The International Association of Wool Textile Laboratories – INTERWOOLLABS – was set up in June 1969 in Paris at the 38th International Wool Conference.


The International Association of Wool Textile Laboratories aims are:

  • To develop co-operation between the Member laboratories, with a view to ensuring the most correct and uniform application of approved testing and sampling methods as set out in the Specifications of the International Wool Textile Organisation and in any associated International Wool Textile Organisation Regulations;
  • To ensure that Member laboratories obtain accurate test results which have a high level of precision, in their application of those specific International Wool Textile Organisation test methods and procedures which are relevant to INTERWOOLLABS' approved annual work programmes;
  • To assist Member laboratories in resolving disputes arising from differences in test results, by ascertaining the causes of any discrepancies.

The Association is open to Institutes and Firms with test laboratories, whether or not they are located in countries whose wool-textile industry is affiliated to the International Wool Textile Organisation, and subject to their equipment being in conformity with a minimum of clearly defined technical criteria.


INTERWOOLLABS was an immediate success. 66 laboratories applied for and were granted membership of the Association in 1969. INTERWOOLLABS now has 84 Members in 25 different countries.

At the request of the I.W.T.O. first and then of Members, INTERWOOLLABS has set up laboratory harmonisation schemes in the following areas :

  • Fineness measurement of wool tops using the AIR-FLOW apparatus (1969);
  • Fineness measurement of wool tops using the PROJECTION MICROSCOPE (1970);
  • Fibre length measurement of wool tops using the ALMETER (1972);
  • Fineness measurement of wool tops using the LASERSCAN (1997);
  • Fineness measurement of wool tops using the O.F.D.A. (1997).

Our activities have led to an ever greater harmonisation of members' results in respect of length measurement using the Almeter and of fineness measurement - using the Air-Flow and Projection Microscope first, and later the Laserscan and the O.F.D.A.

The calibration standards which we have regularly brought into being have continually improved in quality, as our criteria for selection and control have become ever more stringent.

In view of the development of technical standards and measurement machinery, we have also strengthened the internal discipline within the organisation : our Statutes have undergone a number of 'facelifts', our procedures and regulations have been brought up to date.

Harmonisation Contribution

Our contribution to the work of I.W.T.O., and in particular to that of its Technical Working Groups, has been and remains important. Our work has served as a reference and a starting point for many reports and studies.

Finally, we would like to draw attention to the fact that this very positive state of affairs is to a large extent due to our Presidents – our founder President Walther DELIUS first of all, then Ralph HULLAH, Richard BOWNASS, Umberto FRACASSI, Yves GRAUX and William AINSWORTH. Nor should we forget to mention the members of the Management Committee who devote so much of their precious time to these activities which are essential to the further progress of INTERWOOLLABS.

Harmonisation of wool textile laboratories has been gradually achieved thanks to the establishment of regular strict controls to which Members must submit; these controls have been made possible by a system of round-tests carried out every six months.

During these round-tests, laboratories are asked to measure the fineness (or the length) of a certain number of samples which are sent to them and which have been obtained from the same lot, previously homogenised. The results are then studied in complete anonymity, through a code-number guaranteeing total confidentiality of individual results. If their results are found to be within the Association's limits of acceptance, in relation to the overall average obtained by all participants, laboratories are considered and recognised to be 'calibrated' and calibrated and receive INTERWOOLLABS' calibration stamp, valid for one year for the measurements in which round-test results have been found satisfactory. On the other hand, in the event of excessive deviations in their measurements, laboratories are obliged to undertake a re-test, and if difficulties encountered persist, the Association offers its help in order to resolve the problems.

The results obtained in inter-laboratory harmonisation may be considered to be most satisfactory.

Each year Interwoollabs submits a report to the Raw Material Group of the IWTO summarising the results of the inter-laboratory harmonisation Round Tests.


The INTERWOOLLABS stamp on test certificates guarantees that the laboratories issuing them have been calibrated by INTERWOOLLABS.

This stamp shows the year for which it is valid, the identification number of the laboratory, type(s) of measurement for which the laboratory is 'calibrated' and that the programme is for wool tops only.

  • All wool tops purchased for INTERWOOLLABS' use must be of good style, having normal levels of medullation (i.e. in the coarser qualities) and preferably being comprised entirely of fleece wool.
  • All wool tops are gilled a total of 6 times (including the normal combing gillings) to ensure homogeneity. Tops having an estimated fineness of less than 23 microns are double combed before the final gillings.
  • Whenever the results of round trials on newly purchased top show poor agreement between the average Air-Flow and Microprojection results, the top will not be used again, remaining stock will be sold and a replacement top will be purchased. The aim is to have as many suitable tops as possible from which to select the future series of standards.
  • To increase the available number of potential standard calibration tops (given that repeat round-tests must have been conducted to establish accurate nominal values and to obtain both Air-Flow and Microprojection values for each such top), the number of top lots per round-test has been increased since 1987. In the case of Air-Flow, Laserscan and O.F.D.A. tests, a total of 8 lots are tested. In the case of Microprojection, a total of 4 lots are tested.
  • Before any new series of IH. calibration standards is issued, the standards provisionally selected by the Management Committee will be subjected to a final calibration check among the Committee Members' laboratories to ensure that they produce an acceptable calibration curve, as defined in IWTO-6.
  • In determining the nominal value for each IH. standard to be used for the calibration of Air-Flow instruments, the average Air-Flow results obtained from the repeat round-tests will be used (excluding statistically selected outliers).
  • In determining the nominal value for each IH. standard to be used for the calibration of Laserscan and O.F.D.A., the average Projection Microscope results obtained from the repeat round-tests will be used.

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