes and properties of TMT (thermal modified timber) MIKO is developing an online system for colour measurement to optimise the treatments and to assure a defined quality in terms of colour and product properties.

Furniture designs studies using red heartwood timber have been performed. Several designs have been chosen for further development and the production of prototypes. The prototypes were presented to key representatives of furniture sector.

By analysing the results, the following conclusions can be formulated:
1. red heartwood market share could reach up to 5 %-10 % of beech manufactured furniture.
2. companies and end users have little knowledge about beech red heartwood. Importers, as normally suppliers of the furniture companies, act normally as prescriptors of the material, so that in the import red heartwood has been normally rejected.
3. colour heterogeneity is a main barrier to market entry of red heartwood furniture:
a) companies think that supplying material with a good colour classification is difficult;
b) they think many consumers do not accept red heartwood. Beech furniture is associated in the consumers’ perceptions to light colour with homogeneous figures.
4. in order to be accepted by industry, red heartwood products should be cheaper (about 10-20% cheaper) than other similar products; price is the key to reach a significant market share for heartwood furniture.
5. the modern design of the virtual prototypes has been well considered by companies, so modern design could help to sell red heartwood furniture. The penetration in the market should be connected with a clear trend of the furniture. In the future, red heartwood should be directly associated to design furniture in modern style.
6. the value and visibility of red heartwood furniture could be increased through trade shows/events and industry publications. Nevertheless, the material should not be the main marketing argument, much more the design.