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I would like to determine the direction of water movment in my print washer.
I want to do this for my own edification.
I was wondering if food coloring would stain the washer.
If someone has a better solution please let me know.
Thanks in advance
Gary
I will be interested in hearing about your results, as I am thinking of building a washer and would like to see the water movement to make sure I have succeeded in building an effective device.
About staining from food colouring, I would imagine that testing on a similar type material should give an indication of the probability, however, a well used washer may have mineral deposits that will be more likely to absorb colour.
I would first try small bits of plastic. The plastic should be as close to the density of water as possible. Not too small. A contrasting color. And washed to remove and debris that may be attached.
That may tell you all you want to know as to flow patterns.
Fluid dynamics are not measurable with food dye, but it can give you a rough idea in the first few seconds. In linear koi pond filters, air bubblers are used to disrupt water flow through a series of mats , because fresh water will take the direct path of least resistance and not always mingle with dirty water or touch the mat. The old tray siphons keep water moving so that dirty water is mingled with clean water and thus diluted . But if you had a way to recirculate the water though a filter you could even use less fresh water intake.
go for it!
The old way to do this was a few crystals of potassium permanganate, which leave strong purple traces as they dissolve. But depending on the flow in the washer the colour will probably even out fairly quickly. Then you would be more interested in how long it takes to flush the colour out of the washer.
This is all subjective, though. Actual measurements would need a flow meter of some sort to test areas in the washer volume, and some means of analysing he dilution throughout the washer (residual colour or chemical content). Which is beyond the scope of the original question.
Yeah, the KMnO3 is mentioned in old Kodak texts.Quote:
Originally Posted by Graham Patterson
I use a magnet drive pump to forcefully circulate water in my archival washers, I pre-rinse the print for a couple minutes then put it in the archival washer. I usually run 3 15-20 minute cycles.
A few drops of food coloring works just fine. Do that using water only, no prints in there. That will do a good job relative to water circulation and the efficiency of water replacement per se, sending the colorant into the supply line and then, after hopefully thoroughly even dispersement, gradually yet entirely out through the drain. What transpires on the emulsion surface of the print itself, and on the back, depends on how efficiently the prints slightly "floats" between the dividing septums, rather than sticking to them. No need for a fancy flowmeter, though if you already have one, why not?
I don't know why anyone other than a gear-loose chemist would want to use potassium permanganate instead. It's a strong reagent in crystal form, and can be hazardous to handle, or even to keep around.
Analytic analysis of prints afterward per residual fixer in a related but different topic, if you're simply so paranoid and skeptical about your washer design that you feel you have to resort to that extra step.
Potassium permanganate is such a powerful oxidizer that sale is regulated. Of course the old Kodak books warned you to be especially careful with potassium cyanide. Yikes!
Mercury, chromium, cyanide, throw in some benzene for ferrotype polish. Crazy.
Kool-aid, red is about the most potent food dye I know of. Of course your prints will smell like strawberries :rolleyes:
Yum! Three color carbons using kool-aid, or better yet, actual Jell-O for color. Blue raspberry, strawberry and lemon. One might be able to tweak the color balance with cherry, pineapple, or other variation.
Prints that smell as good as they look...