Re: Kodak "Thermal Direct" Plate
Hi Gaz,
The Thermal Direct plate was designed as a develop-on-press plate, and as such, Kodak does not offer or recommend use of a standalone processing option.
As you are probably aware, develop-on-press technology is not a new idea. Over the years, several manufacturers, including Kodak, attempted to bring DOP plates to market. Though workable, the technology previously did not enjoy success, largely because the removed coating was found to contaminate the press: compromising ink colors, altering the wetting characteristics of fountain solutions, and changing ink flow and tack.
Throughout the development of the Thermal Direct plate, Kodak research scientists paid particular attention to these problems of DOP technology. Extensive research indicated that the cause of press contamination was twofold: 1) the high coating weights needed to provide acceptable run lengths could not be adequately dispersed by inks and founts and carried away by the press sheet; and 2) the coloring agents used to make the plate image highly visible contaminated inks and fountain solutions.
To address the first issue, Kodak’s synthetic chemists developed a unique coating resin with a proprietary molecular structure that enables the coating resin to be applied in a layer that is ultra thin, yet durable enough for run lengths of 100,000 impressions or more. Extensive testing has shown that dispersion of this very small amount of coating has no effect on either the wetting characteristics of the fountain solution or the viscosity and laydown properties of the ink.
While researching the second issue, Kodak chemists determined that the coloring agents traditionally added to coating resins to render a plate image highly visible were, when used in a develop-on-press environment, a major source of ink color contamination. Thus, the colorants added to the custom resin for Thermal Direct plates were reduced to the absolute minimum needed to create an image of sufficient visibility to permit identification of plates for press cylinder placement. Twelve-point type is readable for press placement, but the latent image on Thermal Direct plates does not have sufficient contrast for densitometer measurement. Given the inherent accuracy and repeatability of the CTP process in general, and thermal CTP in particular, most users of Thermal Direct plates have not found this to be an issue. However, this is not to say that Thermal Direct plates are appropriate for every application. Kodak offers several other more traditional plates that permit densitometer measurement and have other characteristics that may be better suited for the specific requirements of a job.
Regarding the run length question, the answer is that the run length any particular user can achieve is highly dependent on press conditions. Kodak arrived at the 100,000 impression run length specification for Thermal Direct plates after extensive testing in a wide variety of press conditions. We are aware that some Thermal Direct plate users have experienced challenges reaching 100,000 impressions. Conversely, we are also aware of Thermal Direct plate users who regularly achieve run lengths of 300,000 impressions and beyond. This is not a situation unique to Thermal Direct plates. It is common to see this sort of run length range with a traditional processed plate. This is not a fault of the plate or the user, but rather a result of the wide variation in press conditions seen in the worldwide printing industry. Again, Kodak’s position is that Thermal Direct plates are not for use by every user in every application. Like all Kodak’s other plate products, the features and functions of Thermal Direct plates must be appropriately matched to a user’s particular presswork requirements.