It's been suggested to me that I ought to filter the water before adding it to the developer, not because of any apparent issues with my negatives but as a precaution.
I see Paterson make a specific filter but I was wondering if i could use the paper type coffee filters as an alternative.
All municipal water supplies have dissolved solids: sodium, potassium, iron, sulfate, bicarbonate, carbonate, iron, etc. It is relatively high concentrations of these elements/molecules that make for a 'hard' water. (Think of areas in the southwest US.) The coffee filter will not retain/capture such agents as these because they are DISSOLVED in the water. A coffee filter passes coffee and retains the grounds. The brown color of coffee is--you can guess--dissolved solids. Coffee filters are indeed designed to retain grounds and pass coffee and will pass the dissolved constituents in your water. We have two choices: 1. Buy a reverse osmosis filter, 2. buy water with low concentrations of these constituents, and 3. just work out the development times needed for your specific water supply.
Peter Collins
On the intent of the First Amendment: The press was to serve the governed, not the governors --Opinion, Hugo Black, Judge, Supreme Court, 1971 re the "Pentagon Papers."
Any benefit would depend on your darkroom's water supply quality. I have since 1979, final rinsed B&W negatives and mixed wetting agent in distilled water or bottled "filtered" water and ignored water quality of the other steps. All chemistry components I use indicate mixture with tap water on the instructions. But I have always lived in an area abundant in fresh water. I did place an in-line filter in my darkroom about 5 years ago, but can't say I ever had a problem before I installed the filter and I'm reluctant to stop using the distilled water, though one would think with the filter I'd be fine. If you ask me these home-grade water filters (like the one I installed in the picture) may not do much. Like, how would one tell how well it works if there was no problem before?
For years I have just bought gallons of distilled water from one of the mega stores when it was on sale. Store it on a shelf in my darkroom. Ambient temperature in the room is 68 degrees so after a day or two of storage the water is that same 68 degrees. I use well water for everything except film developer. Cost of using bottled distilled water to mix up the film developer has to be a fraction of the cost of the film...
A coffee filter won't remove the finest suspended solids. Also, unless you cut it into discs and mount it in a holder, you're limited to a rather small depth of water above the filter, so the rate of flow is bound to be small. That said, I've used a coffee filter to filter my one-litre bottle of fix, but only when my stock of proper lab filter papers ran out. I haven't noticed particles in my mains water; I only filter chemicals to get out dust they pick up from use, plus any precipitate they have developed.
An in-line filter like the one ic-racer showed would let you choose your filter element, from a range of different exclusion sizes; and you can apply up to the whole mains water pressure to push the water through, so you can treat water at a decent rate. Not too expensive to set up, but as he says, you probably want to be sure you have a problem first.
In a previous life I worked in a research lab, and some of my work was on water filtration using ultrafiltration membrane filters. The process was for removal of natural brown colour in upland water, from peat. However, the membranes we used would also remove some (not all) of the dissolved hardness; sort of half-way to distilled water. If I needed large quantities of purified water, I set up a filtration process to make it, rather than taking over all our limited distilled water supply. If I remember right, I ran that at about one bar of pressure.
Come to think of it, what we called 'the still' was actually a membrane filter, followed by a gel deioniser. That ran at about six bar.
It's an extremely simple process to distill your own water.
http://www.wikihow.com/Make-Distilled-Water
I do the same, but I also mix TF5 per instruction with distilled water. Smells less they say. I can't tell.Originally Posted by Greg
I now buy the expensive distilled grocery store gallons, cost $0.25 more, but the bottles don't leak. I had 20 gallons of Roundy's store brand all spring! leaks right through the bottle in various locations. PITA
I also drink it chilled, tastes great.
I did the math on DIY and Distilling machines. Store bought wins hands down in total cost to user. I buy 6 gallons every visit to the store. Delivery in 5 gallon bottles is too expensive. Except in Winter, I order 10 gallons of Distilled from PeaPod. I tip.
Tin Can
A charcoal filter over a coffee type filter is excellent, but I have a distiller anyway and use it for chemical mixes. For photo-flow and stop bath I use the charcoal filtered tap water.
For me, distilling water equipment would be about 0.50/gal for electricity + equipment + time, so I just buy it for <$1/gallon when I happen to be at the store. I'd have to use a few tons of it to make the equipment worthwhile. I use it for concentrates I expect to keep a while, like mixing developer concentrate, fixer, etc.. For one-shot working solutions, I just use tap water.
Coffee filters do have some effect in cleaning up fixer though. Sometimes that can get silver crud in it well before it's ineffective. At least for tf4/tf5 fixer.
I routinely use Melita #6 white coffee filters in a funnel after mixing dev. while making working solutions, as there is usually some dirt or foreign matter in dry chemicals and this will filter it out... I will also filter the solutions returning to the bottles after use as they can pick up sludge or debris during process... You can see the debris on the white filter paper while using... And if solutions sit too long without filtering, there can be sludge forming in them... Practice folding the cone in different patterns with the apex towards the funnel opening, and you will find a pattern that will pass solutions fairly quickly...
Using a larger cartridge water filter on the water line near the outlet works well... But don't use too fine of a filter, as this seems to start releasing chlorine from the water with a milky solution and fizz, with a chlorine odor...
Steve K
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