Film developers development time

C15-0129. Photographers use a rule of thumb, that a 10° C rise in temperature cuts development time in half, to determine how to modify film development time as the temperature varies, (a) Calculate the activation energy for the chemistry of film developing, assuming that normal temperature is 20 °C. (b) If a certain film takes 10 minutes to develop at 20 °C, how long will it take at 25 °C ... 

Continuous Agitation This method is especially popular among those using JOBO rotary processors. The film is agitated non-stop for the full time of development. The direction of agitation should be varied to avoid streaks or patterns on the film. Development time should be reduced by 20%. 

When a film developing-time range is given it is for films rated by the manufacturer between ISO 100 and ISO 320, unless otherwise stated. To choose a starting time, use this rough rule of thumb For films rated between ISO 100 and ISO 320, use a time in the middle of the range. For films rated from ISO 12 to ISO 80, decrease the development time from the midpoint by 25%. For films rated higher than ISO 320, increase the time from the midpoint by 25%. 

Developing times and ISO ratings are for Ilford FP4+, tray processed with continuous agitation at 68F/20C. These specifications should also apply with slight adjustment to other medium speed films. For slower films, the developing times will need to be reduced by about 10%. For faster films, developing times will need to be increased by about the same amount. 

Real Time Radiography (RTR) is an advanced method of radiography in which the image is formed while the job is exposed to ionising radiation. RTR is often applied to objects on assembly lines for rapid inspection. Accept-or-reject decisions may be made immediately without the delay or expense of film development. The main advantages of RTR are thus, reduction in inspection cost and processing time. 

In order to determine the appropriate development conditions, we examined dissolution characteristics for resist films in the aqueous alkaline developers by measuring film thickness as a function of development time. In Figure 7, dissolution characteristics for the new resist before and after exposure to KrF excimer laser are compared with those for the styrene resin matrix. 

Other variations of film decoration are, for example, the rocker moulding for General Motors Chevrolet Trailblazer North Face Edition, a 2-metre-long part thermoformed over injection moulding because of the relatively low volumes (7000 to 8000 vehicles per year) and the short development time required. 

After a long development time, we started manufacture of the compound by carrying out a mull extrusion. The conditions for mull extrusion are especially important to produce good quality compound. The film processing is only possible when the selection of extrusion conditions is appropriate. The properties of the manufactured film are also affected by these conditions. The conditions of blown film processing for this starch compound are shown in Table 4. 

Solubility Rate Measurements. Solubility rates, Sr, were determined by measuring PBS film thickness as a function of development time. PBS films coated on silicon wafers were broken into several pieces. Each piece was dipped into n-butyl acetate, BuAc, and the development time measured. The film was rinsed in isopropanol and baked at 120 C for 30 minutes to remove residual solvents. Film thickness was measured by interferometry. The temperature of the developer, BuAc, was controlled at 2S C O.OS C and the developer was not stirred or agitated during the deydopment process. Plot of film thickness vs. development time were linear for low Mw films. Films having M, greater than 400,000 g/mole did not completely dissolve in BuAc. 

An interesting observation in Ref. 86 was that the density of nuclei formed in the early stages of film deposition did not change with time. The film developed by growth of the initially relatively small (ca. 20 nm) nuclei. This suggests an ion-by-ion type of growth rather than a cluster one. 

Figure 2. Dissolution curves for positive resists after exposure. The doses are designated by the numbers accompanying the traces. A stronger dose leaves a thinner film at a fixed development time.

Expose the film for a time variable from 5 s to several minutes. It is usual to begin with a short exposure, followed by development of the film, followed by longer exposures, if necessary. 

Electrostatic forces Films are also destabilized by an electric field applied perpendicular to the film surface. This is done by assembling a capacitor device that sandwiches a liquid-air (or liquid-liquid bilayer [28, 29]). After liquefying the film and applying an electric field, the film develops first an undulatory instability (Fig. 1.9a). With time, the wave pattern is amplified, until the wave maxima make contact to the upper plate, leading to an hexagonally ordered array of columns (Fig. 1.9a) [30],... 

Using Sodium Sulfate With D-72 or D-76 By adding sodium sulfate, anhydrous, to Kodak D-72 paper developer or Kodak D-76 film developer, as in the following table, the normal development time recommended for 68F/20C can be maintained through the range of temperatures shown. After adding the sulfate to the developer solution, stir until dissolved completely. 

Almost any panchromatic film made today can be pushed one stop with little or no discernible loss in quality. For example, Kodak Tri-X can easily be pushed to El 800 and Ilford Delta 3200 (which is closer to El 1200 than it is to ISO 3200) can easily be pushed one stop to El 2400. Try adding 25% to the normal development time for Tri-X, and 25% to 40% with other films for a one stop push. With testing and experience, you should be able to capture almost any event on film, regardless of how little ambient light is present. (See Yuette at the Coffee House on page 53 )... 

Develop only one sheet of film at a time or use a sheet film developing tray (see Resources Photographers Formulary). Use the intermittent agitation method I describe in Chapter 4 Agitation and do not lift the negative from the developer until it is time to move it to a water... 

Alternate Dilutions It has been accepted practice among photographers that contrast with ABC can be controlled by altering the amount of carbonate (Solution C).As it turns out, changing the quantity of the carbonate has more of an effect on film speed and development time than on contrast. 

Pyrocat-HD and Pyrocat-MC kits can be purchased pre-mixed in propylene glycol from Photographers Formulary. For detailed information on use, with development times for some films, go to www.photoformulary.com and download the following technical information documents ... 

Nonetheless, there are still a few valid reasons to learn how to develop by inspection. The most important is that it allows complete and total control over every image. A second reason is that it might help save negatives when there is doubt as to the correctness of exposure. A third reason is that when developing films by the water bath method to control contrast it is often desirable to visibly monitor development (Chapter 4 Film Development Water Bath Development). The fourth, and final reason, is there may come a time when film will again be hand-coated with loose tolerances. 

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