CEN/TC/139/N 35?

CEN / TC 139/ WG2 / N355

Minutes of the 29th Meeting of CEN/TC/139/WG2 held in Bordeaux (CTBA) on Monday 15th and Tuesday 16th March 2004

Present:

Mr G GrüllAustria

Mr J Bach-ChristensenDenmark

Mr P SvaneDenmark

Dr P AholaFinland

Mme Christiane DevalFrance

Mme Laurence PodgorskyFrance

Mr A GötzGermany

Mr G Hora (Convenor & Chair)Germany

Mr B ReinmüllerGermany

Dr F BulianItaly

Mr Claudio MaganoliItaly

Mrs Bosschaart-ThurichNetherlands

Mr N J CoenjaartsNetherlands

Mr Frank NordskottNorway

Dr M PavlicSlovenia

Mr Anders GustafssonSweden

Dr E R MillerUK

Guests:

Dr Roland BaumstarkGermany

Mr G PauschGermany

Mr A RiedlGermany

Ms Kirsten WittenbergGermany

Mr D SykesUK

Apologies:

Mr E HäringGermany

Dr J Ekstedt Sweden

Mr Martin ArnoldSwitzerland

Mr Jon GraystoneUK

1Opening of Meeting

Dr Hora opened the meeting and Mme Podgorsky welcomed delegates to the CTBA.

2Apologies for absence

Apologies are noted on the previous page

3Membership of WG2

This item has not been discussed ??

4Adoption of Agenda (N339)

The Agenda was adopted without amendment and documents circulated since the last meeting noted. The Convenor explained that N 341 constituted the latest version of the draft of EN 927 Part 7. Document N 353 from Mr Ernst Haering was added to the list.

5Approval of previous Minutes

Minutes of the previous meeting in London (N327) were adopted. Mr Svane queried the statement in clause 8 of the minutes relating to film thickness of the ICP: ‘RRIV would be expected to show similar trends.’ He pointed out that film thickness was not an experimental parameter in RRIV.

Mr Gustafsson pointed out that when hard copies of documents were circulated at meetings of WG2 they would only be seen by those attending. Mr Götz agreed and pointed out that the presentation on sealer performance by Mr Arnold at the Braunschweig meeting had not been circulated. It was agreed that copies of documents and presentations made available at the meetings should be sent out subsequently to members not in attendance.

Mr Pavlic asked whether documents could be posted on a web-site, and Mr Reinmüller volunteered that DIN could offer to put them on Livelink. It was agreed that this would be useful and should be implemented.

ACTION: Mr Reinmüller and Convenor

6Latest findings on EN 927-5

Mr Götz outlined the repeatability study described in N 340 and presented the Recommendations. One concern was accuracy. Mr Svane suggested that a clause on accuracy be included as was quite normal in standardisation. Mr Reinmüller said a standard method was available.

There was discussion over the significance of moisture permeability limits. Dr Baumstark held that they were not of paramount importance because resin manufacturer’s could compensate with increased extensibility. Dr Miller pointed out that moisture permeability influenced decay risk as well as wood movement. Dr Bulian said that the water absorption test was very important to CATAS. He described a practical problem of excessive movement of wood shutters which had been successively explained by results from EN 927-5 testing. It had been shown that the problem stemmed from the replacement of a solvent-borne coating with a Water Absorption Value of 67.8 g/m2 by a water-borne product (WAV 128 g/m2). Dr Bulian acknowledged that the test had some shortcomings, e.g. sealing, reproducibility, but the test itself was nevertheless important for the market. There was a need to give thought to the limits, but not to question the need for the test. CATAS also had favourable experience of EN 927-5 in certification for over three years.

Dr Bulian and Mr Götz pointed out that in the application described a value of 128 g/m2 had given rise to problems, which suggested that it was too high for wood shutters.

Mrs Bosschaart-Thurich said that there was a need to address two issues, (i) where the limits should be set and (ii) the test method. She thought it was important to improve the instructions in the testing procedure. Mr Gustafsson referred to Jan Ekstedt’s extensive researches which had shown that repeatability was very good. Mr Svane thought it was necessary to distinguish between the precision of the test method, and the actual value.

Mme Deval said that CTBA used the test usually to compare a known coating to a new one. They had devised their own classification system on the basis of water protection efficiency (WPE) and found this useful and relevant. One complicating factor was that the value for uncoated wood differs for different species.

The Convenor went round table seeking member’s views. Mr Grüll said that Holzforschung Austria had a good experience of working with EN 927-5. Limits should be set on the permeability of the sealant. He did not agree with the focus on wood windows, other end-use applications were also important. He could live with the present limits for windows, but was unsure of the appropriate values for other applications. He questioned the relevance of having the semi-stable category; in his view only stable and non-stable were necessary.

Italy – Dr Bulian repeated his support for the method but said that the sealing material was indeed very important. The method should require a comparison between bare wood and panels coated completely with sealant.

Sweden – Mr Gustafsson expressed himself in favour of the method and also suggested that only two end-use categories were needed.

Finland – Dr Ahola said VTT had used the test for years without difficulty. It was necessary to use a good sealer and carry out the preconditioning properly.

Norway – Mr Nordskott said EN 927-5 was not much used. He thought there was a need for panels to be exposed to weathering before testing.

Netherlands: Considerable experience had been built up in SHR and the paint companies. Mme Bosschaart-Thurich and Mr Coenjaarts considered that two important issues needing to be resolved were the experimental procedure and choice of limits.

The Akzo Nobel results in document N 335 were considered. Some members considered that the results were very much in line with expectations, and there was general agreement that the high permeability of some coating systems was probably due to the presence of micropores arising from spray application. Mr Coenjaarts said that in a Round Robin conducted in the Netherlands the protocol had been closely defined to avoid problems. Dr Miller suggested that it was perhaps unreasonable to expect an institute to possess sufficient competence in spraying, and either the institute should apply the paints by brushing or the paint company should spray apply the coatings in house.

It was agreed that there was a need to revise Part 5. Mr Götz advocated the approach in the masonry coatings standard EN 1062-3 – no limits, just a test method. Mr Coenjaarts suggested keeping the limits suspended for the present, doing the necessary homework, improve the test, and then decide the limits. The following was agreed:

-the water permeability sub-group would be resuscitated

-the Convenor would collect comments and pass to the sub-group

-comments should be supplied in 2 months

-the sub-group to meet before the summer holiday

Membership of the sub-group would be the following:

Mr Coenjaarts, Mr Götz, Mr Svane, Mr Nordskott, Dr Hora, Mme Deval, BRE (to be confirmed) Mr Svane agreed to prepare a draft call for this meeting.

7.Round Robin IV

Mr Svane outlined the scope of the trial and reminded the meeting that its objective was to establish the repeatability and reproducibilityof the natural weathering test. Three coatings were included, the ICP and water-borne transparent and opaque systems. Mr Götz pointed out that after 2007 the solvent-borne ICP would not be allowed. Even if it could be used for research purposes, the raw materials might become unavailable. Katharina Bosschaart-Thurich undertook to look into the matter of availability of the raw materials.

ACTION: Mrs Bosschaart-Thurich

Dr Baumstark said that BASF would offer open formulations of water-borne products for adoption as an ICP replacement, and WKI offered to test them.

ACTION: Dr Baumstark and Dr Hora

It was agreed to delay the revision of EN 927-3 until the results of RR IV were available. Mme Podgorsky pointed out that most of the effort for RR IV was in the preparation of the samples. Re-exposure of the panels at the end of the 12 –month standard test could yield additional useful information for very little additional effort. It was agreed that extending the exposure to 2 years was a good idea.

8.Final vote on prEN 927-6 Artificial weathering (Item 11 of Agenda)

Mr Pausch introduced the final draft of prEN 927-6. He reported that he had received very few comments on the draft, though some had been given him at the meeting. He said that changes to the irradiation values in Table 1 would be required to bring them in line with ISO 11507. Mme Podgorsky said that the standard applied to machines equipped with the Solar Eye, and that standard machines could differ. Following a recent recalibration of the radiometer it had been found to have a new set point. Mr Pausch said that it was intended not to set a fixed value but a range. The normal QUV had an irradiance value of 0.68 when measured with a narrow angle. Experience in the USA indicated that a wide angle meter was more precise. Mr Götz expressed surprise that one kind of equipment needed to be set at 0.77, and another at 0.89.

Mr Riedl said that amendment was necessary to the informative annex on measurement. It was agreed that Mr Riedl and Mr Pausch would co-operate to in this. Mr Pausch said he expected all issues to be resolved in 2 months.

ACTION: Mr. Pausch, Mr. Reinmüller

9.Report on Internal Round Robin on EN 927-3 conducted by Akzo Nobel

Mr Götz reminded the meeting of previous water absorption investigations carried out for Akzo Nobel ( N 332 and N 335) which had shown that some products had water absorption values well in excess of the 175 g/m2 set in ENV 927-2. These included well-established commercial products that were known to perform well. In order to provide practical confirmation Akzo had accordingly organised an in-house Round Robin exposure test on 15 coating systems that were well-proven for stable end-use, among which were some that would not comply with the water absorption requirement in ENV 927-2. Exposure was carried out in Cologne and at Dormelletto, Italy. Mr Götz passed round for inspection several test panels which were considered to support the Akzo Nobel dissatisfaction with the water absorption requirement, in that the coatings had very high water absorption values but the condition of the exposed test panels was excellent.

A number of members drew attention to the very high quality and slow growth rate of the wood used for the test panels. It emerged that the wood used for the test panels failed to comply with the selection criteria in the following respects:

  • Growth rate up to 12 rings per 10 mm (requirement 3 – 8 rings per 10 mm)
  • Growth ring inclination 90 o - test face entirely radial (EN 927-3 requirement for ring inclination 5 o to 45 o)
  • Edges to panels rounded

Additionally some members expressed the view that the wood was more likely to be spruce than the Pinus sylvestris required in the standard. Mme Deval attempted to get the CTBA wood anatomist to check the wood species but this was not possible. However the wood has since been examined by the wood anatomist at BRE who states that the wood is indeed spruce.

It was acknowledged that the performance of the paints in the Akzo Nobel trial was very good, but that this could have been significantly influenced by the use of very high quality, slow-grown spruce instead of the pine as specified. It was considered that the usefulness of what was obviously a very comprehensive programme of work was reduced because of departures from the standard test procedure. The results could not be taken to support the Akzo Nobel argument. Mr Götz pointed out that he had been the customer for the work and had expected that it would be carried out in accordance with the standard; the problems that had arisen pointed up the difficulties in procuring wood of the required quality.

10.Amendment of ENV 927-2

Mr Reinmüller informed the meeting that the ENV had already been extended for 2 years and that it could now only be extended for a further 1 year. A decision needed to be made on its future. There was general agreement that the stumbling block was the inclusion of water absorption limits for stable and non-stable end-use categories. There was a lengthy discussion on the options for handling the water absorption requirements, and finally a vote was taken on the following 4 options:

1.Confirm the standard in its present form

2.Take out the water absorption requirement.

3.Leave the test as a mandatory requirement but omit the limits

4.Leave the table in its present form but insert an asterisk after the water absorption values in the table linked to a note stating that they were subject to revision.

There was overwhelming support for Option 4 and agreed that with this amendment the ENV could be circulated for Final Vote.

(It has since been suggested that an appropriate form of words for the note is as follows: *Non-mandatory values which will be revised/ratified in the light of ongoing work in CEN/TC 139/WG2.)

11.Resistance to knot and tannin stain development (prEN 927-7)

Mr Svane presented results in document N 348 on the use of an internal standard and explained that the work had failed to show any advantage in this approach. However he thought it essential to carry out a round robin evaluation of the test method. Mr Bach-Christensen offered to formulate a test protocol and get a group together to conduct the trial. Those expressing interest were Mr Svane, Mme Podgorsky, Mr Grüll, BRE (probably), and 4 industrial representatives, Mr Bach-Christensen, Mr Nordskott, Mrs Ahola, and Mr Gustafsson.

12 Measuring wet adhesion with a pull-off test – proposed EN 927-8

The need for a method of measuring wet adhesion was outlined by Dr Hora. Mr Svane broadened the issue by indicating the shortcomings in the adhesion test in Part 3, which carried through to Part 2. Why not return to a cross-cut, he asked. Dr Hora said he could not support the cross-cut, but would favour returning to the original method. The cross-cut had been introduced in 2000/2001 on a less scientific basis with hardly any practical experience. In Germany some Round Robins have been conducted which indicated that the cross-cut test is not appropriate and too subjective.

Dr Hora asked whether the group was interested in a new test for adhesion.

Mr Gustaffson said that painting of wet substrates was a problem, but there existed ISO standards for adhesion. Mrs Bosschaart-Thurich considered WG2 had enough on its plate, but the problem with the cross-cut was the depth of penetration into the substrate. Mr Grüll would not support a step back to the cross-cut, but would support a step forward. Norway and Sweden were not in favour. Slovenia used the pull-off for testing adhesion before and after weathering, and would support the work. Mr Coenjaarts considered that the best solution was to define the cross-cut test more tightly, but would go along with the work.

Mr Reinmüller said that if the test was not a mandatory test method there was no need to make it a formal EN test method. It could be covered by a European Technical Report. This was a very swift process; approval depended only on the opinion of this group of technical experts. An alternative option was to ask ISO to revise the ISO standard. Mr Maganoli said that adhesion was of interest; existing methods had deficiencies, therefore the work was justified.

In the light of the generally favourable response it was agreed to form a task group on adhesion. Those expressing interest were as follows:

Mme Podgorsky, Dr Hora, Mr Götz, Mr Maganoli, Dr Pavlic, Mr Grüll

Mr Svane reminded the meeting that urgent attention needed to be given to the need to resolve the adhesion test in EN 927 Parts 2 and 3.

13.Future role and activities of WG2

The Convenor introduced document N 342 and reminded members of the changed climate in regard to support for research. There was much discussion on whether public bodies actually had any need for EN 927. Dr Miller said that use of the standard was hindered because the performance standard existed only as a pre-standard, or Draft for Development. Mr Bach-Christensen said that public bodies were required to use EN standards, but not ENV’s. Mr Gustafsson said that only Part 1 was used; Norway and Finland expressed themselves as ‘unenthusiastic’. Mr

Grüll said that in Austria EN 927 had had a very great influence on the joinery sector. Conversion of ENV 927-2 into an EN was a most important step and would encourage harmonisation and more reliable test methods. It was reported that in France national standards were of most relevance; EN 927 was not mentioned because Parts 2, 3 and 5 were all needed. However, a new French standard for joinery finishing systems was in preparation and EN 927 would be incorporated.