prewash

[mikeivnitsky]

Some people recommend a prewash and some advice against it.They

explain it as removing the first(halation) layer from the film.

 

What is the actual effect?

I usually use ilford pan 400(no prewash) and develop it in tetenal

ultrafin liquid,stop with ilfostop and fix with ilford rapidfixer.

[jay_de_fehr]

Hi Michael.

 

I belong to the no-prewash camp. I've never seen any benefit from it, and don't see the point in another step in the process. If I had a problem that was solved by a prewash, I'd gladly endure the extra step, but thankfully, that is not the case.

 

Jay

[nikos peri]

I belong to the clean camp - I wash. For one, I'm a believer that it promotes a more even

development by making the emulsion replace the water with developer uniformly. There are

heaps of debates about whether this is true in effect, but it can't harm...<p>

But mostly, I can get a substantial temperature jolt in the developer if I pour it into a warm or

cold tank. I tend to dry my reels with a hairdryer before loading them, so they're often quite

warm. The pre-wash has the benefit of bringing the tank and reel and film down to the

starting point of 20 degrees.<p>

And finally, don't you love the cool colours that come out with the anti-halation layer?! ;-)

[stephen gale uk]

I pre-was my film.

 

I find that it gets rid of more of the anti-halation layer and that "purple tint" to the finished negative. However, it is arguable that increased washing at the end of the process might have a similar affect.

 

However, the main raise is to get the tank, and it's contents, up to about the right temperature.

[rdkirk]

I do pre-wash.

 

Primary reasons: To promote in a non-active step more even distribution of developer, to eliminate in a non-active step the airbells that can form when a solution is poured over dry film, to bring in a non-active step the film and tank to the same temperature as the processing solutions.

[hilander]

OI also pre-wash for 2 minutes. I was having a problem with airbells, and pre-washing fixed

the problem for me.

[profhlynnjones]

Hello Michael,

 

The advantages are questionabl at best, but if your techniques are good, it also won't hurt anything. If you are using drum processors, Pre Soaking can be very helpful in maintaining developer temperatures.

 

There is no antihalation backing in 35mm still film, the plastic base is simply dyed grey with a density of nearly 1 f stop and it can't be removed.

 

roll and sheet films do have an anti-halation backing, the dyes of which can be washed out. Some users of replenished developers like to pre-soak with water just to remove the dye making the developers less colored.

 

This had no effect on the thin emulsion films which have a slight color after processing. This can minimized by doubling the rapid fix times. Delta 100 Rapid Fix for 8 minutes, all others for 10 minutes. These thin emulsion films also "wear out" much faster than conventional films.

 

Lynn

[michael erlich]

Jobo recommends a 5 minute prewash with all B&W developers except Xtol when used in a rotary drum with continuous agitation. A prewash, in addition to stabilizing the temperature, brings the development times more in line with the times for intermittant agitation. Otherwise, a significant reduction in development time is needed with rotary processing, about 15-20 per cent. With an active developer, such short development times may be problematic.

[don_mckeith]

I don't pre saok,unless I'm using Efke 100 (usually the PL)--

 

for this film I find pre soak necessary for even development.

[chris_waller]

In times past I used to get the occasional outbreak of uneven, mottled and streaked development so I started pre-soaking and since then, touch wood, I've never had a problem, so I continue to pre-soak. I trhink it's more an article of faith; some pre-soak, some don't; and both camps can get prefectly good results. Whatever the case, I pre-soak for 2 minutes, being as precise with temperature and time as I would for the developer.

[daniel_gregory]

I don't always prewash it depends on the film and developer. I pre-wash all my 8x10 stuff,

but in smaller formats, I only prewash if I am doing a pyro development or shooting Forte

film. The pryro exhaust to fast on the film, the prewash softens the emulsion to ensure even

development. My Forte film always requires a prewash or it seems to develop mineral stars

and other various issues, but Trix and Acros all seem fine without the prewash.

[omar_ozenir2]

I started to pre-soak film a while ago. I began doing this after I started to get air bells on some of the 120 film. With pre-soak, the problem disappeared.