Fulcrum Insights | Clarity, Haze & Transmittance
High Transmittance but Poor Clarity? How to Evaluate Haze, Light Transmittance and Clarity
A transparent material can transmit plenty of light and still look hazy, blur outlines or reduce visual contrast. Films, plastic sheets, packaging, optical films and display materials should therefore be assessed by more than transmittance alone. This guide explains the differences between transmittance, haze and clarity, and when clarity testing may be needed.
In brief: transparency does not always mean visual clarity. Transmittance tells you how much light passes through a material. Haze indicates how much transmitted light is scattered. Clarity describes whether images and outlines remain sharp after passing through the material. If a product must preserve readable text, visible patterns or display details, consider haze, scattering and clarity together.
BASIC CONCEPTS
What do transmittance, haze and clarity measure?
Transmittance — how much light passes through
Transmittance describes the proportion of light that passes through glass, film, plastic sheet or transparent packaging. A high value means more light gets through; it does not guarantee a sharp image.
Haze — cloudiness caused by scattered light
Haze relates to the proportion of scattered light. Rough surfaces, uneven internal structures, dispersed fillers, coatings or processing can redirect light and make a material look whitish, cloudy or misty.
Clarity — whether an image remains sharp
Clarity concerns the sharpness of images, text and object outlines seen through a transparent material. Some materials have respectable transmittance and moderate haze yet still look unclear because light spreads and fine-detail contrast falls.
WHY IT HAPPENS
Why can a high-transmittance material still look unclear?
Appearance also depends on scattering direction, surface condition, internal structure, thickness, coatings, texture and processing. When light spreads as it passes through a material, outlines may lose sharpness even when enough light is transmitted. Common examples include packaging that looks less transparent than expected, a screen that appears hazy through a protective film, an optical film that reduces image detail, and plastic sheet that meets its transmittance target but looks unclear to customers. A single transmittance number cannot explain these issues.
For background, see the differences among haze, transmittance and transmission, and the comparison of ASTM D1003, ISO 13468 and ISO 14782.
COMPARISON
Which measurement answers your question?
| Measurement | Question | Use |
|---|---|---|
| Transmittance | How much light passes through? | Assess light transmission and total luminous transmittance. |
| Haze | How much transmitted light is scattered? | Investigate cloudy, whitish or misty appearance. |
| Clarity | Do images and outlines remain clear? | Analyze text, graphics or display details that look soft despite adequate transmittance. |
| Overall appearance | Does the material meet its intended transparency requirements? | Assess haze, transmittance and clarity according to the application. |
Explore haze and transmittance instruments.
APPLICATIONS
Where might clarity testing be useful?
Transparent packaging
Food, cosmetic, electronics and display packaging may need to show the product clearly, so appearance and clarity can matter alongside transmittance and haze.
Protective and optical films
These materials can affect transmission, scattering and image details. Decide whether clarity evaluation is needed based on the end use.
Transparent plastic sheets
PC, PET, PMMA and acrylic used for windows, panels, covers or displays may need good visual definition, not just high transmittance.
Displays and high-transparency materials
If a material affects display content, image details or visual contrast, clarity may be relevant to quality control and R&D.
SELECTION GUIDE
Choose a meter based on the application
YH40
Portable, on-site checks. Consider it for incoming inspection, patrol checks or quick process checks focused on haze and transmittance.
YH1100 / YH1200
Vertical standard measurement. Compare these models for controlled haze and transmittance QC, taking ASTM/ISO requirements, customer specifications and samples into account.
YH1210
Horizontal haze and transmittance measurement. Consider it for flat films, sheets, glass and transparent packaging when transmitted color and clarity are not required.
YH1600 / YH1610
Add transmitted color and color difference. Consider these when CIE Lab, color difference or transmitted-color data are needed in addition to haze and transmittance.
YH1810
Adds clarity measurement. Consider it when a sample also requires clarity testing. This is an important application difference between the YH1810 and YH1610.
When should you evaluate clarity?
Haze and transmittance are often enough for basic transparent-material QC. If the product is used with images, text, graphics, display content or visible outlines, those two values may not fully describe its appearance. High-clarity packaging, optical films, display materials, protective films, transparent panels and viewing windows may need clarity testing to check outlines, details and contrast through the material.
Choose a direction based on the need
- Quick check for cloudiness: haze and transmittance measurement for incoming inspection, patrol checks and batch comparison.
- Color data as well: haze, transmittance and transmitted-color measurement for QC or R&D.
- Image or text sharpness: clarity and transparent-material appearance analysis for high-transparency packaging, optical films, display materials and R&D.
If the requirement extends from haze and transmittance to image sharpness, consider the YH1810. If haze, transmittance and transmitted-color data are sufficient, consider the YH1610.
Before requesting a quote
Prepare the sample's intended use (packaging, protective film, display material, optical film, viewing window, plastic sheet or other transparent material); the issue to solve (low transmission, haze, blurred outlines or customer-specified values); material, thickness, dimensions, coating, surface texture, matte finish, color and flexibility; and any required ASTM, ISO or internal standard, report fields, acceptance limits and current QC process.
FAQ
Frequently asked questions
1. Why can a material look unclear even with high transmittance?
Transmittance indicates how much light passes through, not whether it keeps its original direction. Scattering can make the material look cloudy, blur outlines and reduce detail contrast.
2. Does low haze guarantee good clarity?
No. Haze and clarity are related but are not the same measurement. A material with low haze can still soften an image or reduce fine-detail contrast.
3. When should clarity be evaluated?
Consider it when the material is used with images, text, displays, product presentation or visible outlines, such as optical films, transparent packaging, display materials and high-transparency sheets.
4. Must I specify clarity testing right away?
Not necessarily. First describe the sample, its use and the issue—for example, transmittance meets the target but the material still looks unclear. Then determine whether clarity measurement is needed.
5. What sample information should I prepare?
Provide material, thickness, dimensions, use, coating or matte treatment, the appearance issue, and any ASTM/ISO or customer acceptance requirements.