DIY archival printwasher again

I have a question. Why do archival print washers, DIY and commercial, use clear plastic for the tank? It is expensive and not that easy to work with. Why not make the tank from plywood waterproofed with epoxy resin like so many DIY darkroom sinks? I am thinking of giving it a go and using the epoxy inside and outside to make sure all of the wood is covered. Any good reasons not to?

I really can't think of one. I made an 11x14 washer from a blue plastic file box. Worked just fine. The bigger issue is keeping prints separated.

I want to make a 20x24 washer as well (though to date I've only done 16x20). So I'm thinking epoxy and plywood. Maybe plastic or glass are used because they're "natively" waterproof. I've been toying with using plywood for the bottom and the thinner sides, and some sort of plastic for the big sides, just to have less square footage that needs waterproofing. For a print washer this size, the bigger challenge will be a design that doesn't warp or bow from the pressure of containing that much water weight.

Col9 said:

I have a question. Why do archival print washers, DIY and commercial, use clear plastic for the tank? It is expensive and not that easy to work with. Why not make the tank from plywood waterproofed with epoxy resin like so many DIY darkroom sinks? I am thinking of giving it a go and using the epoxy inside and outside to make sure all of the wood is covered. Any good reasons not to?

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Clear plastic has several advantages:chemically inert,see through and much prettier and lighter than wood

By the time you buy the plywood, and a good grade that is not warped, and the cost of epoxy, not even counting the labor, I wonder if you will save any money. No reason for it not to work though.

If I was to use plexiglass (or something like that), what kind of glue/sealant would you recommend?

You can get solvent welding glue specifically for acrylics

Thanks for the tip, calebarchie. I think I'll just ask at the store where I can get the plexiglass. I really don't know much about this.

fdonadio said:

If I was to use plexiglass (or something like that), what kind of glue/sealant would you recommend?

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weld-on 4 and weld-on 16
4 is water thin and applied with a syringe type applicator
16 is thicker like syrup and can be applied directly from the tube. handy for filling small gaps. Get the larger tube. I buy all my stuff from amazon or ebay.

You'll need either a plastics cutting blade for your table saw or a high quality spiral router bit and router with very little runout that you can use to smooth out your cuts.
The seams need to be very smooth to get a strong enough bond to be watertight under pressure.
I wouldn't say acrylics are difficult to work with, they just require very precise methods.

You mean the surfaces being glued have to be smooth? My experience with adhesives show that some "texture" is necessary to have a strong bond.

fdonadio said:

You mean the surfaces being glued have to be smooth? My experience with adhesives show that some "texture" is necessary to have a strong bond.

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Yes. Watch some youtube videos. Take a look at some commercial print washers for fish tanks.

You're basically building a tank. The usual approach to this is plex or glass, as in aquarium building or sheet metal (ss for photo applications!). There's a lot of technology for building both plex and glass aquariums to be had, so look into that. For what it's worth, I built a whole lot of acrylic aquariums with the glues mentioned above and only had one failure (55gal tank that split a seam; it was fine after repair, but I lost a couple of sensitive salt water fish...). Anyway, it lasted years before that and was easy to repair. If it had been a print washer and in the sink, it would have been simply an easy repair project.

Dividers for the print washer are the design challenge. A lot of makers use thin plastic dividers held together by a frame or spacers of some sort, or a basket. I've used both sheets with spacers and a frame with thick monofilament (think weed-eater line).

FWIW, I found that the cost and time needed to fabricate my own washers about equal to buying a new Versalab. Their washers are opaque plastic, not the prettiest, but totally functional. I have their 16x20/20x24 model. For smaller prints I now have two Paterson 11x14 washers that I've modified a bit. They are pretty cheap on the used market these days. Maybe you don't really want to build one?

Best,

Doremus

I don't know about the OP, but I live in Brazil and stuff is expensive here.

It's very hard to find used lab gear to buy and our "big auction site" is full of junk being sold for their weight in gold. For example, once I saw an old, rusty, Durst L1000 missing lots of parts for $500 (USD)!

Import taxes are hefty and shipping costs one arm and a leg for bulky or heavy items. So, importing from US or Europe is not always a good idea.

I believe my best shot is DIY. Without a doubt, it will be a lot cheaper and I won't lose lots of time looking for a decent washer.

I asked about plexiglass out of curiosity and to try to help the OP in finding a solution for his DIY washer project.

Maybe plywood with epoxy is not such a bad idea.

Thanks, wildbill! I'm gonna look at some videos about plexi fish tank construction!

Take a look at this.
http://youtu.be/qDWNRUWlf5Q

Mainecoonmaniac, thanks for the great video. It sure is a cheap way to make a big washer! For big prints (16x20" and 20x24"), it seems to be awesome!

That guy's a genius

fdonadio said:

Mainecoonmaniac, thanks for the great video. It sure is a cheap way to make a big washer! For big prints (16x20" and 20x24"), it seems to be awesome!

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I think his solution requires the least amount of expense and specialized tools. Found this video a couple of years back because I needed an efficient way to wash fiber prints. California is going through a severe drought and I had to change my way of washing prints. I was using an old Arkay tumbling print washer. It used a lot of water and inefficient. I didn't ending up making one, but bought a used archival print washer on Ebay.

Mainecoonmaniac said:

Take a look at this.
http://youtu.be/qDWNRUWlf5Q

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That's similar to my 11x14. Research into washing has found that moving water is as important as water changes, and I also used a small fountain pump and tubing to keep the water moving along the print surfaces. So, fill it up, recirculate the water for a while, run more water so the water changes out, etc. A lot less water is used than continually running water through the washer.

But - finding a plastic container suitable for 16x20 or 20x24 - that's tough, unless you expect to wash a dozen or more prints at a time. I haven't found anything tall & skinny enough. As sizes increase, they increase while keeping a basic 'shoebox" proportion. The other problem with these containers is as they get larger, the weight of water makes them bow out significantly - they're not designed for water.

I have enough scraps of oak plywood in my storage to make the bottom & sides (A big "U" maybe 10" deep, by, say 26" wide and 22" tall) - I don't buy the idea that plywood and epoxy paint is cheaper than a decent thickness of plex, and my local big-box sells birch ply in 48" squares for about $25, far less than a sheet of decent weight acrylic.

My musings have been to make the big "U", with maybe a rabbeted edge where the plex side sheets would nest. These would be glued in (epoxy? Silicone?) and screwed in as well, with the screw holes being epoxy filled, so the entire wood surface is sort of enveloped in epoxy.

From there, I'm assuming I may need to do something like a band of 3/4" square aluminum tube around the circumfrence to keep the thing from blowing apart when full of water… though maybe thick enough plexi/acrylic would be fine.

I've seen separators made from plastic deck-lattice material (like wood lattice for fences and decks, but molded from PVC to look like wood painted white) and also the textured plastic used in fluorescent ceiling lights. I assume these could be spaced with something like 1/4-20 threaded stainless rod (heavy so they'll sink vs. float) with nylon nuts (you can buy nylon threaded rod in standard thread sizes, but my 11x14 needs the print separator glued down - it floats.)

That's as far as I've gotten thinking about this one.

{EDIT} - By the way, most DIY articles go on about designing with bottom drains "because thisoulfate sinks" - it doesn't. At these quantities, it's in solution. Design for full circulation with no dead spots.

I thought the same thing

M Carter said:

That's similar to my 11x14. Research into washing has found that moving water is as important as water changes, and I also used a small fountain pump and tubing to keep the water moving along the print surfaces. So, fill it up, recirculate the water for a while, run more water so the water changes out, etc. A lot less water is used than continually running water through the washer.

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I'm guessing as long as the used wash water's concentration of fixer is relatively low it can be "recycled", pumped back into the print washer to work again. My first wash setup was a two tray system with a tray siphon. I'd have one tray on top of another. The top tray had the siphon and the bottom tray caught the tray siphon's used water. The bottom tray would hold prints that have been fixed and the top tray had the fresh water. Now with the drought, I can't use tray siphons or my old Arkay tumbling print washer anymore.

I'm still working on more water efficient work flows in my darkroom. I'm starting to feel guilty washing FB paper in my darkroom. I'd rather not use RC paper to save water either.

Mainecoonmaniac said:

I'm guessing as long as the used wash water's concentration of fixer is relatively low it can be "recycled", pumped back into the print washer to work again. My first wash setup was a two tray system with a tray siphon. I'd have one tray on top of another. The top tray had the siphon and the bottom tray caught the tray siphon's used water. The bottom tray would hold prints that have been fixed and the top tray had the fresh water. Now with the drought, I can't use tray siphons or my old Arkay tumbling print washer anymore.

I'm still working on more water efficient work flows in my darkroom. I'm starting to feel guilty washing FB paper in my darkroom. I'd rather not use RC paper to save water either.

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Well, it's not about relatively low or high (except for two-tray scenarios, but talking washers here) - it's about when the amount of fix in the paper reaches equilibrium with the fix in the water. When it hits that stasis, fixer will stop moving around.

But how long does it take for, say, a print that's had 2 changes of water to release (for instance, throwing randoms around) what is 50% less fix trapped in the paper than on the first tray of water? Is changing the water after 5 minutes a waste (IE, does the water have room to absorb more fix)? And is leaving the paper in for an hour a waste of time (IE, stasis was reached 20 minutes ago and it will take fresh water to get the hypo levels in the paper to drop). I'd assume the first change of water should be done much sooner than the 2nd and third and so on.

Agitation (or circulation) speeds up the time it takes (as I understand it) to reach equilibrium. But the actual time is based on how much water, how much fix is in the paper, and how efficiently the fix is spreading from the paper to the water. Now, I can only guess at that stuff, though I suppose there are tests that could be done to the water. But once the water reaches stasis, you can wash all day and you're just moving fix around from paper to water. The paper will always have the same amount of fix in it.

Wash water is, basically, very weak fix -until the fix is all gone.

But (if the above is correct) it would mean for each change of water, you need more time for the water to reach stasis with the paper. So my rough strategy has been fill the washer, let the pump recirculate for 5 minutes or so, open the drain and add water for a few minutes, and do that several times with the time intervals increasing.

Or sometimes I'll just open the drain to a trickle, and trickle the same amount of water in for 30 minutes or so, then do a full change, recirculate for 20 minutes or so, then repeat the dribble in and out scenario. So I may use 3 or 4 washers full, but it seems way less than full-on running water for an hour - and my prints test clean. (I usually throw a scrap print in and use the residual test every 15 minutes or so to get a feel for how it's all going).

I think for many of us, "sort of guessing" at wash times and erring on the side of wasting some water guarantees us clean prints (the guys who soak in a tray and change the water every 15 minutes for 90 minutes - maybe they're wasting half of that water??). But with water shortages and droughts, someone may need to come up with an easy way to test hypo levels in wash water (I guess there are some ways to do that but maybe there should be something no-brainer and cheap, like test strips that come with the fix when you buy it?) that tell us precisely how much fix is in the water??