We repeated our Fundamentals of Light Fastness testing webinar, so have move informative and interesting Questions & Answers to share with you. The key topics covered in part 2 were:
A: No, the test cannot be sped up, although the test is long it is a sped up version of ageing fabrics in real sunlight. The only way to shorted the duration of testing is if the customer wants a shorter test to a lower blue wool grade – i.e. to a BW2 rather than a BW4, but you wouldn’t be testing to the full extent of the standard.
A: We recommend continuous checking, we’ve discussed that light fastness testing takes a long time, you don’t want to get to the end of your test duration to find out your radiation was incorrect. The TruFade SolarSens measures the irradiance constantly.
A: For James Heal’s Xenon Arc tester, we would not advise testing products like PET film and plastic. The instrument has been designed to test textiles. We cannot advise on other manufacturers instruments.
A: Sample holders can accomodate samples up to a thickness of 3mm. As carpets are generally thicker than this, the James Heal TruFade cannot test carpets.
A: No, the fading times are different. The approximate timing examples given in the presentation relate to ISO 105 B02 A1 (Temperate climate) only.
A: This is a difficult question as the results are not related to the samples real life performance, but rather indirectly as an indication. It is then up to specifiers, such as retailers, to specify a blue wool rating to a level where the fading is acceptable, commonly where they will not get complaints.
You need to know the specific test that your rating relates to that has been carried out on your fabric before attempting to establish the approximate fade time under given conditions. For example, On an ISO B02 A1 Temperate setting of (47 ± 3) °C, 40 % effective humidity & (42 ± 2) W/m2 irradiance it takes approximately 80 hours of continuous exposure for a blue wool 5 to fade to a grey scale 4.
A: The Grey Scale is used to grade the blue wool, then the blue wool is used to grade the specimen. Our light fastness webinar details a lot of this process, you can watch or rewatch it here.
A: For ISO light fastness standards, you can include 10 x 10mm deep specimens. You can also use a combination of larger samples or just one sample. You can see a couple of layouts on the image below.
A: The best place to begin is by contacting the local textile college and visiting libraries (local & online). Search online to see if there are any textile associations to join these can be a good source of information and some offer courses, they are also a good place to network. Linked-In is also another good source for contacts. We have educational resources on our blog, and you can also watch our range of webinars on demand for further education.
A: Yes, they perform to AATCC 16.3 & ISO B02, please see brochures & the relevant standards. In the TruFade, all the standard parameters are pre-set into the machine and the required time is set by the operator and the test is begun using the start button. If you have a TruFade please see the Operator’s Guide and/or contact us to arrange training.
A: You are referring to methods in the standard ISO 105 B02. See Annex E.6.2 for Method 1 & E.6.4 for Method 3 in the ISO 105 B02 2014.
A: Every retailer has different requirements, but we would recommend referring to Marks & Spencer as they are a great example for these garments.
A: It is possible for this to have an impact, try reading Annex E.4.6 & E.8.3 in ISO 105 B02 (2014) for more information.
A: For blue wools, if properly stored, they can be used for at least two years. Proper storage means unopened in the original packaging in a dry, dark place, protected from direct sunlight and as cool as possible. The environment should be free of chemicals and air pollutants. For the lamps, we refer you to Q&A part one, guidance on when to change lamps can be found here.
A: Grade 3 water is specified because it has low concentrations of mineral deposits, tap water would contain these which would then deposit inside the instrument and onto the specimens. The water needs to be as pure as possible to keep the machine as clean as possible. Also, the quality of tap water varies from country to country – we talk a lot about controlling variables for accurate and repeatable testing, the water you use is one way of doing this.
A: It is difficult to disagree with the points raised in the question and there will be many views from experts around the globe, but we feel it is too complex for us to answer this far reaching questions. However, we will put the question to our National Standards Body who will then (hopefully) put the question to the expert panel. Nevertheless, I think they will feel that they cannot progress unilaterally and may seek the involvement of bodies such as ISO and scientific/environmental research organisations to undertake a review of the data and its potential influence on light fastness and weathering testing standards.
Obviously the outcome of such studies could have far reaching effects on standards related to textiles and many other industries too. As you can imagine, studies of this nature take years, may be even decades (and may indeed already be in progress or completed), to reach conclusions and formulate predictions which can be used to update future standards.
A: There are two others that we are aware of, Mercury Vapour & Carbon-arc. The TruFade uses Xenon Arc only.
A: The instrument should stay within the set climate settings: Temperate (A1), Dry (A2), Semi-Tropical (A3).
A: This is what ISO 105 B02 Clause 9.1 states, so any change from this must be agreed between interested parties. The regeneration time is a minimum of 24 hours.
A: You can use any material as long as it is opaque and able to withstand the chamber conditions, however you might need to run some testing to ensure this is the case. We would always recommend purchasing the proper sample masks to ensure your test completes correctly.
A: No, the ISO and AATCC blue wools are not comparable. To maintain continuity between tests and to be able to confidently compare results, we recommend only using one kind. Below, you can see ISO Blue Wools on the left, and AATCC Blue Wools on the right.
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