PY12 vs PY13: Diarylide Yellow Pigment Comparison

PY12 and PY13 are the two most widely used members of the diarylide yellow family. Both are disazo pigments built on a 3,3’-dichlorobenzidine (DCB) core, both sit in the same shade neighbourhood, and both are aimed at the same broad market: high-strength, cost-effective yellows for printing inks, packaging, and lower-temperature plastics. Where they diverge is in the coupling component, and that small chemistry change drives a small but commercially relevant difference in shade, tinting strength, bleed resistance, and price. If you have ever wondered why one ink house ships a “greener” yellow and another ships a “warmer” yellow when both spec sheets just say “diarylide”, the answer is almost always PY12 versus PY13.

Specifications at a Glance

When to choose PY12

PY12 is the default high-volume diarylide. The acetoacetanilide coupler gives the pigment its characteristic greener, more lemon-leaning masstone and the highest tinting strength in the diarylide family. Because the molecule is the simplest of the family, manufacturing yield is higher and the per-kilogram price comes in slightly cheaper than PY13. That price-to-strength ratio is exactly why ink houses use PY12 as the basis for process yellow recipes: when you need to lay down a clean, bright, high-coverage yellow on cost-sensitive packaging substrates, PY12 wins on grams-per-kilogram-of-ink. The tradeoff is modest lightfastness in tint (Blue Wool 3) and a tendency to bleed slightly more in plasticised systems than PY13.

If your application is process printing, publication printing, paper printing, or general purpose packaging ink, start with PY12.

When to choose PY13

PY13 is the diarylide of choice when you need a slightly warmer yellow masstone or when the printed substrate will live next to plasticisers, solvents, or moisture. The 2,4-dimethylacetoacetanilide coupler shifts the shade redder, gives the molecule slightly better lightfastness in tint, and meaningfully reduces bleed and migration in PVC-plasticised systems. The chemical resistance profile (acid, alkali, water, lime) is also a notch stronger than PY12. The tradeoffs are a small drop in tinting strength and a small premium on the per-kilogram price.

If your application is textile pigment printing, PVC-laminated packaging, washable signage, or any system where the printed yellow will sit on or under a plasticised PVC layer, PY13 is usually the better fit.

Where the difference matters

There are three application categories where the choice between PY12 and PY13 actually moves the needle:

1. Process yellow color matching. Pantone Process Yellow and Euroscale Yellow standards were originally formulated and re-formulated against PY12. Switching to PY13 in a process yellow recipe will shift the printed yellow toward red and you will fail the standard. Stick with PY12 unless the brand owner has explicitly approved a PY13-based variant.
2. Brand color packaging. When a brand specifies a custom yellow that leans warm (think mustard, golden, sunshine), formulators reach for PY13. When the brand spec leans clean and bright (think lemon, citrus, energy drinks), formulators reach for PY12. The masstone bias of each pigment is small but it is reproducible.
3. PVC masterbatch and plastisol. For low-temperature PVC pipe, calendered PVC sheet, and plastisol screen-printing inks, PY13 holds against plasticiser migration meaningfully better than PY12. If your long-term color stability matters more than your loading cost, PY13 is the safer choice.

Where the difference does not matter

For a large slice of real-world demand, PY12 and PY13 are practically interchangeable. Newsprint inks, low-end gravure, internal-use paper printing, decorative colored paper, low-spec architectural paint, and rubber compounding all happily accept either grade. In these applications the procurement team usually buys whichever AAA family yellow has the better price and stock position that month. Both pigments will deliver a strong, bright yellow that performs to specification, and both will look the same under a casual side-by-side inspection.

If your spec sheet says “diarylide yellow, AAA family, X% strength” and does not call out the specific CI number, treat PY12 and PY13 as functional equivalents and quote the cheaper of the two on the day.

Heat stability cap: when to walk away from both

Both PY12 and PY13 hit the same wall at around 200°C to 220°C of dwell heat. That ceiling is fine for PVC processing (180-200°C), low-density polyethylene blown film (180-210°C), plastisol cure (160-180°C), and almost all printing ink applications, which dry rather than melt. The wall becomes a problem when you push into HDPE injection moulding, polypropylene fibre extrusion, or engineering plastics where processing temperatures sit at 240°C, 260°C, or higher. At those temperatures the diarylide structure begins to thermally cleave, releasing 3,3’-dichlorobenzidine fragments and producing brown decomposition spots in the moulded part.

If your application is HDPE, PP, ABS, polystyrene, or higher-temperature thermoplastics, do not specify a diarylide yellow. Specify PY83 for cost-effective coverage up to roughly 260°C, or step up to PY154 benzimidazolone for premium polyolefin masterbatch with full 280-300°C heat stability and superior lightfastness. Our HDPE pigment selection guide walks through the temperature thresholds in detail.

Sourcing PY12 and PY13 from Kanani

Both pigments are manufactured in our Gujarat plant from in-house intermediate stocks, and both ship under identical commercial terms. MOQ is 25 kg for either grade, with smaller trial quantities accommodated for first-time qualification. Lead time is 7 to 10 working days from confirmed PO, and repeat orders against running stock dispatch within 3 to 5 days. Free 50-100 gram evaluation samples ship same-day for prequalification, and every consignment ships with a Certificate of Analysis, Safety Data Sheet, REACH declaration, and 24-banned-amines-free certificate. Whether you are sourcing for the Indian market or for export across our 30-plus country footprint, the spec sheet, the documentation pack, and the sales response are the same. Tell us the application, the target shade, and the binder system, and we will recommend the right grade and ship the sample.