White masterbatch looks like a commodity and is quietly one of the easiest products in this industry to buy badly. Two grades can both say “70% TiO₂” and perform very differently in your part — different opacity at the same dosage, different yellowing after a year outdoors, different screen-pack life.
Here is what actually determines whether a white masterbatch is right for you, and what to ask a supplier before the first order.
The pigment is the product
Almost all white masterbatch is titanium dioxide in a carrier. What you are really buying is which TiO₂, how much of it, and how well it has been dispersed.
Rutile or anatase
Two crystal forms, and the difference matters more than most datasheets suggest.
Rutile has a higher refractive index, so it gives more opacity per unit weight, and it is far more resistant to photocatalytic degradation. For anything that sees sunlight, rutile is the answer.
Anatase is softer and less abrasive on tooling, slightly bluer in tone, and significantly more photoactive — under UV it can catalyse breakdown of the surrounding polymer, causing chalking and embrittlement.
For outdoor parts, rutile is not a preference, it is a requirement. We cover the mechanism in titanium dioxide in plastics: rutile vs anatase.
What to ask: which crystal form, and is it surface treated? Modern rutile grades carry inorganic and organic surface treatments that improve dispersion and durability. “TiO₂” on a datasheet is not a specification.
Loading is not opacity
A 70% loading sounds better than a 50% loading, and it costs more. But opacity in your finished part is a function of how much TiO₂ ends up there, how well dispersed it is, and the part thickness — not the percentage in the bag.
A well-dispersed 50% white at a higher let-down ratio can out-perform a poorly dispersed 70% at a lower one, and cost less per part. Compare cost per finished part at equal opacity, never cost per kilogram.
What to ask: at what let-down ratio does this grade reach my required opacity in my polymer at my wall thickness? A supplier who will run that trial is worth more than one who quotes the lowest rate per kilo.
Dispersion: where white masterbatch goes wrong
TiO₂ is abrasive and it agglomerates. Under-dispersed white gives you:
- Lower opacity than the loading implies — agglomerated particles scatter less light than the same mass well distributed
- Screen-pack blockage and rising filter pressure
- Specks and surface defects, especially visible against a white background
- Tool wear, faster with poorly dispersed abrasive pigment
The check is filter pressure value testing — a known mass pushed through a fine screen, with the pressure rise recorded. A supplier who controls dispersion will offer this number. One who does not will talk about quality generally.
Yellowing, and what actually causes it
White parts yellowing is the most common long-term complaint, and the colourant is often blamed when it is not the cause.
The real causes, roughly in order of frequency:
- Thermal degradation of the base polymer during processing — too hot, too long, or a stagnant spot in the tool
- Photo-oxidation in service, especially where an anatase grade was used outdoors
- Additive interactions — some antioxidants and UV stabilisers discolour under certain conditions
- Regrind content carrying accumulated thermal history
- The masterbatch itself, usually via an unsuitable carrier
Adding optical brightener masks early yellowing rather than preventing it, and brighteners themselves degrade — which can leave the part worse after two years than it would have been. We cover both in why white plastic yellows and optical brighteners in plastics.
What to ask: what is in this grade besides TiO₂ and carrier, and is there a brightener in it? You want to know before you commit, not after a field return.
Carrier compatibility
The carrier polymer has to suit your base resin and your process.
- A PE-carrier white in a PP part is common and usually fine, but it affects clarity and can affect weld-line strength
- In PET, moisture sensitivity and the processing window make carrier choice much tighter — see PET preform and bottle masterbatch
- In engineering polymers like ABS, PC and nylon, thermal stability of the carrier becomes the limiting factor — see colouring ABS, PC, nylon and POM
A supplier offering one white for every polymer is offering convenience. Sometimes that is fine. For a demanding part it is not.
Compliance, by end market
White masterbatch ends up in food packaging, toys, pipes and medical components more often than almost any other grade, so the documentation question is live.
| Application | What to ask for |
| Food contact | FSSAI, plus the applicable IS specification for the polymer |
| Toys | EN 71-3 heavy-metal migration, IS 9873 |
| Potable water pipe | The relevant IS for the pipe plus food-contact-grade colourant |
| EU export | REACH, and RoHS where there is electrical function |
Ask for a declaration naming your grade. A company ISO certificate does not answer this question.
The questions worth asking a white masterbatch supplier
- Rutile or anatase, and what surface treatment?
- At what let-down ratio does this reach my opacity in my polymer at my thickness?
- What is the filter pressure value for this grade?
- Is there an optical brightener in it?
- What carrier, and why that one for my resin?
- Can you give me a grade-level compliance declaration for my end market?
Where the cheapest quote usually loses
White is the grade where price comparison most often misleads, for three reasons.
Dosage. A cheaper white at a higher let-down ratio can cost more per part. Normalise before comparing.
Hidden process cost. Poor dispersion shows up as screen changes, scrap and downtime, none of which appear on the masterbatch invoice.
Field cost. An anatase grade in an outdoor part is cheaper on day one and expensive in year two.
Talk to us
We manufacture white masterbatch on our own lines at Vasai under ISO 9001:2015, using rutile grades for durable and outdoor applications, and we verify dispersion by filter pressure value rather than by assurance.
We will not quote a loading into a blog post, because the right loading depends on your polymer, your wall thickness and the opacity you actually need.
Send us your polymer and grade, your process, your wall thickness and the opacity you are trying to reach, and we will propose a grade and a trial you can run on your own line. Related: white masterbatches, colour masterbatches, packaging, household, toys.
Frequently asked questions
What is white masterbatch made of?
Titanium dioxide pigment dispersed in a carrier polymer, usually with dispersing aids and sometimes additional additives. The TiO2 crystal form, its surface treatment, the loading and the quality of dispersion are what distinguish one grade from another.
Should I use rutile or anatase titanium dioxide?
Rutile for anything exposed to sunlight, and for most applications generally. It has a higher refractive index, so more opacity per unit weight, and it is far more resistant to photocatalytic degradation. Anatase is softer and less abrasive but significantly more photoactive, which causes chalking and embrittlement outdoors.
Does a higher TiO2 loading mean better opacity?
Not necessarily. Opacity in the finished part depends on how much TiO2 ends up there, how well it is dispersed and how thick the part is. A well-dispersed 50% grade at a higher let-down ratio can beat a poorly dispersed 70% at a lower one, and cost less per part.
How do I compare white masterbatch quotes properly?
Compare cost per finished part at equal opacity, not cost per kilogram. Establish the let-down ratio each grade needs to reach your opacity in your polymer at your wall thickness, then do the arithmetic.
Why has my white plastic turned yellow?
Most often thermal degradation of the base polymer during processing, photo-oxidation in service, additive interactions, or accumulated thermal history in regrind. The masterbatch is a less frequent cause than it is blamed for, though an unsuitable carrier or an anatase grade outdoors will do it.
Should white masterbatch contain an optical brightener?
Only deliberately. Brighteners mask early yellowing rather than preventing it, and they degrade over time, which can leave a part looking worse after a couple of years. Ask whether one is present before committing to a grade.
Is white masterbatch suitable for food packaging?
It can be, but suitability depends on the grade. Ask for a declaration naming your grade against FSSAI and the applicable IS specification for your polymer. A company ISO 9001 certificate does not answer the food-contact question.
What causes specks in white plastic parts?
Undispersed pigment agglomerates, contamination in regrind, degraded material from a stagnant spot in the barrel or tool, or carbon from a previous dark colour that was not fully purged. Specks are far more visible against white, which is why white often exposes a dispersion problem first.
Buying masterbatch for this application?
We manufacture in Vasai and supply converters across India. Tell us the polymer and the process, and we will come back with a grade and a price.