Butyl Compound Color Customization: Grey, White & Custom Pigments

Walk through any sealing-materials warehouse and almost every butyl compound you see will be black. That is not a styling decision or a cost shortcut — it is the single most effective piece of engineering in the formulation. Carbon black is simultaneously a reinforcing filler, a UV absorber, and the cheapest way to get both. When a customer asks for grey, white, or a brand colour, they are asking us to remove that triple-duty ingredient and replace its functions separately.

Garmy's butyl compound is offered in black, grey, or custom colour, and colour requests are common in three situations: architectural sealing where the bead stays visible against a light façade, electronics and appliance assemblies where a black smear reads as contamination on the line, and OEM programmes where a colour is used as a poka-yoke to prevent the wrong material being applied. All three are legitimate, but each carries the same physics bill.

Here is what carbon black is actually doing before you take it out:

• UV absorption — It intercepts ultraviolet energy at the surface and dissipates it as heat before it can break polymer chains. No white or pastel pigment matches this; titanium dioxide scatters and reflects some UV but is far less absorbent, and certain TiO₂ grades are photocatalytic, which can actively accelerate surface degradation unless a coated, weather-durable grade is used
• Reinforcement — Fine-particle carbon black raises cohesive strength and sag resistance. Replacement mineral fillers such as calcium carbonate or talc extend volume but reinforce less, so the formulation has to be rebalanced to hold the same body
• Opacity and dirt masking — Black hides construction dust, handling marks, and edge contamination. Light-coloured beads show every fingerprint and every airborne particle that lands during cure-free installation
• Cost — Carbon black is inexpensive. Titanium dioxide and stable organic/inorganic colour pigments are considerably more expensive per kilogram, and they are typically needed at higher loading to achieve full hiding power

The honest summary for a specifier: a coloured butyl compound is entirely feasible and Garmy produces it, but it should be treated as a protected-joint material. If the bead will be covered by flashing, trim, a cover plate, or an overlapping panel, colour costs you very little in service life. If the bead is fully exposed to direct, continuous sunlight, black remains the correct engineering answer and any colour choice needs a documented UV strategy behind it.

Replacing carbon black is not all-or-nothing. In practice there is a spectrum, and most successful colour projects land somewhere in the middle rather than at pure white. Grey compounds, for example, retain a reduced carbon black loading blended with white pigment, which preserves a meaningful share of the UV protection while delivering a visually light bead. That is why grey is by far the most commonly requested non-black option and the easiest to support in volume.

Beyond UV, two colour-specific failure modes deserve attention in qualification, because neither shows up in a standard peel or heat-resistance test:

1. Discolouration and yellowing — Light compounds show oxidative yellowing that a black compound would simply hide. Antioxidant selection and avoidance of certain process oils matter far more in a white formulation than in a black one
2. Substrate staining — Plasticizer migration into a porous or painted substrate produces a visible halo. On a light-coloured bead against a light façade this becomes a warranty conversation, so a non-bleeding plasticizer system should be specified from the start
3. Batch-to-batch colour variation (ΔE) — Rubber compounding is not paint mixing. Agree an acceptable ΔE against a physical master swatch, and confirm whether the assessment is visual or instrumental, before the first production lot
4. Heat and process excursions — Some organic pigments shift shade after a paint-oven cycle. If the assembly passes through elevated temperature, qualify the colour after that thermal history, not before

Note that colour changes the pigment package, not the fundamental grade architecture. Garmy's published compound performance envelope — service range −40°C to +120°C, tape grades to 110°C — is set by the polymer and filler system. The specific published grade values (HY-1 peel 81.07 N/cm, HY-2 58.91, CN-1 62.45, CN-FR 81.07 with UL94 V-0, SD-1 42.82, S-3 36.86) apply to the standard formulations; a pigmented variant is requalified on its own test data rather than inheriting these numbers by assumption.

If you need a light-coloured bead without giving up sealing performance, start from Garmy's grey compound options rather than jumping straight to white.

Technically, almost any colour is achievable. Commercially, the constraint is that a pigmented butyl compound is a dedicated production run. Internal mixers and downstream extrusion or calendering lines have to be purged when switching from black to a light colour, and that purge — not the pigment itself — is usually the dominant cost driver behind minimum order quantities on custom colours.

What that means for your project plan:

• MOQ is higher for custom colours than for standard black — Black runs continuously; a colour run must be scheduled, purged into, and purged out of. Grey generally carries a lower MOQ than white or a brand-specific colour because it is requested more often
• Lead time includes a colour-approval loop — Expect an initial lab-scale colour trial, a physical swatch or plaque for your sign-off, and only then a production lot. Building that approval cycle into the schedule up front prevents it appearing as a surprise delay later
• Repeat orders are cheaper and faster than the first — Once the pigment package and master standard are locked, subsequent lots are a normal scheduling exercise. The first order carries the development effort
• Packaging is unchanged — Coloured compound ships in the same 20 kg PE bag or 1,000 kg pallet formats as the standard product
• Forecast matters more than for black — A rolling forecast lets a colour run be batched efficiently. Sporadic small pulls against a custom colour are the most expensive way to buy it

To keep a colour project on schedule, supply the following at enquiry stage rather than after the first sample:

1. A colour reference — RAL, Pantone, or ideally a physical master sample. A screenshot or a hex code is not a manufacturable reference for a filled rubber compound
2. The acceptance criterion — Visual match under a stated light source, or an instrumental ΔE tolerance. State which one governs
3. Exposure class — Interior, covered exterior joint, or fully exposed. This determines whether the pigment package needs weather-durable grades
4. Annual volume and call-off pattern — This drives MOQ and pricing more than any other single input
5. Any regulatory constraint — Heavy-metal-free pigment requirements, automotive interior VOC and odour limits, or flame-retardant compatibility if a CN-FR-type UL94 V-0 grade is involved

Garmy has been compounding butyl since 1999 at a 4,200 m² plant in Eumseong, Chungbuk, producing over 3,400 tonnes annually under IATF 16949, ISO 9001 and ISO 14001, with three registered patents, a Hyundai SQ mark, and exports to six countries. That production base is what makes a scheduled colour run practical rather than a one-off favour — and every lot, coloured or black, ships with a Certificate of Analysis.

Send us your colour reference and annual volume and we will come back with a realistic MOQ, lead time, and approval plan.

Q: Can you supply butyl compound in white?

A: Yes — Garmy's butyl compound is available in black, grey, or custom colour, including white. The engineering caveat is UV: white pigment does not replace carbon black's ultraviolet absorption, so a white compound should be specified for interior use or for exterior joints where the bead is covered by flashing, trim, or an overlapping panel. For a fully exposed exterior bead in direct sun, black remains the correct choice.

Q: How much UV resistance do I actually lose going from black to grey?

A: Less than going to white. Grey compounds retain a reduced carbon black loading blended with white pigment, so a meaningful share of the UV absorption is preserved. This is why grey is the most practical light-colour option and the one we recommend when the requirement is "not black" rather than "specifically white". The exact retained performance depends on the loading, so it is confirmed on the actual formulation during qualification.

Q: What is the minimum order quantity for a custom colour?

A: It is higher than for standard black, and it depends on the colour. The driver is not pigment cost but the dedicated production run — mixing and downstream lines must be purged when switching from black to a light colour. Grey typically carries a lower MOQ than white or a brand-specific colour. Send your target colour and annual volume and we will quote a specific MOQ rather than a generic figure.

Q: How do you control colour consistency between lots?

A: Against an agreed physical master standard. Before the first production lot we ask you to sign off a swatch or plaque, and we ask you to state whether acceptance is a visual match under a defined light source or an instrumental ΔE tolerance. That decision needs to be made up front — resolving it after a delivery has arrived is the most common cause of colour disputes.

Q: Does adding pigment change the mechanical or temperature performance?

A: The polymer and filler system sets the performance envelope — Garmy compound grades operate from −40°C up to 120°C, tape grades to 110°C — and a pigment change does not move that envelope by itself. However, because carbon black also acts as a reinforcing filler, a light-coloured formulation is rebalanced to hold comparable body and cohesive strength. Published grade values such as HY-1 at 81.07 N/cm peel apply to the standard formulations, so a pigmented variant is qualified on its own test data rather than assumed to inherit them.

Ready to source the right butyl material for your application?