How to clean an inaccessible Kostiner print-washer plenum?

Steve Goldstein · Nov 1, 2018

My recently acquired used Kostiner 16x20 print washer has a plenum under the print cavity. Water feeds into the plenum, then is forced up into the print slots through tiny holes in the bottom plate and overflows the top. There appears to be some mold or mildew in the plenum that I'd like to clean out as best I can before I use the washer. I've tried pouring in vinegar but it doesn't seem to be doing much, though it was helpful in cleaning (probably mineral deposits) on the accessible surfaces. Any suggestions?

AgX · Nov 1, 2018

I would use instead Hypochlorite salts (chlorine bleach)..

john_s · Nov 1, 2018

I would try an oxygen bleach made for nappies(diapers). The active ingredient (in addition to detergent) is percarbonate which I understand releases oxygen which seems good with organic stains. Used on clothing, it doesn't bleach the way chlorine does. I use it in my Nova vertical slot processor.
I've also used Steradent powder successfully. I think its active ingredient is sulfamic acid which is available as a cleaning product.
Dissolve powder fully before pouring in.
Let us know how it goes.

removed account4 · Nov 1, 2018

hi steve can you get in there with a bottle brush ? i'd unscrew the hose assembly turn the washer on its side
and use a bottle brush and some washing/ baking soda and then some boiling hot water to flush it out ...
you can get a bottle brush at a brew-shop or online at a place like mr beer, or more beer or a chemistry science stuff supply house
plastics are hard to clean because they allow stuff to sneek in ...
good luck !
john

Steve Goldstein · Nov 1, 2018

John, I’m afraid it’s impossible to get in there without smashing the washer. Water feeds into an outer manifold of some sort through a 1/2” or so ID hose and goes into the plenum from there. From the plenum it gets forced up into the print slots through itty bitty holes.

Bleach is the obvious answer and I should have thought of it! Even if it doesn't completely remove the yucky stuff it’ll kill it. I’ll stop in at the market and pick some up.

Thank you.

Born2Late · Nov 1, 2018

Use a 10 percent bleach solution, no stronger.

john_s · Nov 1, 2018

Born2Late said:
Use a 10 percent bleach solution, no stronger.

Good advice. I sometimes use liquid pool chlorine (sodium hypochlorite solution) for difficult cleaning jobs. It's stronger than household chlorine bleaches. I once put a stained plastic kitchen serving spoon (probably melamine) in some that was not diluted enough and it went black and was destroyed. Your washer is probably made of something more durable but be careful.

mshchem · Nov 2, 2018

Vinegar probably killed any mildew. If nothing is coming loose I would use it. I have Dunwright Prowash models. I have setup some surplus Noritsu processor pumps in line so I can circulate water without using any from the tap.
You might try something like that with a mild acid like acetic or citric acid. I would pour in straight white vinegar, maybe warm it to 85 F.

If what's there isn't moving around I wouldn't get to worried

john_s · Nov 2, 2018

When I wash wine decanters which are shaped to make a bottle brush impractical, I soak first with detergent, then put in some raw brown rice and give the vessel a good shake. The rice acts sort of like an abrasive as it rushes past the surface. If your washer is huge it might be too difficult I suppose.

Steve Goldstein · Nov 2, 2018

I ended up pouring about half a gallon (two liters more or less) of household vinegar into the print compartment and letting it trickle down into the plenum through the small jet openings. I collected the outgoing vinegar and ran it through again. And again. And again. Then I filled the print compartment with water and let it all drain out the same way. All in all it took a couple of hours, so I declared victory for now. If I get really motivated some day I'll repeat the process with oxygen bleach.

I wish I could have gotten rice or a bottle brush in there.

David Allen · Nov 2, 2018

The classic cleaning sequence that I learned for everything (trays, automatic processors, print washers, etc) when I worked in a commercial darkroom (conducted every Monday morning as everything had thousands of prints through them during the previous week) was to use:

Farmer’s Reducer part A diluted 1 + 1
Thorough rinse with very hot water
Full strength (undiluted) Hypo Clearing Agent
Thorough rinse with very hot water

In addition to this, the print washers also received:

Ten minutes of Isopropyl alcohol, often called IPA or Isopropanol
A full tank of boiling water which was left until it became tepid and then one complete cycle of water change (monitored by adding Potassium Permanganate).

Bests,

David.
www.dsallen.de

Fujicaman1957 · Nov 3, 2018

Denture cleaning tablets. Add warm water and throw them in and let sit overnight. If they'll clean a toilet below the water line, they ought to clean your print washer.

mgb74 · Nov 3, 2018

My go-to cleaners in this type of situation are:

Oxy-clean (esp. the odorless version)
Chlorinated pipeline cleaner, used in dairy operations

If you want to try the Chlorinated Pipeline Cleaner, let me know.

Steve Goldstein · Nov 3, 2018

The chlorinated pipeline cleaner sounds interesting, but I'm very leery about putting chlorine into my septic system. I may give it a second go with oxy-clean as I need to get some new hose and fittings before I can use it. Truly emptying out the plenum is a chore and a half, though.

jvo · Nov 18, 2018

bleach will etch plastic over time, it will impede water flow. i don't know how long it will take to do so but would stick with vinegar.

jeffreyg · Nov 18, 2018

Has anyone tried CRC? It may not be mildew but deposits from hard water. My guess is that if it hasn't been used for some time and has remained dry the mildew would have dried up. If the acrylic is clear perhaps putting it out in the sun or using a UV light will kill the mildew.

http://www.jeffreyglasser.com/

AgX · Nov 18, 2018

jvo said:
bleach will etch plastic over time

How do you know?
First, there are many types of plastic.
Secondly, for the plastics likely used in such cases, PVC and ABS, I do not see a problem.

Yes, I have had a part of an original bleach container stress-cracking after months of impact of the bleach. In this case the bleach manufacturer used the wrong material for that part.

mshchem · Nov 18, 2018

Steve Goldstein said:
The chlorinated pipeline cleaner sounds interesting, but I'm very leery about putting chlorine into my septic system. I may give it a second go with oxy-clean as I need to get some new hose and fittings before I can use it. Truly emptying out the plenum is a chore and a half, though.

I would just use it. Potable water pipes have all kinds of stuff stuck to the insides of pipes. It stays put unless air gets into the system and knocks stuff loose. Biofilms form in water tanks, usually not harmful. If you are using clear flowing chlorinated municipal water supply, it will be fine.
Go back a hundred years, think about what photographers had to contend with.

Todd Barlow · Jan 17, 2020

My experience today...

I have the same washer and also wanted to deal with the deposits floating in the plenum and building up on the walls of the plenum.
I poured 2 litres of regular household vinegar into the washer and it dripped into the plenum.
After letting it sit for 5 minutes I rocked the washer back and forth to agitate and dislodge the deposits.
I drained the vinegar through a filter with a mesh screen and ended up with quite a collection of debris.
To avoid the build up I stood the washer on end to drain the plenum into the sink.
The vinegar seems to have done the job based on the water and type of build up I have.
all the best
Todd

Steve Goldstein · Jan 18, 2020

Another thing I did after the vinegar treatment was to chase all the teeny-weeny inlet holes in the bottom using a hand-held drill bit. This washer came to me from the Land of Hard Water and about half of the holes were plugged with deposits. I found the drill size by trial and error and don't remember the exact size but it was something like a #56. The holes aren't vertical but at various angles, which made this a very tedious job indeed, and it required patience and a soft touch to avoid snapping off the bit. Now all the holes are all clear. There sure are a lot of them!

I've subsequently modified (I'd like to think improved) the washer so the plenum can drain more easily - I drilled a hole into the plenum wall and tapped it for a nylon bolt. Now I can simply remove the bolt and tip the washer to drain the water out. I don't recall if I used 8-32 or 10-32, it's not critical. I did splurge and get the special drill bit and tap for plastic, and used a nylon bolt with a knurled top so I can remove or insert it without tools.

How to clean an inaccessible Kostiner print-washer plenum?

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