The published articles are meant to primarily educate the students in printing to supplement their knowledge in the field of Printing. These are not simple Glossary of printing terms, but to the extent possible every term has been explained in brief so that it can be of some use to the students who appear in some sort of examinations and interviews.
I served the Printing Industry for over 40 years
in various capacities, a major part in an Security Printing Organization. In order not to waste the printing and paper related knowledge which I gained over years, I decided to keep them in public domain for the reason stated in prepara. Most of the illustrations - over 90% - have been generated by me to explain the terms suitably.
While I am not sure to what extent the published content will help, if the content is going to be of use to some one in some manner, I will be greatly satisfied.
Your views may be sent to me (
nrj_1945@yahoo.com) for my record and correction wherever needed.

TOTAL NO OF PRINTING TERMS

POSTED TILL NOVEMBER, 2012

- Over 400 terms-

Click on this line to read from 'A'

Saturday, July 6, 2013

How to balance Taggant with Ink - 3

How to balance  Taggant  
(Marker  Ink) with  Ink  
-  Simple Laboratory  Test-
- III -
(Written  by   :   N. R. Jayaraman )

PARTICLE  SIZE  OF  THE TAGGANT
The   particle   size    of   the   pigment    or   the   taggant  is  very    important   factor  in determining   the    effective    working   and balancing   of   Ink- Taggant.   The   particle   size   is  always   expressed   in   terms   of  microns.

Like   the  pigments  in   inks,    the    particle   size    of    Taggants  too affect  the print  quality  unless  it  blends    well   with   the particles of  the  colored   pigments  present  in  the  ink.   So both  the  pigments  and  the  particle  size  of   the   taggant   powder   plays  an important  role   wherever  they  are  put  to  use  together. 

The   particle  size  is measured  by  simple  manual  rubbing on particle size measurement s lab    which   needs   experience   to   handle  or by automatic equipments  such  as dynamic  light  scattering (DLS) devices.  Most  of  the  ink  pigments  fall  into  the range  of  50-200 nm (microns).
 
Manual   Particle    size   rub  Test  slab  with   scale

When  the  particle  sizes  of  the  pigments  are  in  the  following  range one  can  expect  trouble   free  printing  and free  flow of   ink  on rollers and ink  duct.
  • General Wet offset inks < 5-6 microns
  • General Dry offset inks < 5-6 microns
  • Intaglio inks around 20-25 microns
  • Flexographic inks <5-8 micron (slightly  courser  is  acceptable –e.g. 15 micron  can  be  run  with  a  high  release  anilox  but  not totally problem free)
  • Writing  or   liquid   inks  which  is   powder based.  Since   they   are  Solubilised  dye–the   particle   size    should   be   theoretically  zero micron.
In  view  of   the  above,  if  the   particle  size  of   the  Taggants  are  kept  below 1- 2 micron, it  will  get  blend   well   with   ink  to   produce  excellent  result.  

In  my   personal   opinion   the   smaller   the   size   of   the   particle, the  better   will   be   the   tendency   to   blend   well   with  the  liquid ink ,  particles   being    lighter   in   weight.   To  determine   the   ideal  particle    required   for   working    the    following   trials   could be   carried    out. 

Step   one 
  • Get  two   or   three   grades   of   Taggants  in  particle   sizes    say  mean  5 micron,  mean  3-4 micron  and  mean  2-3 micron  and  test   the  result  in   the same way  to   see  which  works   better.
  • Once  you  short  list  the  grade  then  the  set  of  samples can be taken  up   for  actual   machine   trial    as    there    will    be   10- 15 %  variation   in   performance   between   machine   and lab   trials   which   are  manually   operated . Such   minor    variations   can   be   easily   adjusted   on   machines.
Machine   trial   
Step  Two

The   machine   trials  could   be   taken   at  the   beginning   of   the   day when  the rollers  would  have   remained   fresh   or   after  the   production  is  completed.   But   before    taking   machine    trials    the   inking   roller   and   ink   duct    must  be   well   cleaned  to   observe   sedimentation   or  clogging   of   the   Taggant   powder.

Since  no  machine  make  ready  will  be  required  and  the  ink  will have   to   be   simply   poured   from   the   container no   special  care   may   be   necessary.   

Maximum   of   three   samples   of    liquid  ink  in  three    different   colors –  Violet,  Red  and  Black  could  be   used   avoid  mix   up  of  the   samples.  

The above exercise will help in assessing:
  • Whether  ink   agitator   will   be   required    to   ensure   perfect   blending   of   Taggant   with   the   ink  or   not. 
  • Whether   the   final   consignment  could   be  obtained   in  small  size   bottles   of   100   or  200  ml   which   can   be  shaken   well   and   poured   manually   in   the   ink   duct   or   directly   on   the  roller. 
  • Whether  the  Taggant   has   tendency   to   sediment  if   the  ink   duct    solution   is   not  constantly   stirred .
  • Whether   the   Taggant   blend  well   with   the   liquid   ink   and  flow   freely   from   the  ink   duct    due   to   the   continuous  rotating  action   of   the  ink   roller   which  continuously  rotates    in   the   duct    once    the   machine   starts   working.
  • The  strength  of   the   solution  (percentage    of   the   Taggant) which  needs  to  be   supplied.
  • Whether  adding   10- 20 %  thinner   at   frequent    intervals  in   the ink   duct   continue  to   maintain   desired   result   or   whether   fresh    solution   is   only  needed   to   be  poured    in   the   ink   duct.     
  • Since    there    will   be   no   vibrating   rollers    in   the   inking   unit , while   taking   machine   trials  the   three    grades   of   solution   could   be   poured  in   three   parts  with   a   gap   of 1 inch  minimum  and  prints   taken   so   that   in  one  run  the  performance   of   the   three  samples  can be  tested    without  wasting   much time  .
 
 -----------CONCLUDED----------

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