Why Silicone Colour Never Matches the Pantone Chip
Material Science · Anysil Silicone Co., Ltd, Panyu, Guangzhou
A Pantone chip is a surface. Silicone is a volume. Almost every colour dispute in this industry comes from that one difference - and from approving a colour in conditions the product will never see.
Meta description: A Pantone chip is a surface. Silicone is a volume. Five physical reasons the same colour code reads differently on a moulded part - plus the approval protocol and ΔE tolerance that end the argument before production starts. Slug: /blog/silicone-colour-matching Tags: silicone colour matching, Pantone silicone, LSR colour tolerance, delta E, metamerism, silicone pigment, platinum cure inhibition, colour approval
A buyer holds a chip. A factory holds a moulded part. The buyer says the part is too dark. The factory says the chip is not achievable. Both are correct, because they are comparing two different physical objects.
Ink sits on a surface: light hits it, reflects, and that is the colour. Silicone is translucent - pigment is dispersed through a polymer volume, so light enters the material, scatters between pigment particles and exits. What comes back depends on how far it travelled, how much it met, and what was behind it. Colour in silicone is therefore a function of thickness, not only of pigment.
The single most common colour dispute: a 0.3 mm trial print approved against a 1.5 mm moulded plaque. Same formulation, same pigments, two different colours - and no supplier can fix it, because the specification never said which one was the target.
Five variables that move the reading
| Variable | Effect on appearance |
|---|---|
| Wall thickness | Thicker sections read deeper and more saturated - light travels further through pigment before returning |
| Opacity / base white | Translucent silicone takes the colour of what is behind it; on dark fabric the hue shifts without a base layer |
| Surface finish | Matte scatters light and reads lighter and softer; gloss reads darker and richer. Same batch, two finishes, two approvals |
| Heat history | Cured silicone reads darker than uncured; a hotter or longer post-cure moves bulk colour, and thick parts soak longer |
| Pigment dosing | Masterbatch typically runs 0.5–5%. At a 2% dose, a 0.1% metering error is visible - pump wear and viscosity drift are colour variables |
Three of these five are set by the product, not by the supplier: thickness, opacity and finish. That is why a colour approved on a flat chip is not an approval at all. It is a starting point.
The argument that is not about colour
Two parts can match exactly under a D65 viewing booth and disagree under the warm LED in a shop. This is metamerism: different pigment combinations can produce the same reading under one illuminant and different readings under another, because their spectral curves cross rather than coincide.
It has a practical consequence - approve under at least two light sources, one of them close to where the product will actually be seen. A match that only survives the light booth will disappoint somebody in a store.
And be careful with the instrument. A spectrophotometer reading on translucent silicone depends on what is behind the sample. Measure over the real substrate, or over a defined backing - and state the illuminant, the observer angle and the instrument geometry in the specification. Two labs can both be "ΔE 0.8" and disagree, because they measured different physical situations.
What ΔE actually means
ΔE is the numeric distance between target and result. Most suppliers will quote a tolerance; very few will tell you what it looks like.
| ΔE | What a customer sees | Appropriate for |
|---|---|---|
| ≤ 1.0 | Indistinguishable to the unaided eye | Brand-critical, adjacent parts, premium goods |
| 1.0 – 2.0 | Visible only when two parts sit side by side | General consumer products |
| 2.0 – 3.0 | Noticeable in direct comparison | Internal or non-visible components |
A specification worth writing: ΔE ≤ 1.5 for visible consumer parts, ≤ 1.0 for brand colour, and batch-to-batch variation ≤ 1.0 against a retained standard - measured, not eyeballed, and with the measurement conditions named.
The failure that looks like a colour problem but isn't
Some pigments poison a platinum-cure system. Sulfur and sulfide compounds, amines, and organometallics such as tin or lead can inhibit hydrosilylation - the part comes out tacky, under-cured or patchy, and the colour is the least of the problems. Any new pigment should be checked in a small platinum batch before it goes near production.
The curing system shifts appearance too. Peroxide cure leaves acidic residues that yellow with heat and time; platinum cure produces no such by-products, which is why bright and clear colours are more reproducible on platinum.
How to approve a silicone colour, properly
Send a physical reference, not a screenshot. A Pantone code is a target, not a formula - it was never designed for a translucent volume.
State the substrate, thickness and finish at the same time. These three decide the result more than the pigment does.
Approve on a moulded plaque in the final material, final texture and final thickness. Not on paper, not on a 3D print, not on a competitor's part in a different durometer.
Write the tolerance and the method: ΔE limit, illuminant, geometry, backing, and who measures.
Keep a signed golden sample, stored dark and sealed, and require a batch colour record with each shipment.
What we ask before matching
We formulate colour into inks and into LSR, so the questions come before the mixing: which substrate, what dry film thickness or wall section, which finish, and under what light will this be judged?
Answer those four and the match is a calculation. Answer only the Pantone number and it is a negotiation - one that gets repeated at every batch, in every argument that starts with "this one looks different".
Send the target with the substrate - give us the colour reference, the material, the thickness and the finish. We will match against the part you are actually making, and tell you upfront which references are not reachable in silicone. Request a colour match
Sources: industry guidance on silicone colour variation and ΔE tolerances; technical literature on platinum versus peroxide cure and pigment-related cure inhibition; published colour-matching practice for LSR and silicone inks. ΔE bands are indicative and should be set against your own appearance standard and measurement method.