Recipe above gives you a lifetime supply of course.Įarlier post on this thread was wise. It adds a slippery element that prevents spotting. I heard about this recipe, but never used it.ĥ gal water (danger.your water might not be as clean as you think.)Įvidently the key is the glycerin. Many decades of work in commercial/pro labs. The fact that Kodak doesn't use it should tell you all you need to know. If detergent or soap worked as a wetting agent then Kodak would use it. The bottom line is - use the proper stuff. It tends to leave the neg along with the water - any residue is undetectable. This compound has a relatively small molecular size, is chemically inert and is pH neutral. Wetting agent is normally ethylene glycol (it's used in car antifreeze). People who use soap or detergent and claim it works fine usually use it in such incredibly low concentrations that it does not actually do anything. In both cases they have to be used at quite high concentrations in order to work effectively and this results in a sticky coating of soap/detergent remaining on the neg. In addition, detergents contain other compounds designed to do different things - remember that they are designed for washing greasy dishes - which themselves decompose. In addition, soap reacts with the dissolved salts in tap water to form an insoluble scum which can end up on your neg.ĭetergents are manufactured from oil and are complex long chain molecules which again can break down over time. The mixture decomposes over time to release sulphur and other nasties detrimental to your negative. To make it pH neutral you have to add an acid. I use a syringe to measure out the PhotoFlow after calculating the quantity needed.Soap is made from animal fat and hydroxide. Whichever way it's done, tank or tray, the 200:1 ratio for different film sizes, still needs to be pretty accurate. I sometimes do it that way, and sometimes pour it into the tank without the top on and agitate for a minute using the twiddle stick. You can of course mix just one quantity for a tray and slide the film through it. Another requirement I've found is that's fairly important is to calculate accurately the 200:1 for all the different quantities for different size films. It can be more economical that way if you have more than one film to develop, that is if you're doing the films one at a time. A 200:1 mixture is supposed to be "one-shot", used once then discarded, but I've used the same mixture twice for two nights running and then discarded it. For water I use is demineralized water I buy at the local car accessory/parts shop, it's battery water, batteries hate minerals and contaminates. Water marks could be from a mixer that's too weak, or drying the film too quickly. Is there an "expired" date on the bottle ? Mine has "Exp: 2016/18" but it's still working ok. Things like the filter cartridges are made of HDPE, while a lot of the plumbing on the system is PTFE. The one 18MΩ/cm system I look after(ultra high purity, aka "nanopure") is fed the "house" DI water and steps it down via ion exchange plus activated carbon and physical bacteria filters. That delivers "standard quality" 1MΩ/cm(generated by ion exchange resins from tap water, and also hit with a germicidal lamp and filtered). Our system at work(which was installed by a since-deceased person in the department) is all done with HDPE tubing, and some back of the envelope math tells me that it should be right at 3/4 miles of tubing give or a few hundred feet. Presumably whatever was in the HDPE didn't do that.ĭI water can be a bit funny in what it is capable of dissolving. Switched back to the #2 plastic and.Dry marks are all gone ! Any chemist around on this "bit" ?īest guess would be that the PET had a plasticizer that would at least disperse if not dissolve in the DI water and then end up as a deposit on your film. Putting the little grey cells into action, I realized the DI was being delivered in #1 PET containers, vrs the "old fashion" milk jug #2 HDPE plastic. Anyone want to comment: Until about two months ago, I have never seen lite, feathery drying marks on my film after using Photo Flo & a DI "mist spray" since the late 80's.
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