Re: [PPLetterpress] Re: Interesting thread at Typophile
- On 5/9/04 7:14 PM, "Gerald Lange" <bieler@...> wrote:
> We all know, through simple observation, that there can be substantial gain inI finally got a chance to speak with my technical support at Jet about this.
> letterpress, whether metal or photopolymer. My comment was intended to say
> that there was also some measurable gain to the plate prior to presswork.
> Quite frankly, I'd be more surprised if there wasn't some sort of variable
> than if there was none at all.
I should mention that he answered his phone in a Biergarten in Dusseldorf. I
think he was enjoying Drupa! I asked him about shrinkage or expansion of the
polymer during processing, and responded with several points:
- You can never have a plate match exactly the film, there will always be,
if only at a microscopic level, some variance.
- During the washout process, the plate's surface expands as it absorbs
water. The drying process removes this water and serves to restore the plate
to its original size. A plate that isn't dry enough would be larger than the
original film's artwork and a plate that's too dry would be smaller--it
would have contracted.
- Provided the plate has been dried to the manufacturer's specifications,
the plate should actually contract slightly. Imperceptibly slightly. He gave
the example that a 1% dot on a halftone screen would, on the plate, be more
like a 0.99%. The difference in size is 0.01%.
- Many other variables are at play, including the color of the plate, its
thickness, etc. When he gave numbers, he was speaking about the Jet 94FL and
So that's Jet's take on the issue. I would be interested to hear how this
compares to what other manufacturers say. In the meantime I'll tentatively
plan to sleep more easily!
Fine Printing / Digital Letterpress Supplies
Delavan Center / 501 W. Fayette St. / Studio 222 / Syracuse, NY 13204
315-473-0930 phone / 315-473-0967 fax / www.boxcarpress.com