Haze and Clarity Measurement: ASTM D1003, ISO 14782 and the 9 Additive Groups That Change the Numbers

Haze is the share of the light passing through a plastic that is scattered more than 2.5 degrees away from the incident beam, and it is measured as a percentage under ASTM D1003-21 or ISO 14782. A clear compound and a milky one can carry the same luminous transmittance, so which number actually decides whether a part looks clear? Haze decides it, together with clarity, the narrow-angle counterpart below the same 2.5 degree boundary, while luminous transmittance records only how much light gets through at all. Above 30 % haze the question changes, because ASTM D1003 then treats the material as diffusing rather than transparent.

Haze is one of the few properties a formulator moves almost entirely through plastic additives, and it moves in both directions: one family exists to lower it and eight others raise it as a side effect. Those nine groups, in the order this page keeps throughout, are clarifying agents, particulate nucleating agents, antiblock minerals, slip agents, mineral fillers, pigments and colorants, impact modifiers, lubricants and processing aids, and the barrier and oxygen-scavenger additives used in PET.

This page sets out the three numbers that come off one specimen, the two ASTM D1003 procedures and their non-equivalence with the ISO methods, the 30 % boundary where a haze percentage stops meaning anything, the five physical causes of haze, the direction and loading window of all nine additive groups, the neighbouring optical tests and a 7-step procedure for finding the cause of haze in a clear compound.

Four figures that fix the scale of the haze question

• 2.5 degrees: the scattering angle that separates haze from clarity.
• 30 %: the haze value above which a material counts as diffusing and goes to ASTM E2387 instead.
• 200 ppm: the lowest clarifying concentration recorded for a benzenetrisamide in isotactic polypropylene.
• 2.2 % haze at 1 mm: the lowest haze ADEKA reports for a clarified polypropylene, against a market low of 3.2 %.

What Is Haze in Plastics?#

Haze in a plastic is wide-angle light scattering: the fraction of the transmitted light that leaves the specimen more than 2.5 degrees off the incident beam, which is why a hazy part looks milky and why print behind it loses contrast. The eye reads that scattering as milkiness; the instrument reports it as a percentage of the transmitted light. ASTM D1003-21 is written for exactly this property, covering the "specific light-transmitting and wide-angle-light-scattering properties" of planar sections of materials such as essentially transparent plastic, which keeps both transparent and translucent plastics inside the method. Haze is not the only number on an optical data sheet, so how does it differ from clarity and from luminous transmittance?

Haze vs clarity vs luminous transmittance#

Haze, clarity and luminous transmittance separate by the angle at which light leaves the specimen: haze counts the light scattered more than 2.5 degrees off the beam, clarity counts the narrow-angle scattering below that boundary, and luminous transmittance counts all the light that gets through at all. Haze is reported as the percentage of the transmitted light scattered beyond that 2.5 degree boundary, which is why a specimen can transmit most of the light falling on it and still look hazy. A bright specimen and a clear specimen are not the same thing, and a data sheet giving one of the three numbers has answered one of three questions.

Table 1. The three optical numbers that come off one specimen

Clarity is the narrow-angle counterpart of haze. The knowledge base records no standard designation and no instrument geometry for it, so this page names neither.

Haze and luminous transmittance are reported together because one standard covers both, which is why the title of ASTM D1003 names them side by side. The same compound can give two different haze numbers on two different plaques, so what else does the number depend on?

Why haze depends on thickness#

Haze rises with thickness because every additional millimetre of wall gives the light more scattering centres to pass, which is why ASTM D1003 applies to planar sections and why a haze value quoted without its thickness cannot be compared with anything. The 2.2 % haze at 1 mm that ADEKA reports for its clarified polypropylene and the haze of a 25 µm blown film are two numbers on two different scales, and nothing useful follows from putting them next to each other.

A specification inherits the same rule. A haze limit that names neither the thickness it applies to nor the measurement procedure that produced it is incomplete, because a supplier can meet it on a thin plaque and miss it on the real wall.

What haze value counts as clear?#

One boundary is set by the standard and the rest is set by the product: above 30 % haze a material is no longer treated as transparent at all and is measured to ASTM E2387 instead, while the pass mark for a clear container, a film or a lens is whatever the specification for that part says. No typical haze value exists for any polymer in the sourced record, and the one published figure is a supplier claim, ADEKA's 2.2 % haze at 1 mm for a clarified polypropylene against a market low of 3.2 %. PMMA transmits 92 % of visible light at 3 mm, which is a luminous transmittance value and not a haze value.

How Haze Is Measured: ASTM D1003 and ISO 14782#

Haze is measured by sending a parallel beam of light through a flat specimen and separating the light that continues straight on from the light that scatters wide, which ASTM D1003-21, Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics, does in two procedures. The standard provides both procedures for the same pair of properties: procedure A uses a hazemeter, described in Section 5, and procedure B uses a spectrophotometer, described in Section 8.

One structural fact comes from the standard's own significance-and-use text: the specimen is necessarily placed at the entrance port of the sphere in order to measure haze. The two procedures use different instruments, so do they give the same number?

Procedure A: the hazemeter#

Procedure A is the dedicated-instrument route: a hazemeter sends a parallel beam through the specimen at the entrance port of an integrating sphere and compares the total transmitted light with the part of it that scatters more than 2.5 degrees wide. That is what a haze meter is and what it does.

Procedure A readings are normally slightly higher and slightly less variable than procedure B readings on the same specimen. That single sentence is the most useful thing a laboratory can know before it compares its own data with a customer's, because a gap between two laboratories can be an instrument difference, not a material one. ASTM D1003 records the behaviour without ranking the two procedures.

Procedure B: the spectrophotometer#

Procedure B uses a spectrophotometer fitted with an integrating sphere, which measures haze and luminous transmittance on the same specimen that the laboratory uses for colour, and returns wavelength-resolved data the hazemeter does not produce. A laboratory already running colorimetry has the instrument, which is the usual reason procedure B is chosen.

The two procedures are not interchangeable numerically. A specification that names a haze limit therefore names three things, not one: the limit, the specimen thickness it applies to, and the procedure that produced it. Two suppliers quoting the same haze figure from different procedures have not quoted the same result.

Why ASTM D1003 and the ISO methods are not equivalent#

ASTM D1003 and the ISO methods are not interchangeable, and the ASTM standard states it in its own Note 2: the test method is not equivalent to ISO 13468-1 or to ISO 14782. The structural reason is a split. ISO puts haze in ISO 14782 and total luminous transmittance in ISO 13468-1, two standards for two properties, while ASTM D1003 covers both in one. A data sheet quoting haze per ISO and a data sheet quoting haze per ASTM are therefore not directly comparable, even before thickness and procedure enter the comparison.

Table 2. The four optical-scattering standards this page names

ASTM D1003 Note 2 records the non-equivalence using the draft designation ISO/DIS 14782. No ISO edition year is given here because the knowledge base holds none.

Above 30 % Haze: Diffusing Materials and ASTM E2387#

Above 30 % haze a plastic is no longer treated as transparent: ASTM D1003 itself calls such a material diffusing and sends it to Practice ASTM E2387 instead, which is the point at which a haze percentage stops being a useful quality number. The method is written for essentially transparent plastic, and a milky sheet is outside that scope rather than at the bad end of it.

High haze is not always a defect. Lighting covers, display panels and luminaire optics are specified to scatter light, and in those products a haze value far above 30 % is the specification being met rather than missed. The additives that do it deliberately are the light diffusers for polycarbonate and PMMA, selected for the scattering a clear compound spends nine additive groups trying to avoid. No numeric haze range is recorded for diffuser compounds.

What Makes a Plastic Hazy? Crystals, Particles, Gels and Surface Roughness#

A plastic is hazy for 5 reasons, and every one of them puts a structure roughly the size of the wavelength of visible light in the path of the beam. The five causes, in the order a formulator meets them, are listed below.

• Crystalline superstructures in a semi-crystalline polymer, which is why industrial polypropylene at about 30 to 60 % crystallinity is hazy while amorphous polycarbonate, PMMA, polystyrene and rigid PVC have nothing of the kind to scatter light.
• Dispersed particles whose refractive index differs from the matrix, from antiblock minerals and mineral fillers to pigment agglomerates and rubber domains.
• Gels, fisheyes and unmelted material, from degraded or crosslinked polymer, un-melted resin or concentrate, or a masterbatch dispersed with too little energy.
• Additive that has migrated to the surface, the slip-agent bloom and lubricant exudation case, and the reason a film can leave the line clear and be hazy a week later.
• Surface roughness, from the die, the mould surface, the chill roll or plate-out deposited on the tool.

Two of those five causes sit on the surface and three sit in the bulk, and that split is the first branch of every haze investigation, because the two groups need different fixes: cleaning a tool does nothing for a crystallization problem, and a clarifier does nothing for a die deposit. The commonest of the bulk causes, gels and fisheyes in plastic film, has additive causes of its own. No numeric split between surface and internal haze is recorded, so the distinction is resolved by comparing a cut face with the skin rather than by a measurement.

Clarity in a semi-crystalline polymer is a crystallization problem before it is an optics problem, and polymer crystallization and nucleation sets out how additives control it. A formulator reaches the same five causes from the other direction, through the additive package, so which additives move haze, and in which direction?

How 9 Additive Groups Change Haze and Clarity#

Nine additive groups change the haze of a plastic, and only one of them exists to lower it: clarifying agents cut haze by design, while particulate nucleating agents, antiblock minerals, slip agents, mineral fillers, pigments and colorants, impact modifiers, lubricants and processing aids, and the barrier and oxygen-scavenger additives used in PET all raise it as a side effect of doing something else. Table 3 gives the direction, the named grades, the loading in the unit its source uses and the host polymer for each of the nine.

Table 3. How 9 additive groups change haze and clarity

Loadings are supplier technical-data-sheet ranges, study values or FDA maximum use levels, labelled per row. FDA caps are legal maxima, not recommended dosages. Trials on the actual compound decide the final level. Study sources: Kristiansen et al., Macromolecules 36 (2003) 5150; Blomenhofer et al., Macromolecules 38 (2005) 3688; Van Essche et al. 2000.

1. Clarifying agents: the only additives that exist to cut haze#

Clarifying agents are the one additive group designed to lower haze: they dissolve in the polypropylene melt and crystallize on cooling into a nanofibrillar network that multiplies the number of crystal nuclei until the crystalline superstructures are smaller than the wavelength of visible light and stop scattering it. The named grades are sorbitol acetals such as DMDBS (Millad 3988) and Millad NX 8000, benzenetrisamides such as Irgaclear XT 386 and phosphate salts such as NA-21, all of which act on crystallization and therefore do nothing in an amorphous polymer.

Ultra-clear polypropylene once needed 3,000 to 4,000 ppm of clarifier, a loading Milliken records for the earlier generations, and the three chemical families of clarifying agents for plastics are compared grade by grade on the family hub, which also carries the clarifier selection and haze troubleshooting guide. Kristiansen et al. at ETH Zürich reported in Macromolecules (2003) that DMDBS gives its largest crystallization-temperature gain and its lowest haze between 0.2 and 1 wt%, and Blomenhofer et al. reported in Macromolecules (2005) that a benzenetrisamide clarifies isotactic polypropylene at a weight fraction of 0.0002, that is 200 ppm, the lowest effective clarifying concentration on record. Irgaclear XT 386 is recommended at 150 to 200 ppm, and more clarifier is not more clarity: above 1 wt% DMDBS the optics get worse and above 2 wt% the system separates into two liquid phases.

A clarifier works only if the melt dissolves it first. Traditional sorbitol grades need about 220 °C in polypropylene and MDBS at 0.4 wt% about 210 °C, and they dissolve only to a few thousand ppm at most, as Horváth, Menyhárd et al. at BME Budapest showed in RSC Advances (2014). A melt below the dissolution temperature gives no clarity at any loading, the commonest failure in clarified polypropylene and the reason step 4 below checks melt temperature first.

2. Particulate nucleating agents: stiffness without clarity#

A nucleating agent that stays particulate in the melt raises the crystallization temperature, the stiffness and the output rate of a polypropylene part without making it any clearer, and talc, the cheapest of them, raises haze instead. Talc, sodium benzoate, Hyperform HPN-68L and NA-11 all work as insoluble particles rather than as a dissolved and recrystallized network, which is the whole difference from a clarifier. The best commercial polypropylene nucleators reach 60 to 70 % on the self-nucleation efficiency scale of Fillon, Lotz, Thierry and Wittmann (Journal of Polymer Science B, 1993), a figure about crystallization kinetics and not about optics.

A data sheet promising nucleation is therefore not promising clarity, and the two effects are measured by two different tests: the DSC cooling scan to ISO 11357-3 for the crystallization temperature, and ASTM D1003 for haze. Reading one as evidence of the other is the usual misreading of a nucleator data sheet.

3. Antiblock minerals: the refractive-index trade-off#

Antiblock minerals raise haze for the same reason they work: the particle has to stand above the film surface to break the contact between two layers, and anything standing in the light path scatters it. The mechanism is surface micro-roughness, which reduces contact area and van der Waals adhesion between film layers, so the benefit and the haze penalty share one geometry.

Table 4. Antiblock minerals and the clarity cost of each

Dosage windows are trial ranges from Ampacet, Van Essche et al. (2000) and published film studies, not grade recommendations. Refractive indices come from the substance records in the knowledge base. No refractive index is given for the polymers themselves because none is recorded.

Four particle properties set the trade-off between blocking and clarity, and they are listed below.

• Refractive index, where a value close to the polymer costs least clarity, as with diatomaceous earth in polyethylene.
• Particle size and top cut, where a top cut reaching 44 µm in a 25 µm film protrudes and scatters.
• Particle shape, where irregular porous particles give the needed roughness at a lower loading than blocky ones.
• Loading, where a mineral needing 2,500 to 20,000 ppm costs far more clarity than one that works at 1,000 to 1,500 ppm.

The lowest refractive index and the lowest effective loading in the group both belong to synthetic amorphous silica in plastics, which also interferes most with the rest of the package: silica adsorbs antistats and slip additives and retards their migration, and erucamide with silica lowers the coefficient of friction in polypropylene more than either alone, because the erucamide adsorbs on the antiblock. Antiblock is always a two-number decision, blocking against haze.

4. Slip agents: the bloom that hazes film days after extrusion#

Slip agents haze film by leaving it: erucamide and oleamide at 500 to 1,200 ppm migrate out of the bulk and build a layer on the surface, and because that bloom reaches most of its effect in 24 to 48 hours and settles only after 7 to 10 days, a reel that left the line clear can fail a haze check a week later. Antiblock, slip bloom and plate-out are the three surface mechanisms that raise haze after the part has left the line, and the slip case is the only one that develops on its own schedule.

How fast an additive reaches the surface is set by its solubility in the polymer and its diffusion coefficient, the mechanism behind all blooming and exudation in plastics and the reason the same 0.05 to 0.12 wt% behaves differently in LDPE and in LLDPE. A haze result on film is therefore meaningful only with the time since production recorded next to it, exactly as ASTM D1894-24 requires for the coefficient of friction.

5. Mineral fillers: haze by volume#

A filled compound is not a hazy compound, it is an opaque one: the calcium carbonate that costs a film a little clarity at 2,500 ppm sits at 20 to 40 % in a filled polypropylene, two orders of magnitude higher and far past the 30 % haze boundary where a haze percentage stops meaning anything. Talc runs up to 40 wt% as a filler in the same polymer.

The refractive indices do not change between the two roles: blocky calcite at 1.6584 and plate-shaped talc at 1.58 scatter the same way at 2,500 ppm and at 20 %, and only the number of scattering centres differs. Calcium carbonate at that loading is part of a package, and the package around it is set out under additives for polypropylene.

6. Pigments, colorants and opacifiers: haze on purpose#

Titanium dioxide is the clearest case of haze on purpose: its refractive index is so far above any polymer matrix that a crystal of about 220 nm scatters visible light more efficiently than anything else in the formulator's toolbox, which is the whole point of a white masterbatch. Pigments and colorants for plastics are the one group whose light scattering is the specification rather than the side effect. Titanium dioxide is listed in 21 CFR 178.3297 with no numeric limit and carries FCM No 610 under Regulation (EU) No 10/2011 with no specific migration limit.

A pigment meant to tint without clouding fails when it is not dispersed. An agglomerate scatters where a single particle would not, which is why a tinted clear compound is judged on dispersion testing of pigments and masterbatch as well as on haze, with microdispersion rated from 1 to 5, 1 being best, on about 1.5 mil polyethylene film and reported per lot.

7. Impact modifiers: clarity by refractive-index matching#

A clear impact-modified compound keeps its clarity by refractive-index matching: the rubber domains stay in the compound and stay large enough to toughen it, and they stop scattering only because their apparent refractive index is tuned to the matrix, as with a methacrylate-butadiene-styrene modifier at refractive index 1.535 in PVC recorded in US Patent 5,614,589. No loading is recorded for that clear-PVC case, so none is given.

High-impact polystyrene makes the rule memorable by failing it: its optimum rubber particle size can run 2 to 5 µm, squarely inside the light-scattering size range, which is why toughness and clarity are normally traded against each other. Index-matched methacrylate-butadiene-styrene is one layer of a clear rigid compound, and the rest of the package sits under additives for PVC.

8. Lubricants, processing aids and plate-out#

The two lubricant classes act on clarity in opposite directions: an internal lubricant is polar, compatible with PVC and keeps transparency without exuding, while an external lubricant is mostly non-polar, paraffin or polyethylene wax, sits between the melt and the metal, prolongs fusion, and causes haze and exudation as soon as it is over-dosed. The recorded package for clear rigid PVC injection moulding is hydroxyl glycerol ester at 0.7 to 1.0 phr plus complex ester at 0.3 to 0.6 phr, a Struktol formulation designed around transparency.

Plate-out carries the second mechanism. Die drool, also called die lip build-up or die plate-out, is the unwanted spontaneous accumulation of extruded melt on the open faces of the die, driven by the negative pressure at the die exit edge. Its contributors include the low-molecular-weight fraction of multimodal polyethylene, hexane extractables, volatile stabilizers, metallic stearates in Ziegler-Natta polyolefins and the interaction between polymer processing aids and inorganic pigments. Additive deposited on the tool transfers its roughness to every part that follows, so the haze is a tooling problem with an additive cause.

9. Barrier and oxygen-scavenger additives in PET#

Every additive that improves the barrier of a PET bottle costs it clarity, which is why oxygen-scavenger suppliers market haze reduction as a product feature: Avient positions Amosorb 4020G on up to 50 % less haze than the grades before it and on halving the b* shift. The recyclability bodies cap the loading for the same reason, and the European PET Bottle Platform design guidelines limit PA-MXD6 to 5 wt% in clear PET bottles and 6 wt% in colored or opaque ones. Reheat additives add a third constraint, since they sit in the APR "Requires Testing" category and can turn flake dark or yellow, so a clear bottle carries three optical constraints at once, all part of the package under additives for PET resin.

Haze, Gloss, Yellowness and Color: Which Optical Test Answers Which Question#

Seven questions sit on a clear-plastic data sheet and each one has its own test: haze asks how milky, luminous transmittance asks how bright, gloss asks how shiny, yellowness index asks how yellow, color difference asks how far from the target, the DSC cooling scan asks how fast the polymer crystallized, and the blocking and friction tests ask what the film surface does. None of them substitutes for another.

Table 5. Which optical or surface test answers which question

ASTM D1925 was withdrawn in 1995 and is not a current yellowness method. No gloss measurement angle is given here because the knowledge base records the gloss standards without their geometry.

There is no single ASTM standard for plastics, only one standard per property, and the full set used for testing plastic additives is indexed on the testing hub. For this property the standard is ASTM D1003-21, for yellowing ASTM E313-20, reapproved in 2025 and valid at a dominant wavelength of 570 to 580 nm, and for color difference ASTM D2244-25, which carries CIELAB and CIEDE2000 among its formulas.

An additive specified to move one of these numbers rarely leaves the others alone, which is the whole problem with matting agents and gloss modifiers for plastics on a clear part: a gloss modifier is specified to scatter reflected light, and the same particles sit in the transmission path. The coupling runs the other way too, since a slip agent bought for a friction target arrives with a bloom that shows up in the haze result a week later.

How to Troubleshoot Haze in a Clear Compound: 7 Steps#

Troubleshooting haze in a clear compound takes 7 steps, and the first decides everything that follows, because surface haze and bulk haze have no fixes in common. The steps run in the order below.

1. Establish whether the haze sits on the surface or in the bulk by comparing a cut face with the moulded or extruded skin, since surface haze points at plate-out, bloom or tool finish and bulk haze at crystallization, particles or gels.
2. Fix the measurement first and record the thickness, the procedure, A or B, and the standard, since the two procedures do not return the same number and a value without a thickness cannot be compared with the specification.
3. Record how old the sample is and, on film, measure again after 7 to 10 days, since slip-agent bloom reaches most of its effect in 24 to 48 hours and settles only after about a week.
4. Check the melt temperature against the clarifier's dissolution temperature, since traditional sorbitol clarifiers need about 220 °C in polypropylene and an undissolved clarifier gives no clarity at any loading.
5. Check every loading against its window, upwards as well as downwards, because more clarifier is not more clarity above 1 wt% DMDBS and an antiblock mineral at the top of a 2,500 to 20,000 ppm range costs far more clarity than one at the bottom.
6. Look for dispersion failures and gels before changing the formulation, since agglomerated pigment, un-melted concentrate and crosslinked polymer all scatter light without any additive being wrong.
7. Confirm the diagnosis with a second test, using the DSC cooling scan for a crystallization cause, the dispersion rating for an agglomeration cause and the yellowness index for a thermal-degradation cause.

One case ends the procedure early: above 30 % haze the material is diffusing, the measurement has stopped being the right one, and no reformulation changes that verdict. Haze is one defect in a longer list, and the same diagnostic order applies to the rest of them under troubleshooting additive-related defects in plastics.

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What Else Does an Optical Specification Need Besides a Haze Number?#

A usable optical specification names more than a haze limit: it names the thickness the limit applies to, the procedure that produced it, the clarity and gloss targets that go with it, and the food-contact status of every additive used to reach it. Haze, clarity and luminous transmittance are three numbers off one specimen, procedure A and procedure B do not agree, and the film surface carries its own tests in blocking and friction. A specification that fixes one of those and leaves the rest open has fixed little: a bare haze figure can be met with a package that fails the reel on the unwind or a migration limit in food contact.

Clarity and gloss targets in a film specification#

A packaging-film specification almost never stops at haze: it pairs a haze limit with a clarity target for see-through quality, a gloss target to ASTM D523 or ISO 2813 for shelf appeal, and a blocking and friction window so the reel still unwinds and runs. Blocking is capped at 200 g to separate 100 cm2 of film under ASTM D3354-21, and the coefficient of friction is read to ASTM D1894-24 or ISO 8295 at a recorded time after production.

The conflict is built into the package: the antiblock and slip additives that make a reel runnable are the same additives that raise its haze, which is why additives for packaging film are agreed as a set rather than one number at a time, with the slip timescale of 24 to 48 hours and 7 to 10 days written into the test plan.

Food-contact limits on the additives that control haze#

Every additive used to hit a haze target in food-contact plastic has to clear two separate systems: in the United States either 21 CFR 178.3295, "Clarifying agents for polymers", which lists 8 substances with their maximum use levels, or a Food Contact Notification that is effective only for the company that filed it and its customers, and in the EU the Union list of Regulation (EU) No 10/2011, where each additive carries an FCM number and, for the newer grades, a specific migration limit of 5 mg/kg. FCM numbers and specific migration limits are explained on EU 10/2011.

Table 6. Food-contact ceilings on 5 additives used to hit a haze target

US figures are maximum use levels under 21 CFR 178.3295 or under the named Food Contact Notification, not recommended dosages, and a notification is effective only for the notifier and its customers. The complete clarifier and nucleator matrix is on the clarifying-agents hub.

Two clarifiers with the same effect on haze can have different legal ceilings, and the ceiling rather than the optics sometimes decides the choice in additives for food packaging. A 250 ppm notification limit and a 0.5 wt% listing are two different design spaces.

Does haze mean the plastic is degraded?#

Usually not: most haze comes from crystallization, dispersed particles or a surface effect rather than from degradation, and the test that answers the degradation question is the yellowness index to ASTM E313-20, not the haze value. The two meet in one place: degraded or crosslinked polymer forms gels, and gels scatter light, so a compound that is both hazy and yellowing is worth checking for thermal damage.

Can you remove haze from a finished plastic part?#

No: the haze of a moulded or extruded part is set in the melt and during cooling, so it is fixed by the formulation, the melt temperature and the tool rather than by anything done to the finished part. One exception exists: surface haze from plate-out disappears when the tool is cleaned, so the parts that follow come out clear even though the hazy ones cannot be rescued. Polishing or coating a finished part is a coatings topic and sits outside the scope of this site.

What is reflection haze and does it apply to plastics?#

Reflection haze is a gloss measurement, not a transmission measurement: it describes the milky halo around a mirror-like reflection on a high-gloss coated or polished surface, and it is read off a gloss instrument rather than a hazemeter. Everything else on this page is transmission haze, measured through the specimen, and reflection haze belongs to coatings and polished metal rather than to a clear compound's additive package.

Why is recycled polypropylene hazier than virgin polypropylene?#

Recyclate is hazier because it carries what virgin resin does not: residual pigment, gels from polymer that has already been through a heat history, and domains of a second polymer whose refractive index does not match the matrix. A clarifier addresses only the crystalline part of that list, so clarity in recyclate is a sorting and filtration question first, and the rest belongs to the wider problem of additives for recycled plastics.

Where can you get haze testing done?#

Haze and luminous transmittance to ASTM D1003 are routine services at independent polymer-testing laboratories and at compounders' own quality laboratories. The request needs three things to be useful: the standard, the procedure, A or B, and the specimen thickness.

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