Determing Direction of water movment in print washer.

[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.

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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.

[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.