Ink Purity

[pacificiam]

Hi,

Now a days i am gone crazy with different type of questions.

Today I wanted to know how to check ink purity in offest press room?

We have densitometer, spectrodensitomer, Spectrophotmere.

Please help how this instrument will help me to check the purity of ink?

 

[cementary]

What exactly do you mean by "purity"? Color shade on sheet or ink color in the tin?
If by purity you mean that e.g. cyan is cyan and no magenta particles from next tower comin' maybe a microscope with 40x or mor magnification will help?
And if color shade you mean – you should use spectrophotometer to check delta e deviation from ISO standard either delta e 76 if amd 2007 standard or delta e 2000 if 2013 standard

 

[pacificiam]

Hi,

It mean no any other ink particles from other ink like magenta or yellow.

We want some measurable values.

 

[engin]

One solution may be, if you have a proofer like Orange Proofer and a sensitive weighing balance of 0,000 digits, try to make dry proofs by weighing the transfered amounts of 5-6 proofs on a coated paper that you think standard for you, in my experience CMY between 0,5-0,7 grs/m2 and for black 0,6-0,8 grs/m2 tranfer is ok,then wait for about 3 hours to dry and measure either OD's then make a transfer vs density graph for each batch (but should take some initial batches during start up of this procedure as a reference) and keep them as an entrance QC parameter for the inks of that particular ink supplier or measure the L,a,b values of these 5-6 proofs and try to catch G7 or ISO12647 coordinate values which give the minimum dE,record them, and in any case of pigment reduction, you would see that the required transfer will be high for the same L,a,b coordinate.
I made this in excel, I hope it helps.
Regrads,
Engin

 

[engin]

One solution may be, if you have a proofer like Orange Proofer and a sensitive weighing balance of 0,000 digits, try to make dry proofs by weighing the transfered amounts of 5-6 proofs on a coated paper that you think standard for you, in my experience CMY between 0,5-0,7 grs/m2 and for black 0,6-0,8 grs/m2 tranfer is ok,then wait for about 3 hours to dry and measure either OD's then make a transfer vs density graph for each batch (but should take some initial batches during start up of this procedure as a reference) and keep them as an entrance QC parameter for the inks of that particular ink supplier or measure the L,a,b values of these 5-6 proofs and try to catch G7 or ISO12647 coordinate values which give the minimum dE,record them, and in any case of pigment reduction, you would see that the required transfer will be high for the same L,a,b coordinate.
I made this in excel, I hope it helps.
Regrads,
Engin

Another example, which shows much more better that the corresponding densities against ISO12647-2, dE and tarnsfer amounts.
regards,

engin

 

[pacificiam]

thanks for suggestion.

I think Hue error may help me to find out the contamination of ink.

Any one have any idea.

 

[Alois Senefelder]

Ink Purity.

Present day Lithographic 4 Colour Process Inks are not true ideal inks due to the pigments available


Cyan, Magenta and Cyan are all deficient and unbalanced, this is why we have Colour Correction.


See PDF - Ideal Printing Inks

 

[Cornishpastythighs]

Are you concerned that the press is somehow effecting the purity of the inks? Have your ink supplier pull you some IGT/Little joe ink drawdowns of your current set of inks. Enter these inks as your reference inks into your spectrophotometer. You can now compare on press how the inks are printed using DeltaE as compared to the master values in the spectro.. If you get some high numbers you can then investigate the causes of the contamination. Poor wash up, badly set rollers, rollers out of spec, ink backtrapping.