White Mat has purple hue

Alan Yaffe

Alan Yaffe

CGF II, Certified Grumble Framer Level 2
Industry Vendor
Joined
Mar 8, 2006
Posts
334
Loc
Peterborough, Ontario
Business
Peterboro Matboards CEO
Is it possible for a white mat to have a purple hue when using acrylic?
 
@Alan Yaffe
did you figure it out? lol my curiosity is running wild since it was marked as resolved.
Did the type of acrylic cast a purple hue?
Was it the light?
Or was this particular white just more purpley than the other 3000 white mats out there?
Let me guess... you were wearing a purple shirt!
 
It was not resolved - that was me trying to edit my post for a typo. We have a customer that says the white they use turns to a purple hue in the frame. We couldn't see it at our end but I know they use acrylic and wondered if that was causing it?
 
I have seen acrylic which has a purple cast when viewed edge-on. It is usually very thin, so it may be some other type of plastic. We had customers tell us on several occasions that their white mat was turning some color or other when they hung the artwork in their home. It was always the lighting. The problem disappeared once they brought it back to our shop. Sometimes it was the color of the wall they hung it on that threw the color off.
 
UV and A/R films/coatings can cause color shift in either bounced or transmitted light. More with glass on the UV side, but pretty equal glass/acrylic on the A/R.
if this is a white mat board with optical brighteners, there may be a color shift from old fluorescent tubes and for some LEDs.

I removed the "resolved" sticker Alan.
 
It is a very bright white and does have OBA,s. Since they fluoresce purple under UV I suspected that the OBA,s were causing the problem. I was just curious that this had not come up before?
Thanks everyone for your response.
 
When we used to purchase a lot of dyed textiles in various overseas mills we purchased a lightbox to view the samples that were submitted to us for approval. This box allowed us to view the color samples under various different light sources to see how closely they matched the samples we submitted as a standard. We would have to let the mills know which light source we were using in the approval process so they would evaluate the samples under the same criteria. It always amazed me how the frequently the samples would change under the different lighting types. This is especially the case with blacks and whites. Blacks would "flare" to the brown, blue, red and grey depending on the source and whites, especially those with optical brighteners would change dramatically as the light sources were changed.
 
Rick not many people have your experience with the difficulty of dealing with color. We match paper using D65 at 10 degrees. That is 6500 degrees on the Kelvin scale, which they tell me is the temperature of the surface of the sun, and the closest thing to daylight and 10 degrees is the angle of the refected light when viewing or measuring the color on a spectrophotometer. With all this standardization and computer assistance, one would think that color matching would be much easier. It is clearly the most difficult issue to deal with in paper making. Once the paper has been turned loose we never know what light and angle it will be seen in.
It is clear that the Plexi being used in the case of our customer is causing the issue as they have bought thousands of this color for years without issue. I am guessing that they may have changed plexiglass suppliers recently. I am curious to know if they are now buying from China like so many OEM's.
Thank you everyone for you input.
 
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Interesting that 6500°K is the standard for measuring color, as very few real life environments are lit with that- it would be far too harsh. (I don't even like 5000°K in a home or restaurant setting.) In my shop, I try to have lighting which is representative of what people will be using in their homes or offices to view the finished framing, so there will be no unpleasant surprises.

I have long noticed that certain colors of anodized metal mouldings look very different in my design area (which has a combination of natural light and LED lighting at 3000°K) and my back room work area that has 3500°K fluorescent lighting.
:coffeedrinker2: Rick
 
Alan, it was also the most difficult issue to deal with in the textile industry. We would primarily view the dyelot samples under three light sources, incondescent, flourescent and daylight. That was the extent of technology at the time that mills in eastern Europe, China and India offered for color matching. Western European mills were a little more advanced. Of course the outcome depended on many factors including the state of the greige goods when the bleaching process began, the color of the yarns that the greige goods were constructed of and of course the quality of the actual dye ingredients and the expertise of those involved with the entire process. Then there was always the "Acceptable Range of Variation". Which was always one thing from our point of view and another from the mills. It sounds like your process is more detailed than that. I don't envy you.
 
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We use daylight bulbs in the shop.
Past that I have no idea what the degrees Kelvin is.
Interesting to see that the standard Alan uses is Cooler than Daylight (5000K).
 
I wonder what K temp those super-white GU-10 bulbs used in jewelry stores, Swarovski Crystal stores etc. are.

:coffeedrinker2: Rick
 
Lighting has changed over the years and the mills just want something standard to match with. When I started in the 70's we had track lighting in the gallery which was very in style. Later we replaced the incandescent with quartz and halogen. Mills at the time were matching for our industry using F10 flourescent which is what most of us had in our work spaces. Now a lot of people are using LED and the mills requested we shift to D65 about 10 years ago. We also view our colors in three different light sources to get an idea of color shift but it is D65 we match in. To add a further wrinkle, pigmented colors use at least 3 pigments to achieve a color. All or one can be metameric cause a great deal of idegestion!
Thank you for posting the lighting guide. It gives perspective.
 
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