How to to estimate the lightfastness of offset ink

[conghieu_h2c]

hi everybody. I want to estimate the lightfastness of offset ink (sheet feed). but i don't know how method to estimate the lightfastness of offset ink. please help me.Thanks

[gordo]

Although more directed toward ink jet printers, you may find the info on this site to be a start:

Wilhelm Imaging Research

Also this PDF about Commercial inks: http://www.hubergroup.info/lang/en/tipdf/19102E.PDF

best, gordon p

[Cold]

Hi conghieu_h2c

Your fade resistance will vary greatly between the pigments typically used in sheet-fed inks. Most flourescents show a color shift after very little light exposure vs. Neutral black will remain fast for years. I will include the light fastness for 4cp below, if you require different colors from these, please indicate and I will do my best to help.

Untoned Black(pigment black 7)
- tint - Outdoor exposure(Florida), Max tolerance: greater than 12 mos..
- Fadeometer, greater than 240 hrs.

Process Cyan(pigment blue 15:3)
- tint - Outdoor exposure(Florida), Max tolerance: 24 mos. with fading.
- Fadeometer, Max tolerance: 120-160 hours shows fading and loss of gloss

Process Magenta(pigment red 57)
- tint - Outdoor exposure(Florida), Max tolerance: less than 1 month fading & loss of gloss
- Fadeometer, Max Tolerance: 5-25 hours shows fading and loss of gloss

Process Yellow(pigment yellow 12)
- tint - Outdoor exposure(Florida), Max Tolerance: less than 1 month fading
- Fadeometer, Max Tolerance: 2-30 hrs shows fading and loss of gloss

Also, please keep in mind that there are usually solutions availible to gain light fastness by changing from the normal pigment used. For example, the violet used in the pantone book is methyl violet which has poor light fastness, but by substituting carbazole violet you gain a very permanent color. It is not always this easy. For example, rhodamine red has poor light fastness, but the light fast substitute for this pigment is much dirtier in color.

Cold

[turbotom1052]

if i remember correctly you can send GATF a drawdown of the ink you want tested and they will do a controlled test and provide you with results that are quantifiable and repeatable. not sure of the cost but ill bet its cheaper if your a member of the foundation