Friday, 30 November 2012

Print washing

Wash tray

For some time now I have been looking for a way to improve my print washing. This is more to do with how well they are washed when I have a batch of half a dozen or so processed prints. At the moment I use a homemade tray that is sloped, with running water coming in at the top and is dammed at the bottom to create a reservoir before flowing through holes that control the level. But this only allows me to wash a couple of prints at a time which needs to be agitated now and again by hand. The solution would be a slot style washer.

This has been a thorn in my mind for sometime, that now needs to be removed. So before I build a new one I should do some research. I started off by asking a question on the FADU forum about slot widths to get an idea of what the average size maybe but not necessarily the optimum. This led to a post by another member pointing me in the direction of Martin Reed's Mysteries of the vortex research (part 1 and part 2) on how slot style washers work. It is quite an illuminating read but was a bit heavy going in places.

First of all we need to go back a step to the fixing process, because what you do here has a big bearing on how well and quickly your prints are washed. I prefer to use a rapid fix which is a plus point but it needs to be timed correctly. Next it is a good idea to place the newly fixed print straight into a water bath and agitate for a minute before placing in the hypo clearing; which is a must for FB papers in reducing wash time. ( I no long use Hypo clearing because my new wash method has shown it's not needed) When it comes to RC papers I exclude the Hypo as the papers absorption rate is next to nothing.  No matter what paper I'm using they all go into a water filled holding tray until I have finished a number of prints. It just so happens that this is a good move. While the prints are in the water the Thiosulpate salts are being leached from the the papers.

It is a myth that it takes longer for the salts to be removed from the fibres of FB paper because it gets embedded. In fact it is the emulsion side that resists their release.  In most cases the fibre side is at archival standard long before the emulsion side. Another very important factor in ensuring well washed photographs is the flow of water. There is an optimum rate meaning less is quicker and more is slower. The water needs to be running fast enough to make a swirling motion this helps to wash the print evenly removing the salts from the  paper as a whole (a type of hydraulic agitation). If the water is running to fast the edges will be washed to archival standard and not the middle increasing the amount of time needed to complete the wash process, wasting water. It does not require a large quantity of water to wash your prints to a very high standard. You can achieve this just by rocking a tray of water backwards and forwards with half a dozen changes. Something I'm trying to get away from unless you have a rolling table that does it for you in which case all you would have to do is change the water.

When I embarked on this research I had not envisaged how complex the wash process was. I suspect not many others give it the consideration it needs either.

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