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Opaque Film Positives

Posted on Mon, 5 Mar 2007 at 11:27



We have RIP software and waterproof inkjet film that enable you to achieve extremely dense film positives.

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Bill Hood says: It is not the opaqueness of the film's maximum density that you should be worried about as much as the amount of UV energy that is being transmitted by your exposure source and the minimum density, i.e. ...

It is not the opaqueness of the film's maximum density that you should be worried about as much as the amount of UV energy that is being transmitted by your exposure source and the minimum density, i.e. clear area of the film positive.

Always remember that the UV exposure source should be in the 380 to 420 nanometer range to fully harden the emulsion in the shortest possible time. Exposure sources that fall outside this range, i.e. fluorescent lamps, quartz, etc, will produce a longer exposure time that allows energy to be transmitted through the opaque areas of the film positive.

Let's not lose sight of the fact that the purpose of exposure is to harden the emulsion through the clear areas of the film positive. If the clear areas are transparent, approximately 96-percent of the light will be transmitted to the emulsion. This allows the emulsion to polymerize quickly and efficiently. Conversely, if the positive has a semi-transparent, foggy minimum density, the exposure will have to be lengthened to fully harden the emulsion. This extra, needed exposure will present consequences to the opaque areas of the film positive causing light to creep around the edges. Fine lines may disappear and if the film is very cloudy, the light may penetrate even the most opaque areas of a film positive.

Do yourself a favor and only work with film positives that are extremely clear so as to render the fastest exposure time.

Bill Hood
Billhoodconsulting.com

posted on: Thu, 09/18/2008 - 5:56pm

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