Services

They encompass the entire textile pipeline from farm to consumer including test houses. Through technical committees established over many decades, the IWTO issue test methods for a plethora of physical properties of wool. In holding an IWTO testing licence, we are authorised to use these test methods to issue IWTO certified test results to our customers and they form the basis of standardised testing around the world.

Before an IWTO certificate can be issued, there are sampling, testing and documentation requirements that must first be met, all stipulated in the IWTO test methods and regulations. Our highly skilled team of testing officers, technical personnel and samplers are all trained in these IWTO requirements. WTAE are in control from the moment a sample is taken to when the test certificate is issued. By being in control of the entire process, we ensure that the IWTO testing requirements are being employed at every stage of the process and because of this, our test results are guaranteed.

Our obligation does not stop at the point of issuing a test certificate. We also have robust customer complaints policies in place, including an office located in Shanghai, to ensure that any problems are swiftly dealt with and investigated.

Where IWTO certification is not possible or not required, customers can submit their own samples for testing. WTAE will issue a test report rather than a test certificate. This is usually the case where IWTO sampling has not been possible.

All samples submitted for report testing are still tested according to the IWTO regulations however the sampling integrity cannot be guaranteed. We may also “downgrade” a test certificate if we are unable to satisfy our stringent quality control criteria. Customers are notified in advance if this has happened during the testing of their sample.

Many of our customers use our report testing service if they are carrying out their own internal quality control of their lots. Although the results are not IWTO certified, the test reports provide enough information for merchants and processors to know what they have in their warehouses and how to compile blends based on their own customers’ needs in the future. Some customers will then go on to select specific lots for IWTO certification which allows them to complete the sales transaction.

For IWTO certified testing, samples can only be taken by our specially trained sampling agents. This is important for 2 reasons:

The samples have been taken impartially. WTAE has no commercial interest in the test result therefore it is imperative that we take the samples. This is a key requirement in the IWTO sampling regulations and probably the most important.

The samples taken will accurately represent the lot that the samples were taken from. This is done by ensuring all bale weights are accurately obtained and recorded. Other information is collected and verified during the sampling process such as lot identifiers, location and date of sampling, the agent who took the sample and any other information deemed necessary.

Buyers of wool want to know how much wool they are actually purchasing. This makes sense as raw wool is full of many impurities and once these impurities are removed, the physical weight of clean wool fibre can be much less than the original weight of the greasy wool lot. The yield test does just this – takes the greasy wool sample, removes all the impurities, and informs the buyer of how much clean wool fibre they have. This is applicable to all natural commodity industries.

Wool Base

Wool Base expresses the amount of clean, dry wool fibre once all the impurities have been removed. It is expressed as a percentage. Three impurities are removed and determined by the laboratory; ash content, grease content after scouring and vegetable matter content.

Vegetable Matter

Vegetable matter content, or VM is the percentage of a sample which is made up of burrs, hard heads, twigs, seeds, leaves and grasses. Vegetable matter is picked up by the animal as it moves around it’s environment and is classed as an impurity. Therefore, it has to be separated and quantified. The vegetable matter content is displayed on our IWTO certificates expressed as a percentage.

The Wool Base and Vegetable Matter Base results are used to calculate the amount of clean wool fibre that is expected to be produced when a lot of raw wool is processed i.e. the “yield” of a lot.

This is not the case when lots are commercially scoured and processed and there will inevitably be some fibre loss during the commercial process. Once we have determined the wool base and vegetable matter content of your lot, we can then calculate commercial yields. There are far too many commercial yields to list here but the most common are:

IWTO Scoured Yield at 16% regain

Derived from wool base and vegetable matter, adjusted for an ash and grease content of 2.27% and moisture regain of 16%. This does not take into account processing losses during scouring.

Schlumberger dry

This is a processing yield and estimates the maximum yield theoretically possible if all wool fibre in a lot is converted into top & noil, less an appropriate allowance that accounts for fibre loss during removal of the vegetable matter.

This can have a substantial effect on the measurement of wool samples particularly micron. Therefore, all testing must take place within a controlled environment. The IWTO testing regulations state that the optimum conditions for micron measurement is 20°C and 65% relative humidity. Our conditioning laboratory is controlled at these conditions 24 hours a day, 7 days a week and is continuously checked by our monitoring systems. All IWTO licenced fibre testing laboratories will have a conditioning laboratory like this, and it ensures harmonisation across all test houses.

Test samples are dried to 0% regain (zero moisture content) and are then placed in the conditioning laboratory for approximately 18 hours before being read for micron and colour. Samples that have been in the conditioning laboratory for the desired amount of time are said it be “conditioned”. This means they have reached an equilibrium with the atmosphere of the conditioning laboratory.

Like fibre diameter, colour is an important wool attribute and the measurement assists the dyer when the wool is being processed. If a very light pastel colour is required the wool must be very white and bright. On the other hand, if dark colours are to be dyed, stained and dingy wool could successfully be used.

N.B. Colour results are only valid for 6 months after testing; any IWTO Test Certificate or Test Report issued with a colour result older than 6 months will include the wording “Colour readings expired”.

The surface area of the wool fibres creates a resistance to the flow of air. The finer the wool, the greater the surface area and the greater the resistance to the flow of air. The volume of flow reduction can be accurately measured on an Airflow meter to equate to mean fibre diameter.

Internationally accepted calibration wools of known fibre diameter are used to calibrate the Airflow meter to produce very accurate and consistent results. The measurement theory of the airflow method assumes that fibres have a constant density. Therefore, a fixed weight of wool of the same average diameter will always give the same amount of fibre surface and average micron result.

An exception to this rule is created by the presence of medullated fibres that have a hollow inner core. In these fibres, the overall density is often lower than that of non-medullated fibres and a slightly finer result is possible than if the fibres were measured using the LASERSCAN instrument. Similarly, lambs wool may differ in density to adult wool which can have, to a lesser extent, a similar result.

To obtain a measurement, 2 separate samples are precisely measured from the same global conditioned sample. Each sample is read across two airflow meters twice, generating in total 4 readings. These are averaged and the final result reported to you. Internal quality control is performed between the 4 individual readings, excessive differences prompt our testers to perform the test again so to satisfy the IWTO requirements.

Snippets are taken from a scoured and conditioned sample using a minicoring machine. The snippets are then read using laserscan. Many 1000’s of snippets are read to generate the following information:

• Mean fibre diameter
• Standard deviation
• Coefficient of variation
• Comfort Factor (the number of fibres measuring less than 30µm)
• Fibre curvature
• A histogram showing the spread of fibre diameter in the sample

The same parameters are determined as with laserscan:

• Mean fibre diameter
• Standard deviation
• Coefficient of variation
• Comfort Factor (the number of fibres measuring less than 30µm)
• Fibre curvature
• A histogram showing the spread of fibre diameter in the sample

The Conditioning test measures the amount of moisture in a scoured wool sample. The test is used to calculate the Moisture Content, Regain, and the true weight of a lot at a specified moisture regain; this is called the Invoice Mass.

This is not to be confused with “conditioned samples” as explained in our conditioning laboratory section.

• Residual Grease (IWTO 10)
• Combination certificates (IWTO 31)
• Core Bulk & Resistance to Compression
• Staple & Fibre Length
• pH