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Recent QoR Lightfast Testing

8 thoughts on “Recent QoR Lightfast Testing”

  1. I find it fantastic that you make such a big database accessible to your customers. It is great to be able to compare so many swatches. Only one thing I personally would have changed. I would have preferred to see the tests on high quality paper. When looking at the diluted Ultramarin Pink or Ultramarin Violet, it is clear that the paper yellowed more than the Pigment. But with the colors with higher tinting strength, this is not clearly distinguishable anymore and is not clear how much is paper change and how much is Pigment change. And it might seem that the color has changed, while in reality it is the paper. Kind regards,

    Reply
    • Thanks for the feedback Mara. We intentionally used a student-grade quality paper to start this testing so as to have results that were more critical of the paints and less reliant on the paper for good results. You are correct that as you dilute the watercolor the paper will have more exposure. We are planning to test the paper independently to see what that looks like without the watercolor and in the future we hope to expand upon this testing by including additional papers to see how this might affect lightfastness. This is the first step and these points you bring up are great next steps for us to consider. Thanks for reaching out, we appreciate the feedback! Warm Regards.

      Scott

      Reply
  2. Thank you so much for posting this, very useful and informative!

    I saw the result for Titan Buff in your acrylics before, odd that it reacts with the Xenon acceleration as I don’t think iron oxides or titanium white on their own do?

    The PG7 result is very odd though, never heard of this issue in any other lightfastness testing and results..?

    Reply
    • Hello Richard, Thanks for the interest. We did not see this same darkening with Titanium White or with Iron Oxides in our testing. The Phthalo Green Blue Shade was an outlier as it showed this darkening only in the application that was minimally tinted with white. The Spectro read it as a shift towards red and a darkening in value, visually it is noticeable, but it is nice to see the visual next to the Delta E to compare. It tested well under the other test conditions, so it was an interesting result we will keep our eye on.

      Reply
  3. Thanks for sharing this information! The results about Titan Buff are a little disturbing… is this darkening also likely to manifest in acrylics?

    Reply
    • Hello Asaf,

      We have seen some similar darkening in the media we have tested, including oils and acrylics. Lightfastness is strongly pigment dependent, while there can be some role the binder plays, pigments will often test similarly in terms of lightfastness in different binder systems.

      Scott

      Reply
      • Thanks Scott. I think it’s worth noting that somewhere in the paint descriptions, particularly because there are alternative mixtures which are likely safer.

        Reply
        • Hello Asaf, thank you for the suggestion, we will pass this up the chain. You could certainly make a mixture that resembles this color if there is concern. While we have tried this ourselves on many occasions with a variety of colors, matching a single pigment color is not an easy task. There is the color quality, but also the performance properties that are unique to a pigment. We will put this to the team again though and add it to our New Product Idea bank!

          Reply

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