Why buy an IQ, not a glossmeter?



A high quality finish is important in a huge number of industries. “High gloss, deep finish, smooth and homogenous.”
Orange peel and haze have a huge impact on finish quality.
Potential causes – coating formulation, substrate, application technique & conditions, drying/curing.
A glossmeter cannot measure these effects that reduce visual quality.

Rhopoint IQ- the ultimate glossmeter upgrade.



Who needs these extra measurements?

Rhopoint IQ
Rhopoint IQ

Proven applications in:

  • Paints & coatings
  • Powder coatings
  • Additives
  • Inks
  • Plastics
  • Wood coatings
  • Yacht manufacture
  • Automotive
  • Aerospace
  • Polished stone and metals
  • Glass manufacture
  • Consumer electronics
  • Anodised metals

Gloss measurement with a diode array

Gloss angle

The Rhopoint IQ has standard glossmeter optics @ 60° & 85° and a high definition 512 element LDA @ 20°+/- 7.25°.

Which angle is best for my application?

best angle for my application

Surfaces with gloss < 10GU @ 60º should be measured with the 85º geometry.
Samples where gloss is > 70GU @ 60º measure with the 20º angle.

Reflectance Haze

Haze is light that has been reflected by small surface structures adjacent to the main specular component.


Low Reflance Haze
Example: Low reflectance haze
High Reflectance Haze
Example: High reflectance haze

A surface without haze shows deep reflection whereas a surface with haze shows loss of reflective contrast.

haze on curved surface

A slightly curved surface with low haze shows minimal halos whereas a hazy surface shows multiple halos.

Causes of Haze

Coating & Raw Materials

  • Dispersion
  • Pigment properties
  • Particle size
  • Binder compatibility
  • Influence and migration of additives
  • Resin types and quality



  • Drying conditions
  • Cure temperature

Post Coating

  • Polishing marks
  • Cleanliness
  • Ageing and oxidisation


Haze is often visible as a milky finish on high gloss surfaces


Orange Peel

Orange peel is a surface texture which resembles the skin of an orange

Causes of Orange Peel


  • Improper gun adjustment and technique
  • Over-spray/dry spray
  • Brush marks
  • Improper flash or recoat time
  • Substrate roughness/waviness
  • Sag on vertical surfaces

  • Incorrect coating, primer or clear coat film thickness
  • Poor particle size distribution
  • Incorrect viscosity leading to poor flow
  • Flake alignment
  • Resin types and quality
  • Surface energy incompatibility
  • Incorrect curing/environmental conditions

Distinctness of Image- DOI

Distinctness of image is the aspect of gloss characterized by the sharpness of images of objects produced by reflection at a surface.

Low DOI is caused by large surface structures distorting the reflected light. The surface is visible: orange peel.

Distinctness of image

The Rhopoint IQ measures all aspects of reflective appearance

Three high gloss coated panels measure identically using a standard glossmeter, but orange peel dramatically reduces the perceived quality of the surfaces with texture.

Gloss readings @ 20º approximately 85GU
Gloss readings @ 60º approximately 93GU

Only by using additional parameters of DOI/RIQ can the visual quality be measured.

Goniophotometric curves

Goniophotometric curves clearly show the visual differences between the a smooth surface, a medium texture surfance and a high texture surface.

RIQ- Reflected Image Quality

RIQ is a more sensitive, updated version of DOI. A new high sensitivity/high resolution sensor allows improved measurement.

ACT panels


DOI is not sensitive to low amounts of orange peel on highest quality surfaces.

RIQ has more proportionate response to orange peel on a wider range of surface finishes.

RIQ works well in differentiating low gloss surfaces with different specular/diffuse components.

DOI Measurement

Rhopoint IQ– DOI

Quality differences between economy and premium are seen, poor orange peel on economy filler cap is shown, however horizontal and vertical surfaces are not differentiated.

DOI measurement wavescan

Wavescan– DOI

The DOI values do not reflect differences between horizontally and vertically sprayed panels; premium and economy models are not differentiated.

RIQ measurements

RIQ Measurements

RIQ measurement is sensitive enough to appearance differences due to-

  • Substrate alignment (horizontal/vertical)
  • Coating formulation
  • Substrate
  • Application technique

Rhopoint IQ

Sample Flatness Compensation

glossmeter iq readings

20° gloss & haze meters have fixed geometry. They require very flat surfaces to measure accurately.

The Rhopoint IQ uses a 512 element sensor that measures 20 +/- 7.25°. It mathematically determines the gloss angle.

Gloss meter incorrect reading

With a standard gloss meter non-flat surfaces cause light to reflect on an incorrect part of the sensor and give inaccurate gloss results. With the Rhopoint IQ light is reflected on different areas of the diode array, and the instrument automatically compensates for the surface irregularities.

glossmeter graphical readout

On the left : Two similar appearance surfaces, one is curved- the reflected light falls away from the centre of the array.

The reading on the right showing the IQ automatically compensating for non-flatness.

Law of Reflection: The direction of incoming light and the direction of outgoing light reflected make the same angle with respect to the surface

Ready to find out more?

Read more about the Rhopoint IQ features