[\/et_pb_text][et_pb_text _builder_version=”4.24.3″ header_3_font=”|700|||||||” background_size=”initial” background_position=”top_left” background_repeat=”repeat” global_colors_info=”{}”]<\/p>\n
![\"Spectrum](\"https:\/\/hunterlab.de\/wp-content\/uploads\/2024\/04\/Spektrum-UV.jpg\")
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The human eye<\/a> sees the range between 400 nm and 700 nm. [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_text _builder_version=”4.24.3″ text_font_size=”18px” header_3_font=”||||||||” background_size=”initial” background_position=”top_left” background_repeat=”repeat” global_colors_info=”{}”]<\/p>\n To counteract this, optical brighteners or so-called whiteners<\/strong> are often used. These chemical substances are used to make white products such as detergents, toothpaste, textiles or paper<\/strong> appear whiter by enhancing the reflection<\/a> in the range between 400 and 550 nm through their fluorescence<\/a>. This effect is also used for signal colors<\/strong> to make the colors shine more brightly. <\/p>\n For color measurement on fluorescent samples<\/strong>, the exciting light<\/a> must therefore have UV components. If you want to determine the fluorescence<\/a> component, you need two measurements: one measurement with UV component and one without UV component of the measuring flash<\/strong>. <\/p>\n The HunterLab Agera<\/a> (see above) can switch the UV component of the light<\/a> source on or off and calibrate it. If reflectance values of over 100 % are measured when the UV range is switched on, the sample is clearly fluorescent. If this result is compared with a measurement without the UV component of the light<\/a> source, the fluorescence<\/a> component can be determined.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.24.3″ background_color=”#dde699″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” custom_padding=”|10px||10px|false|true” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_text _builder_version=”4.24.3″ text_font_size=”18px” header_3_font=”||||||||” background_size=”initial” background_position=”top_left” background_repeat=”repeat” custom_margin=”||80px||false|false” custom_margin_tablet=”||20px||false|false” custom_margin_phone=”||20px||false|false” custom_margin_last_edited=”on|tablet” locked=”off” global_colors_info=”{}”] Read in our current HunterLab NEWS magazine how three different liquid adhesive samples were analyzed for their fluorescence<\/a> content in a laboratory test. The magazine also contains other exciting articles on the subject of color measurement of liquids and solids. <\/p>\n Fill in the two fields below and we will send you the magazine as a PDF!<\/em><\/span>[\/et_pb_text][df_gravity_form gravity_forms=”18″ use_ajax=”on” input_padding=”15px||15px||true|false” button_align=”center” button_background_bgcolor=”#2A4175″ button_padding=”15px|20px|15px|20px|true|true” _builder_version=”4.27.4″ _module_preset=”default” button_font=”|700|||||||” button_text_color=”#ffffff” button_font_size=”16px” hover_enabled=”0″ custom_css_main_element=”.gform_wrapper.gravity-theme .gfield input.large, .gform_wrapper.gravity-theme .gfield select.large {|| width: 100%;|| padding-top: 15px;|| padding-bottom: 15px;|| border-radius: 5px;||}” border_radii_input=”on|5px|5px|5px|5px” border_radii_textarea=”on|5px|5px|5px|5px” border_radii_button=”on|5px|5px|5px|5px” border_color_all_button=”#2A4175″ locked=”off” global_colors_info=”{}” button_background_bgcolor__hover_enabled=”on|hover” button_background_bgcolor__hover=”#FFFFFF” button_text_color__hover_enabled=”on|hover” button_text_color__hover=”#2A4175″ sticky_enabled=”0″][\/df_gravity_form][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":" An ideal white surface has a reflection<\/a> spectrum<\/a> that is close to 100% in all visible wavelength<\/a> ranges. That doesn’t happen in our everyday lives. Particularly in the wavelength<\/a> range between 400 nm and 550 nm (blue-green), many everyday materials such as paper, textile fibers and plastics, which should actually be white, still absorb a considerable amount of light<\/a> due to their natural components or production, despite strong bleaching. This leads to a more or less pronounced yellow or brown tint in these materials. <\/p>\n","protected":false},"author":2,"featured_media":287344,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[806],"tags":[1250,1249],"class_list":["post-346097","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-colorimetry","tag-laboratory-device","tag-uv-quantification"],"_links":{"self":[{"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/posts\/346097","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/comments?post=346097"}],"version-history":[{"count":0,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/posts\/346097\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/media\/287344"}],"wp:attachment":[{"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/media?parent=346097"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/categories?post=346097"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hunterlab.eu\/en\/wp-json\/wp\/v2\/tags?post=346097"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
Ultraviolet rays, on the other hand, are invisible and lie between 100 nm and 400 nm.<\/em><\/p>\nWhat happens during fluorescence?<\/h4>\n
![\"HunterLab](\"https:\/\/hunterlab.de\/wp-content\/uploads\/2020\/12\/HunterLab-Agera-Klebstoff-messen-1920w-200x300.png\")
A fluorescent substance has the property that it absorbs light<\/a> from the invisible ultraviolet range<\/strong> of sunlight or from fluorescent tubes, absorbs part of the energy and re-emits the greater part as light<\/a> in the visible range. Emission usually takes place in the blue or green visible light<\/a> range. This means that a reflection<\/a> of over 100 %<\/strong> is measured in this area, as the transformed component is added to the reflection<\/a> of the incident light<\/a>. This covers yellow tones or “gray haze<\/a>”<\/strong> of the object<\/a> in particular. The wavelength<\/a> of the emitted light<\/a> in the fluorescence<\/a> effect is usually between 400 and 550 nm, i.e. in the blue and green range of the visible spectrum<\/a>. However, there are also substances that fluoresce in the red range. <\/p>\n![\"HunterLab](\"https:\/\/hunterlab.de\/wp-content\/uploads\/2024\/04\/HunterLab-NEWS-01-DE-Vorschau-1920w-292x300.png\")
<\/p>\nPractical example: Measurement method – Measuring white adhesive with the HunterLab Agera<\/h3>\n