Color Specs for Plastics

Here’s a question for the masses–
What system do you all use for specifying colors to a manufacturer when you’re designing plastic parts?

Traditionally I’ve tried to use Pantones, but I’ve found there are a lot of limitations, particularly when it comes to shades of white and gray. For instance, I have a project that will have components coming from 3 different manufacturers (injection mold, thermoformed, and machined) and the client wants it to be white… If I just say “white,” who knows what we’ll end up with. I realize even with a specific color to match against, there will still be variability, but at least it would feel like we have some control. Pantone’s closest is Cool Gray 1C or maybe 663C, but those are not what I’m looking for, so I feel like I don’t have anything to actually spec.

I’ve heard RAL as an option, but it also only has a handful of grays. I also see Pantone has a set of chips for plastics specifically but that runs a mere $8900, so maybe I’ll wait for Black Friday… I don’t think running to Benjamin Moore and scooping up stacks off paint sample cards to mail to various manufacturers is very practical either. Anyone have any other good options for getting more color control on high-finish parts?

For production where?

Asia: It’s a crap shoot. When I spec colors, I order a Pantone sheet and send one of the cells to my supplier. Since it is available in Photoshop/Illustrator, I get the Lab color settings and send that along with the Pantone. I’ll give the supplier an acceptable ΔE, which is difference between the sample (pantone) and the molded part. Usually, 2 is an acceptable ΔE, but be careful as some color differences are more perceptable than others.

America/Europe/Japan: I’ve used RAL. It’s pretty widely understood at any big molder. They are pretty limited on colors though.

Another option might be working with a compounder to get a consistent color. Basically, they can mix resin from the manufacturer (like Sabic) with colorants and other additives. Once you have a mix with them, you could list them as your preferred supplier when sourcing and have your molder use their premixed resin. I haven’t researched it, but there is more here:

Thanks for the reply. For now it’s all US-based vendors, so that makes it a little easier for us. Good tips nonetheless, being more stringent on color selections probably wouldn’t hurt. I was hoping there was some other standard that would be easy to compare lighter shade options, but I guess that would come down to getting some samples from a resin supplier.

Have you found manufacturers generally receptive to ΔE specifications? I’m guessing that means they have some sort of color spectrophotometers or they’re ordering resin from someone who does. If that’s the case, it might be more work, but maybe they could match to a paint color placard if given enough time…

I never discussed color with NA suppliers, the marketing team decided (shudders). I would suggest call and ask them.

Color spectrometers are pretty cheap. It wouldn’t surprise me if they had one for QC purposes already.

There are two good methods - which to use depends on your relationship with the molder (meaning how much have you paid them and how much volume you do), and how much time you have.

(There are probably other methods that ‘real’ CMF designers do but I’d wager they are similar to these in intentions.)

  1. Find out what compounders are preferred by the molder and their resin suppliers. RTP was mentioned above and I’ve had good projects with them. This is how to do it (ideally). Ray mentioned RTP. RTP are good people. You ask your molder to introduce you to RTP (or compounder X), and you get on a plane and sit with their mixing experts for a day or two while they shoot plastic chips. You evaluate the chips in their color corrected booths, and make up sets of matching colors for however many resins you need. The last time I went to RTP (Winona MN, lovely place on the river), we mixed-up nylon, ABS, and polypro in a day for one single color. I’ve done a similar engagement with Clariant out of their Phoenix AZ location. The color guys are really wizards, able to add fractions of a gram of tint material to small batches of raw resin to tweak the color. However they ideally need to start with something, which brings us to #2.

  2. Find a ‘thing’ - ideally plastic of some sort - that is large enough to handle, examine, and collect spectrophotometer readings from. You make your own calibrated spectrophotometer CIELAB readings, establish your error tolerance (we use delta 1.5), and send the chunk of ‘thing’ to the molder. They will then go through #1 by themselves, sending you back chips when they have achieved their take on a good match. You can visually inspect them and then run their chips through your spectrophotometer to validate. I haven’t had much luck going straight to CIELAB as a method of communication, too much runaround for everyone, and if you had the CIELAB to begin with, you could send a sample.

I haven’t found Pantone paper swatches to be good for spectrophotometer readings. Too small and they have paper-like qualities. The plastic chips never really caught on either - and they are expensive to distribute and you never get them back. The benefit of #1 is you get back on the airplane in the evening with a book of plastic chips and the compounder provides the color data, resin pellets, or compounds to the molder.

The honorable mention method is to sit in rural mainland China, drinking hot, strong, red tea with the factory owner while he and your production representative argue in Mandarin. His workers mold sample parts, bringing them to you while you munch on the ‘organic’ peanuts farmed directly in front of the plastic factory. You hold up the brand new parts with your dreams of world color domination to the window, behind which the dull sky manages a sickly beige, and ascertain how many more molding repetitions the owner and your growing dysentery are willing to put up with. You leave the factory with color samples, and resolve to document the color ‘Qingdao Haze’ once back in front of a laptop.

I used to work in an office that was painted Qingdao Haze. Made me sick. It’s strange that they carry that Home Depot.

Maybe I’ll just simplify the process and make everything for this and future projects in Qingdao Haze

Sometimes it helps to have a “golden sample”… a sample that all the vendors can reference. IE if there is a white you want to hit in a certain product in the market, buy one for every vendor and one to have back in the office to compare to.

And then, specify the light that you are matching under i.e. 5000K, 6500K.
Also Pantone sells Lighting Indicator Stickers for both 5000K and 6500K to indicate accuracy of the light.
Get a color matching light box!

Yes, and keep the Golden Sample in a closed box or some place where it gets no light falling on it.

We have a pantone colour plastics library and purchase individual chips to send to manufacturers for reference when it is colour critical. Seems to work reasonably well. They are good at copying if there is a physical sample. Not the cheapest way. We often just use the Pantone Book for initial colour specs as it at least appears consistently understood. We have had manufacturers that havent heard of RAL (Crazy ,right?)
Specifying whites has been the biggest challenge. We ended up forking out for the Pantone tones colour wheel (whites through to blacks) and even though it was a huge rip off it has made our lives easier.

I’ve had good results with RAL for paints and powder coat, never for plastics.

I was eyeing that Pantone “tones” wheel, good to know that it’s at least useful if you do shell out the money for it. Thanks everyone for all the different ideas though. I think in many instances clients aren’t going to be willing to open their wallet for manufacturer visits and custom color blends, but for a high roller, that’s a reasonable consideration. Most of our clients aren’t as picky as I am anyways… At least knowing some different approaches I can outline options and limitations.