Black Recycled Granules: Common Uses and How to Check Quality
PlasticSetu sourcing desk · 15 Oct 2026 · 5 min read · black granules · quality checks · ash content
Walk through any recycling cluster in India and most of the granules you see will be black. That is not an accident. Black is the colour that mixed scrap naturally ends up as, and it is also the colour that hides the most variation. For many products black recycled granules are a sensible, practical raw material. For buyers, the challenge is that black can hide problems as well as colours.
This guide explains why black is so common, where black recycled granules are used, and which checks tell you whether a black lot is good quality.
Why so much recycled plastic is black
Post-consumer and much post-industrial scrap arrives in many colours. Sorting it by colour costs time and money, and some streams cannot be sorted economically at all. When mixed colours are melted together the result is usually a muddy brown or grey. Adding a small amount of black masterbatch turns that into a consistent black, which is acceptable for many products.
So black granules can be made from mixed coloured feed, from dark scrap such as black pipe or automotive parts, or from good material that was simply darkened to give a uniform colour. All three can be called "black granules", but they are not the same quality.
Where black recycled granules are used
- Recycled PP: crates, pallets, buckets, automotive under-the-bonnet and interior parts, furniture frames and garden products. See recycled PP granules.
- Recycled HDPE: non-pressure pipes, drainage products, bins and crates. See recycled HDPE granules.
- Recycled LDPE and LLDPE: garbage bags, construction film, mulch film and other film where colour is not important. See recycled LDPE granules.
Where appearance matters less than cost and basic properties, black is usually the right choice.
Carbon black: pigment and protection
Most black colour comes from carbon black. Apart from colour, carbon black helps protect plastic from UV light, which is why outdoor products are often black. But the amount and dispersion in recycled granules vary. A lot made black with very little pigment may look dark grey and show streaks in the moulded part.
If UV resistance matters for your product, do not assume the recycled granules provide it. Ask the supplier, or plan to add your own masterbatch and test the result.
Filler and ash checks
Black hides filler. Calcium carbonate or talc added to bring cost down is not visible in black granules the way it might be in natural ones. Filler is not always a problem, since many products use filled material by design, but you should know what you are paying for.
The simplest check is ash content: burn a weighed sample and weigh what remains. Carbon black burns off, while mineral fillers, sand and dirt remain as ash. Agree an ash target and tolerance with your supplier, and test each lot or at least the first few.
Density as a quick screen
Density is an easy, cheap check that catches several issues at once:
- Unfilled PP is around 0.90 to 0.91 g/cm3, so it floats in water.
- LDPE is about 0.91 to 0.94 g/cm3 and HDPE about 0.94 to 0.97 g/cm3; both also float in water.
- Granules that sink in plain water are likely filled, or contain heavier polymers such as PVC, PET or ABS.
A float test in a bucket of water will not tell you exactly what is wrong, but it will tell you when to ask more questions. Follow up with a proper density test and polymer identification if needed. Our guide on how to identify plastic types covers simple methods.
Other quality points to check
- MFI: ask for a value per lot. Mixed feed often gives wide MFI variation. See how to check MFI.
- Moisture: check visually and, if possible, with a moisture analyser, particularly if the material was washed.
- Odour: a strong smell can point to contamination or degraded material.
- Granule shape and size: uneven granules and fines can cause uneven feeding.
- Gels and unmelts: for film, press a thin sheet or run a trial to see them.
Buying black granules through PlasticSetu
When you post a requirement, give the polymer, end product, MFI range, whether filler is acceptable, any ash or density limits you work to, and monthly quantity. PlasticSetu's sourcing desk shares it with matching verified suppliers, collects quotations and arranges samples so you can test before ordering. Get quotes to start.