[argyllcms] Re: Profiling flexo presses

  • From: Roberto Michelena <colorsync@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 22 Aug 2005 10:25:03 -0500

> How do you propose to use a bump curve that linearize a 2% dot on press?

ok flexo people usually refer to this as bump curve but is really a
cutback curve.
You need a rip capable of large supercell screening together with
linearization (linearization integrated in screening).
You can't use too high a resolution, because you need the minimum dot
to be reproducible on press. So better to use 1200 or 1270dpi, that
way your minimum dot will be 20 or 21 microns.
Then you just create patches from 0 to 10% in 50 steps (so 0.2% each
step), better in vector (precision is higher), output them linear,
print, measure, and build your first curve.
With that curve active in the rip, you print patches from 1% to 15% in
1% steps and measure again. you correct the first curve with the
second set of measurements. Harlequin allows this, other rips too.
Barco Intellicurve does too.

How much highlight you'll be able to get depends on using a low
resolution, on your rip's screening and curve capabilities, and on
your platemaking and press capabilities. If you don't use a low
resolution, you'll need special screening such as Samba or Sublima or
something like that to limit the minimum imaged dot.
I'm not sure how easy is it to print 21 microns on flexo, maybe 30
microns would be more like it, then you'd need to force resolution
down to 900dpi which will give you grainy images. That's why special
screenings are so popular in flexo, they limit the minimum dot while
keeping a high resolution.

we are quite out of topic here, aren't we? I'm somewhat new to the
world of flexo, haven't suscribed to a flexo forum yet except FlexPack
in Printplanet that has so little activity...

-- Roberto Michelena
   Infinitek
   Lima, Peru

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