Reply From ILFORD Photo Re : Wavy Scratched Thread
I have put this on a new thread to ensure it does not get 'lost' and so people can see the reply.
I have discussed this thread with our film technical service manager, I will try and give a brief synopsys.
Wavy lines ( meaning marks or scratches in or on the emulsion or on the front or back of the film ) wavy lines we very occasionaly see, these are 'normally' soft chemical based lines or stains, unexplained wavy scratches we have hardly ever seen as complaints ( 1 in 2012 and 2 in 2008 ) why do they say 'unexplained'.... on those three occasions we could not determine how they originated, in over 95% of the complaints we usually can.
The vast majority of scratches we see as complaints are not actually caused during manufacture but during processing or in camera, that is a fact, wavy lines tend to be during processing but of course can be linear, and linear straight scratches tend to be in camera, but you can get wavy lines from cameras as well.
Linear scratches on the film during manufacture can happen, but for them to escape from the factory are very, very rare.
I have already explained the process but here is some detail, I have to qualify this by saying nothing is 'impossible' it is unimaginable that an actual coating line or scratch could find its way into any finished film, when you coat you can get lines ( they are 99% linear, not wavy ) I do not say scratches as they are usually soft lines, any lines or scratches come to that, or any other mark or issue on each coated parent roll is identified by the infra red scanner systems, that 'in line' in production produce a computerised 'map' of the parent roll that then follows that parent roll to finishing and all those 'defects' are cut out of that roll, every parent roll will have defects as they are between 1.5 and 2.5 Kilometres long and over a metre wide.
So the parent rolls that are then slit in finishing are 'clean' and 'defect' free and they then go to make 35mm / 120 or sheet film :
Roll film and 35mm film are cut into 'pancakes' that are 610m long by the film width : 3 full film length samples are taken from that 'slitting' at the beginning / middle and at the end, processed and inspected and if any defect is found the slitting is destoyed and sent for silver recovery. The tested slitting is now ready to be finished, it is then made into the finished 35mm or 120 products, when they make the fully finished films they are then tested again in the same manner to ensure no scratched have been introduced at that final finishing stage. Then finished product from every slitting goes to be stored for the expirery length of the film ( usually 3 to 5 years ) so we can always 're-visit' that film slitting. The 4 digit code on every film identifies the parent roll / the slitting and and the finishing machines.
These are normal finishing QC steps, we have many more tests in relation to the film itself / sensitisation etc, etc )
Technical service tell me that 120 lines are incredibly rare as nothing touches the film surfaces during finishing, 35mm scratches are more common as the film is 'injected' into the cassette during finishing and hence comes into contact with a piece of the cassette ( ie the velvet mounth ) in saying that we would need to put that in perspective, figures would suggest less than 5 justified 35mm film complaints per year are scratches that 'could have been done' in manufacturing.
How do we know what is a manufacturing defect and what 'may' have been introduced after manufacture... well the answer is its not always 100% possible to tell, but usually by lupe and sometime by microscope and on other occasions by electron microscope we can usually determine when the defect or scratch was introduced, for instance anything introduced nearer the manufactured date is softer in the scratch than something later normally is a more delineated or 'harder' scratch.
Sheet film is also cut off pancake rolls but has a different QC method, but has the same number of testing 'steps'.
So what should you do ?: If you have any problem with any ILFORD film you buy and use, and you cannot put it down to something that you can logically explain that you may have done yourself during processing or exposing then you should send the film to the factory, along with the batch number, any packaging and hopefully the full length of film, one simple thing is that if it is a scratch and its through the whole film including whats left in the cassette ( then its not the camera ) or under the tape on a 120 for instance so its good to have the whole film.
We will then examine the film and attempt to find out the cause, in most cases we can and will tell you, we have three results
Cause Justified : A fault during manufacture
Cause Not Certain : We cannot identify the cause
Cause Not Justified : A fault introduced post manufacture
We will return the film as well at our expense if you wish.
All complaints are covered, recorded and monitored as a key performance indicator monthly and by our ISO 9001 certification process.
This does not say nothing ever goes wrong, it can and it does, but it is very rare, and if it does we say so.
Simon ILFORD Photo / HARMAN technology Limited