Okay. So am I really the only one who has ever fudged the whole dye lot issue and used two different lots of yarn because the colors were the same? And I mean, only when two lots really look the same. I’m not kidding. I certainly wouldn’t risk the health and safety of my WIP by carelessly mixing non-matching dye lots. But if the two colors match, then just how important are the little numbers on the label anyway?
The above is an especially useful argument when there isn’t enough of any single dye lot to finish a project. Who would reasonably expect me to change the way I plan to spend all my free time for the next—let’s say six weeks, just because of what colors are on the shelf?
There’s always a catch, and you can find it here: what if those dye lots looked the same to me, and different to you?
Color perception is one of those tricky things. Part physics, part chemistry, part biology, part opinion. Even knitters who choose to work in strictly black and white (which, strictly speaking, aren’t colors) use color perception. (I remember my horror when I realized I accidentally bought two different colors of white for one baby blanket (bad) and didn’t realize it until the blanket was done (double bad).) The whole thing boils down to deciding when two things are the same color.
Fortunately, there is a definitive, objective answer. It’s called colorimetry—basically it’s where one scientifically measures color.
Color Basics–Skip if short on time and good with color theory
Color starts with sunlight, or white light. Light is a form of energy, and for color’s purposes, it travels in waves. Sometimes the waves are really slow (long wave length), and sometimes they are really fast (short wave length). Shorter wave lengths look red and longer wave lengths look blue-violet. In between the short and the long, we find the entire color spectrum. When sunlight is filtered through a prism, it changes the wavelengths—separates them out—and we see the rainbow.
So how is yarn colored? If every sunbeam has the entire rainbow, how do we see one color at a time? Well, prisms aren’t the only thing that separates light out into colors. Everything that has a color, which is everything we see, changes the wavelengths in light the same way that every rock on a coastline will affect the ripple pattern in the water. Instead of separating the colors out and leaving them in a rainbow like a prism, yarn will absorb some color wave lengths (think of them as the waves that wash up onto the beach) while it rejects or “bounces back” others (the waves that crash on the rocks and go straight back out to sea). Our eyes only see the colors the yarn doesn’t absorb.
So How do we see Color?
Mmmm. One of many puzzling questions. Not every one does see color. Some people are color blind (the world is black and white) and some people are color weak (they see fewer shades of gray, or of any color). But whether someone sees all the colors, some of the colors, or none of the colors, it all has to do with their eyes.
In the retina of your eye (that’s the part on the inside back wall) are special color-sensors called cones. Honestly, scientists and doctors don’t really know how they work. There is some interesting data, and some really good theories which help give a general idea, but the exact explanation is still in the future. What we do know is that there are three different kinds of cones, they measure the different wavelengths of color, and report that color to the brain. The brain then takes what your eyes have told it, and makes up its mind what color you are looking at.
Sometimes, the cones don’t work properly, and when that happens, someone’s color perception doesn’t match what color the item actually is.
The thing is, everyone has different eyes. No one has cones which are exactly identical to anyone else. So there is a very good chance that you see color just a little bit differently from everyone else. It’s not a problem anymore than having a unique fingerprint is a problem. It’s just something that makes you special.
Do You Have the Right Stuff?
First of all, color is a measurable, definable thing. There are complicated, high tech machines out in the world which measure the wavelength of a color by shining a light on it and measuring what bounces back. It’s one of the ways hardware stores match paint colors, and Pantone sells them for calibrating your computer screen. If two things bounce back the same wavelength of light, they are the same color. It’s not an opinion, it’s a provable fact.
So, if you seriously doubt your color sensing abilities, you can purchase a colorimeter for all your trips to the local yarn store. Here is an excellent article about how they work.
Note to the chemistry inclined: a colorimeter—despite what spell check wants you to believe—is NOT the same thing as a calorimeter. Calorimeters measure the enthalpy of a reaction; colorimeters measure the wavelengths of reflected colors.
The other way to confirm or negate your color doubts is to take a color perception test. Like most things, they can be found for free on the internet (here’s the link to my favorite: Test Your Color IQ). But for companies specializing in color, it is possible to purchase sophisticated tests which help minimize human error when discerning between colors.
At the Yarn Store
So about those dye lots. Well, if you have great color perception or own a colorimeter, and the two colors look the same, I say go for it. My one caveat would be to make sure they look the same under multiple light sources. Just like white shoelaces glow in the dark under black light, other colors look different depending on whether they are viewed under fluorescent, natural, or yellow light. Even perfect color perception is dependent upon what light you are seeing with, and sometimes one light will highlight a color difference which another light won’t.
With that in mind, the wise and the cautious knitter will continue to only buy yarn from a single dye lot. They will only embark on projects for which they can purchase all the yarn at one time, and when faced with the dilemma of insufficient yarn, they will choose another path entirely. Their journey as knitters will be calm, untroubled by the drama which accompanies the unknown.
But for those who are willing to play the odds with the dye lot numbers, who will eyeball the varied hues of yarn available with an unshakeable confidence in their own color matching abilities, who are willing to risk their color perception against all the nuanced lighting and opinions in the world beyond the yarn shop . . .
Let’s just say it can make for a more “interesting” project.