Determing Direction of water movment in print washer.

[gary892]

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

[nitroplait]

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.

[rfesk]

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.

[esearing]

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.

[Paul Ron]

go for it!

[Graham Patterson]

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.

[Duolab123]

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.
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.

[Drew Wiley]

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.

[Duolab123]

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:

[Vaughn]

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...

[esearing]

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.

.

I use 3-4 tablespoons in my koi pond to kill parasites and to help clear the water from organics, followed by a flush of 1 quart of hydrogen peroxide to fully neutralize it and take away the brown color it leaves behind. I buy PP by the pound at a local fish supply house. You used to be able to buy it at Home Depot in the plumbing section, nothing cleans organic waste in pipes better.

[Graham Patterson]

I was using potassium permanganate in school labs at age 11. I think the first use was a standard convection in fluids experiment. Mind you, the physics department actually kept a stock of mercury (mad by today's standards). Those were the days - an English Grammar school that could almost have been Hogwarts!

[Drew Wiley]

Oh, the basement below my high school chem classroom was literally blown up by the one of the class dunces randomly pouring reagents down the sink. The instructor noticed it just in time to tackle him and push him to the floor before a blast came out of the sink. Nearly all the plumbing down below was ruined. The two worst dunces went on to become successful businessmen, one of them an engineer, while the two chem-physics-math whizz kids went on to become a fugitive and a caught 12 yr jailbird with a CalTech degree. Ironic how things turn out. But every little kid home Chemistry Set of the era contained vials of mercury and some strong reagents too.

If one tires of their own darkroom and wants to try collecting fire insurance, well, un-dilute potassium permanganate has its uses. I kept a bottle of it for sake of selective color print dye bleaching - a common practice of the era if nothing else worked. Bad advice. While it did get out a black spot on Cibachrome decently along with neutralization afterwards, now looking at the tiny number of prints where I did that, the "halo" area of the bleach effect has grown about 400% over the past twenty or thirty years from what it originally was. I really wonder about the condition of all those prints by particular lab which specialized in broad area partial bleaching, in lieu of contrast making.

[Vaughn]

I had a pound of Potassium chlorate in the cabinet in my office/stockroom. I did not particularly appreciate having it around, but one prof thought that they might need it some day. Just would be a heck of a lot safer occasionally buying Ferric oxalate with Potassium chlorate already added to it (for contrast control in Pt/pd printing). Once she retired, I think I had our safety people take it away for disposal, as I was/am not into pyrotechnic displays, planned or otherwise, in my office.

It's been a few years, I probably had some Potassium permanganate around, too.

[Daniel Stone]

Tape 3-4in(75-100mm) pieces of dental floss to the inside of your washer, and those can give a pretty good representation of flow/direction. You can also use knitting wool as shown in the video below.



https://youtu.be/75I3mse9Q9Y

[Michael R]

LOL. Prof: “Hey Vaughn I’ll be keeping a pound of potassium chlorate in your office in case I need it. Thanks.”


I had a pound of Potassium chlorate in the cabinet in my office/stockroom. I did not particularly appreciate having it around, but one prof thought that they might need it some day. Just would be a heck of a lot safer occasionally buying Ferric oxalate with Potassium chlorate already added to it (for contrast control in Pt/pd printing). Once she retired, I think I had our safety people take it away for disposal, as I was/am not into pyrotechnic displays, planned or otherwise, in my office.

It's been a few years, I probably had some Potassium permanganate around, too.

[Martin Aislabie]

I have used wet loose tea leaves to try and visualise water flow - both professionally and personally.

Wet tea leaves are almost buoyancy neutral and when they eventually settle at the bottom of what ever you are looking at, a quick stir will re-float them.

The other advantages are that tea leaves are readily available plus they are both biodegradable and non toxic.

The only down side is they can be a pain in the **** when you to try and clean them out afterwards.

If you are going to experiment with different nozzle locations and patterns, it is worth videoing each flow pattern and having a scale visible in the video, to enable flow rates to be measured.

Note - I haven't tried the test in my own print washer (NOVA vertical slot washer) but I expect you will find the flow to be both chaotic and have large areas of stagnation, which then leads you to the question "what are we trying to measure" which may well lead you back to the residual hypo tests and water flow rate v time v water temperature. (Water temperature is critical as it effects the viscosity of the water and hence the flow rate at which turbulent flow begins).

Hope this helps.

Martin

[Graham Patterson]

At last! A scientific use for reading tea leaves 8-) And a nice cuppa while watching the leaves go round and round.

[Drew Wiley]

Guess I'll have to net some water beetles and mosquito wrigglers next, to see how those behave in the washer.