Last edited by Pere Casals; 29-Aug-2019 at 03:43.
Pere:
The critical issue that has been overlooked in this thread is: What quality controls - if any - did the vendor undertake to assure that the liquid Pyrocat, and in whatever configuration your ordered it, was capable at the time it left the vendor to develop film to the standards established by Pyrocat's inventor Sandy King?
What I find unacceptable is the idea, and without warning, that the product's end user must assume the risk that the Pyrocat as purchased does not meet its claim of fitness for its intended use. Indeed, what is especially unfair in my opinion is that Sandy King's authorized re-seller does not offer a money-back guarantee for Pyrocat, if the product does not perform as advertised .
In this regard, I do not believe end users should be expected to pay for the product, and then expend the time to do the testing work of the vendor. As for me, I have switched to powered Pyrocat-HD and as sold by Bostick & Sullivan.
In this regard, I have eliminated at least the possible "liquid" component of the many reported instances, and as documented on this forum, of the "Sudden Death" of Pyrocat when used to develop sheet film. As for the claim that unopened plastic bottles of Pyrocat-MC have a self-life of more than four-five months; in my experience I have found that claim to be untrue.
Flauvius
If concentrate is made in water you cannot dry out the empty volume on top, you will have humidity around water's vapor pressure, 2.34kPa at 20ºC, IIRC, coming from the water's surface.
N2 is very good, butane is even better. Butane is also flamable, of course.
If you can mix your own, I would consider mixing up Pyrocat HDC or PC in glycol, as these need little or no heat and no water to make. All you do (if you can be patient) is put it all in a bottle and turn upside down everyday for a week or so. If you can avoid heat and water, mix in glycol and store in glass bottles they should last 5-10 years.
That is true. It is harder for humidity to form in the presence of N2 though. The N2 would prevent the liquid from evaporating which would allow the formation of O2. I use Argon myself. So long as you ensure positive pressure, ie, gas is flowing out past the bottle opening and then cap it you would be fine.
Nitrogen is preferable as it displaces oxygen and why it is used in almost industries to purge systems of moisture and combustible gazes. Argon is also good at this.
I find this amusing since they ship cachetol in a plastic container with what looks to be electrical tape sealing the lid onto the base container. This is from the technical sheets at PF:
Catechol (pyrocatechin) has a high vapor pressure and it is a phenol. The high vapor pressure means that solid catechol
evaporates readily. When you open a bottle containing solid catechol, you can smell it. Always store the solid catechol in a
tightly capped glass container. When mixing a solution containing catechol, work in a ventilated area. When catechol is in
solution, its high vapor pressure is not a problem.
The magic you are looking for is in the work you are avoiding.
http://www.searing.photography
It's probably not practical to ship chemicals in glass containers.
Really? Then how do grocery stores get the isles full of pickles, jelly, milk, salsa, beer, wine, and dozens of other products in glass jars/bottles? Or how would I ever be able to get a glass jar to my house to put my chemistry in? It may not be cost effective compared to plastic, but I doubt it would be that much more for this industry. And it would be more environmentally friendly than me throwing out the contaminated plastic jar.
The magic you are looking for is in the work you are avoiding.
http://www.searing.photography
I don't remember the exact rules, but if it's not a safe chemical to spill, and has a hazmat sticker on it, even something electronic with lithium batteries, it has to meet special shipping requirements. It must be able to survive at least a 2m drop at any time in any orientation, be crushproof, pressure change proof, etc... Plastic/metal is much more suitable for this. Jars of food or empty jars are different in that there is not a risk from the spill. And long term food products are probably not flown, reducing regulations.
At least reagent grade chem can be found in both plastic and glass containers.
There are several factors.
First it depends on the compatibility of the chem with glass and with plastics. Sending several big glass bottles in the same packaging it can be risky and extra care/cost should be added, we all know that some chem can be super toxic, extremly corrosive, flamable... and a broken bottle can be a funny party.
Then we have very bad plastic bottles that are penetrated by air, but also we have very good plastics that provide a tight barrier for gasses. In particular, even soda/coke type bottles are very good, because they are designed to not leak CO2 inside, under pressure and for years, some can resist 20 bar while they are flexible, so they can stand drops, accidents, etc.
A large glass container is very fragile, a 100ml one is less a problem. Size matters a lot in the decision.
Of the chem I see, concentrated sulphuric comes in glass, dichromate comes in plastic, Erythrosin B 10grs in glass... I guess this is not by chance, each chem/volume has an optimal container for a certain usage, but IMHO plastic is used a lot because a fall of the container doesn't end in a decontamination protocol.
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