Visual and Instrumental Evaluation of Mottling and Striping

Visual and Instrumental Evaluation of Mottling and Striping Friedhelm Fensterseifer and Severin Wimmer BYK-Gardner User Meeting 2013 - Innsbruck, Austria

Mottling / cloudiness of metallic coatings Irregular areas of lightness variation undesirable defect at effect coatings especially noticeable on large body panels most obvious on light metallic finishes Page 2, BYK-Gardner GmbH, cloud-runner

Mottling / cloudiness of metallic coatings Flake orientation Parallel & uniformly distributed Disorientation or varying hiding Page 3, BYK-Gardner GmbH, cloud-runner

Perception of Mottling Depending on illumination, viewing angle, distance and size Page 4, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Which pattern size is perceived as mottle? Experts and non-experts mainly recognize mottle sizes between 50 to 100 mm. Extremes ranged from 25 to 200mm. Therefore, for visual inspection and measurement a min. sample area of about 300 x 500 mm is recommended. 50mm 100mm 200mm 25mm Page 5, BYK-Gardner GmbH, cloud-runner

How to measure Mottling Scanning the mottle pattern scanning 10 100 cm Page 6, BYK-Gardner GmbH, cloud-runner

Measurement Optical principle Illumination 15 to perpendicular Detection 15 Specular reflection Detection 45 Detection 60 Spot size approx. 4x4 mm Page 7, BYK-Gardner GmbH, cloud-runner

Measurement Minimize the influence of tilting Illumination 15 to perpendicular Detection +15 Specular reflection Detection -15 Sample surface Page 8, BYK-Gardner GmbH, cloud-runner

Measurement Minimize the influence of tilting Illumination 15 to perpendicular Detection +15 Specular reflection Detection -15 Sample surface Object curvature radius > 500 mm Page 9, BYK-Gardner GmbH, cloud-runner

Measurement Influence of tilting - Character Lines 0.7 0.6 0.5-15 + 15 ± 15-15G 15G ±15 0.4 0.2 0.1 45 60 45G 60G 0 Page 10, BYK-Gardner GmbH, cloud-runner

Measurement Cloud ranges The signal is separated by mathematical filters: Visibility Mottle Size min. scanlength Md 6-13 mm Me 11-24 mm Mf 19-42 mm 110 mm Mg 33-72 mm 210 mm Mh 57-126 mm 370 mm Mi 100-200 mm 650 mm Page 11, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Which pattern size is perceived as mottle? 10 9 8 7 6 5 4 3 2 1 Small Mottles Large Mottles 0 Md 6-13mm Me 11-24mm Mf 19-42mm Mg 33-72mm Mh 57-126mm Page 12, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Texture & Mottling Small Mottles Large Mottles 10.0 9.0 Probe_1 8.0 7.0 Probe_3 6.0 Probe_5 5.0 4.0 3.0 2.0 1.0 0.0 6-13mm M15d 11-24mm M15e 19-42mm M15f 33-72mm M15g 57-126mm M15h M15d M15e M15f M15g M15h Small Mottles = (Md+ 0.5Me) / 1.5 Page 13, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Texture & Mottling Mottling is dominated by the max value of the large mottles 10.0 9.0 8.0 7.0 6.0 5.0 4.0 Large Mottle: avg. max. Sample A 3.8 4.6 Sample B 3.7 3.8 3.0 2.0 1.0 LM = (0.5Mf+ max (Mg,Mh)) /1.5 0.0 6-13mm M15d 11-24mm M15e 19-42mm M15f 33-72mm M15g 57-126mm M15h SM = (Md+ 0.5Me) / 1.5 Page 14, BYK-Gardner GmbH, cloud-runner

Texture & Mottling Small mottles overlay large mottles and reduce their visibility Page 15, BYK-Gardner GmbH, cloud-runner

Texture & Mottling Small mottles overlay large mottles and reduce their visibility Page 16, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Texture & Mottling - 2 dimensional graph Large Mottles (LM) 15 12 11 10 9 8 7 6 5 4 3 kaum sichtbare Wolkigkeit Visual Ranking: sichtbare Wolkigkeit clearly noticeable deutlich sichtbare Wolkigkeit visible hardly to recognize 2 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Small Mottles (SM) 15 Page 17, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Texture & Mottling - 2 dimensional graph Large Mottles (LM) 15 12 11 10 9 8 7 6 5 4 3 kaum sichtbare Wolkigkeit Visual Ranking: sichtbare Wolkigkeit clearly noticeable deutlich sichtbare Wolkigkeit visible hardly to recognize 2 1 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 Small Mottles (SM) 15 Page 18, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Small & Large Mottles weighted for visual correction Small mottles in the range of mm to cm overlay Large Mottling and reduce their visibility. Large Mottling needs to be corrected by influence of SM: M = LM * ( 1 -f * T ) f (15 ) = 0.05 f (45 ) = 0.04 f (60 ) = 0.03 Texture: Small Mottling with shifted zero (pivotal point): Texture = SM -6 Page 19, BYK-Gardner GmbH, cloud-runner

Evaluation of Mottling Texture & Mottling 12 11 10 Visual ranking: 9 M Mottling 15 8 7 6 5 4 clearly noticeable visible hardly to recognize 3 2 1 0-6 -5-4 -3-2 -1 0 1 2 3 4 5 6 7 T - Texture 15 Page 20, BYK-Gardner GmbH, cloud-runner

Mottle-Chart Example: Medium class models 12 11 Karossen Mw M Mottling - 15 10 9 8 7 6 5 4 Body panels Wolken deutlich sichtbar 3 2 1 0-6 -5-4 -3-2 -1 0 1 2 3 4 5 6 Mc T - Mottling - Texture Coverage 15 Page 21, BYK-Gardner GmbH, cloud-runner

Texture - dependend on color / pigment type 10 9 15 White Pearl 10 9 15 Silver 10 9 60 White Pearl 10 9 60 Silver 8 8 8 8 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 3 3 3 3 2 2 2 2 1 1 1 1 0 Md Me Mf Mg Mh Mi 0 Md Me Mf Mg Mh Mi 0 Md Me Mf Mg Mh Mi 0 Md Me 0f Mg Mh Mi 20 18 15 Black Pearl 10 9 60 Black Pearl 16 8 14 12 10 8 7 6 5 4 no mottling visible under 60 angle 6 3 4 2 2 1 0 Md Me Mf Mg Mh Mi 0 Md Me Mf Mg M6 Mi 10 White Pearl Black Pearl Silver 10 White Pearl Black Pearl Silver 9 9 8 8 7 7 Mottling 15 6 5 4 3 2 1 Mottling 60 6 5 4 3 2 1 0 0-6 -4-2 0 2 4 6 8 10 12 14 Texture15-6 -4-2 0 2 4 6 8 10 12 14 Texture 60 Page 22, BYK-Gardner GmbH, cloud-runner

Mottling versus Orange Peel Observing direction Mottling Orange Peel 45 15 specular reflection 60 60 off-specular in specular direction

Mottling versus Orange Peel Pattern size Mottling large irregular patches 25 ~ 200 mm Orange Peel small, wavy pattern 0.1 ~ 30 mm 10 x 10 cm Page 24, BYK-Gardner GmbH, cloud-runner

Mottling versus Orange Peel Pattern size Mottling large irregular patches 25 ~ 200 mm Orange Peel small, wavy pattern 0.1 ~ 30 mm 10 x 10 cm Sample size 30 x 50 cm Viewing distance > 3 m 10 x 30 cm < 3 m Page 25, BYK-Gardner GmbH, cloud-runner

Irregular mottle distribution Measurement hints Recommended sample area ~ 30 x 50 cm 10 scans in 1-2 cm distance min. scanlength: 37 cm for Mh 21 cm for Mg & M Page 26, BYK-Gardner GmbH, cloud-runner

Mottling versus Orange Peel Contrast Mottling Scattering from pigments very low contrast Orange Peel Surface reflection high contrast Page 27, BYK-Gardner GmbH, cloud-runner

Visual evaluation What influences recognition of mottling? Reflection of surrounding objects overlays mottling Object curvature disturbs visibility Blinded by illumination highlights Ratio of direct to diffus illumination Page 28, BYK-Gardner GmbH, cloud-runner

Visual evaluation On panels viewing angle and light intensity 15 60 300cm Page 29, BYK-Gardner GmbH, cloud-runner

BMW Group Labortechnik 06.10.2010 T. Schäckeler Page 32 Customer relevant evaluation of cloudiness. Correlation study - panels.

Visual evaluation On cars Dimmable light source? Changing lightning conditions Reflections (bags; poster; persons; etc.) Changing lightning conditions e.g different angle Page 33, BYK-Gardner GmbH, cloud-runner

BMW Group Labortechnik 06.10.2010 T. Schäckeler Page 34 Customer relevant evaluation of cloudiness. Field study Customer relevance. Standardised conditions for the visual evaluation.

Striping Measurement direction Paint application Scan direction Page 35, BYK-Gardner GmbH, cloud-runner

Striping on cars Horizontal vs. vertical stripes Page 36, BYK-Gardner GmbH, cloud-runner

Striping on cars Character lines Page 37, BYK-Gardner GmbH, cloud-runner

Striping on cars Striping and measurement Light silver Page 38, BYK-Gardner GmbH, cloud-runner

Striping Calculation of Mercedes & extended formula Tolerances of Mercedes Striping 15 : 15 Mh-Mg < 0.5 15M < 4.5 Mottling 15 : Extended striping formula (Mi included) Striping 15 / 45 / 60 : Page 39, BYK-Gardner GmbH, cloud-runner

Striping Mottle index and striping index analysis Tolerances of Mercedes Striping 15 : 15 Mh-Mg < 0.5 15M < 4.5 Mottling 15 : 8 M 15 7 6 5 4 3 2 1 High Mottling Mottling and Striping: OK High Mottling and Striping Obvious Striping 0-2 -1.5-1 -0.5 0 0.5 1 1.5 2 Striping 15 Mh Mg Page 40, BYK-Gardner GmbH, cloud-runner

Striping analysis Mercedes measurement data on hoods 7.00 6.00 5.00 Hoods Scanning direction: In application direction Across application direction 4.00 3.00 2.00 1.00 good good across beginning striping beginning striping across striping striping across cloudy cloudy across 0.00 M15d 6-13mm M15e 11-24mm M15f 19-42mm M15g 33-72mm M15h 57-126mm M15i 100-200mm Page 41, BYK-Gardner GmbH, cloud-runner

Striping analysis Mercedes measurement data on hoods 6.00 5.00 4.00 Mottling 15 3.00 2.00 good beginning striping striping cloudy Tolerance 1.00 0.00-2.00-1.50-1.00-0.50 0.00 0.50 1.00 striping 15 Mh-Mg Page 42, BYK-Gardner GmbH, cloud-runner

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