05 Dec Difficulty in Color Matching
It is extremely difficult in screenprinting to create a specific color of ink on the press, and expect that it will exactly match the print from a previous job. It is impossible for anyone who does not have the entire process under absolute control.
Bill Hood, ASDPT Fellow
Allow me to briefly explain the difficulty that you are faced with when trying to match a color. But, there are a few who have control over their process and can perfectly match a color.
You will get a different hue, by changing any variable in the process.
There are a total of at least 620 known variables in the screenprinting process. And, each of them is possible of affecting a change in other variables. When you change just one variable, you may inadvertently be changing the outcome of many other variables, which then have to be altered to correct for the change you made. Let’s take just one variable that few screenprinters have under control that grossly affects the hue of a color.
When tension changes slightly, there is a change in the mesh opening volume. The threads are pulled further apart as tension increases or moved closer together as the tension is reduced. As the mesh opening volume is altered, so is the amount of ink transferred to the substrate. And, this affects the hue of the printed color. Tension change also affects dozens of other variables, such as the off-contact, fill blade, and squeegee settings, and of course, each of those adds to the color change, as well.
Maintain tension levels to assure ink volume!
You have no control over the substrates that you put on the press. Substrates change slightly between batches, which will affect the color created with some ink deposits, and especially on water-based inks.
Simultaneous Color Contrast
The perceived color at each point in a visual scene depends on the relationship between light signals from that point, and light signals from surrounding areas of the image. In the well-known phenomenon of simultaneous color contrast, changing the overall brightness or hue of an object’s surround induces a complementary shift in the perceived brightness or hue of the object’s color. Color contrast is thought to contribute to color constancy with changes in illumination.
A new type of simultaneous color contrast, in which changing only the variance (i.e. contrasts and saturations), but not the mean, of colors in a test spot’s surround, induces a complementary shift in the perceived contrast and saturation of the test spot’s color. Objects appear much more vivid and richly colored against low-contrast, gray surrounds than against high-contrast, multicolored surrounds.
The color appearance depends not just on the mean color of the surround, but also on the distribution of surround colors about the mean. This novel form of simultaneous color contrast is inconsistent with a variety of models of color appearance, including those based on sensitivity regulation at the receptor level, and those in which the effects of complex surroundings on color appearance can be reduced to adaptation to the illuminant or induction from a homogeneous ‘equivalent surround’. It tends to normalize the gamut of perceived colors in each visual scene and may also contribute to color constancy under viewing conditions that affect contrast.
Color Vision Deficiency
Color vision deficiency is the inability to distinguish certain shades of color. The term “color blindness” is also used to describe this visual condition, but very few people are completely color-blind. Most people with color vision deficiency have difficulty distinguishing between shades of red, yellow, and green. This is known as “red-green” color vision deficiency. It’s a common problem that affects around 1 in 12 men and 1 in 200 women.
Women make better ink technicians and quality control personnel than men!
Color vision is possible due to photoreceptors in the retina of the eye known as cones. These cones have light-sensitive pigments that enable us to recognize color. Found in the macula (the central part of the retina), each cone is sensitive to either red, green, or blue light (long, medium, or short wavelengths). The cones recognize these lights based on their wavelengths. Normally, the pigments inside the cones register different colors and send that information through the optic nerve to the brain. This enables us to distinguish countless shades of color. But if the cones don’t have one or more light-sensitive pigments, they will be unable to see all colors.
Most people with color vision deficiency can see colors. The most common form of color deficiency is red-green. This does not mean that people with this deficiency cannot see these colors altogether, they simply have a harder time differentiating between them, which can depend on the darkness or lightness of the colors.
Another form of color deficiency is blue-yellow. This is a rarer and more severe form of color vision loss than just red-green deficiency because people with blue-yellow deficiency frequently have red-green blindness, too. In both cases, people with a color-vision deficiency often see neutral or gray areas where color should appear.
People who are totally color deficient, a condition called achromatopsia, can only see things as black and white or in shades of gray. Color vision deficiency can range from mild to severe, depending on the cause. It affects both eyes if it is inherited and usually just one if it is caused by injury or illness.
Ink Matching Services
Any service that states that they will match an ink color for a screenprinter obviously does not understand the screenprinting process. They are only selling something that has no value to you as the printer. You cannot ignore the fact that the color will change only because the supplier, nor the screenprinter cannot match the color on the press that is expected by discriminating clients.
Stop chasing the pot of gold at the end of the rainbow. It does not exist and never has. It is better to simply say that you cannot guarantee a “perfect” color match but will come as close as you possibly can.
Color Vision Deficiency, https://www.aoa.org/