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Old 06-05-2008, 01:33 PM
Ian Robinson
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On the hunt for a Forming Gas supplier

Am considering playing about with hypersensitised 35mm film again , but lost in a move my old Lumicon Forming Gas Cylinder .

Anyone out there still doing their own film hyposensitisation ? Who do you get your forming gas off , and what size bottles do they provide ?

Been many years since I did any hyposensitiation , and I no longer have access to a chemical laboratory , I used to be able to (with the permission of the chief chemist at BHP Newcastle Steelworks) make my own forming gas from dried Hydrogen and dried Nitrogen using the laboratory gas mixing station. Can't do that now , the lab is gone and I no long have access a lab where I can do this.

Last edited by Ian Robinson; 06-05-2008 at 08:54 PM.
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Old 06-05-2008, 03:49 PM
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Try BOC gases, they do a whole range, give them a call and see!
I don't and have NEVER done hypering of films. Its becoming a lost art i think, good to see someone giving film a 2nd chance! Good luck!

Cheers!
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Old 06-05-2008, 08:59 PM
Ian Robinson
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Originally Posted by Outbackmanyep View Post
Try BOC gases, they do a whole range, give them a call and see!
I don't and have NEVER done hypering of films. Its becoming a lost art i think, good to see someone giving film a 2nd chance! Good luck!

Cheers!
Never abandoned film .... not yet converted to digital astrophotography .... will have a go at that when the 40D arrives .

I think there are things you can do with film a lot better than with digital , and digital still has a way to go to catch up with film resolving power.
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Old 09-05-2008, 04:35 PM
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Yes, try BOC. CIG also use to make it up.

The last time I had some made up was a long time ago.... The problem these daze is you buy the gas for $100 and then they charge you $300 a year or more for the cylinder 'rental'.

What can be done with gas is buy a few new LPG cylinder (they are $35 from Bunnings) and then transfer the gas over and return the BOC cylinder. Of course you have to take into account that the BOC cylinder is at 2000 psi and the LPG is only about 300 or so (need the check what they are rated at... and also have a gauge on the LPG to check that you don't overpressureise it), so you need 10x the volume of LPG cylinders. You also need to flush out any air from the LPG cylinder - I use a vacuum pump and then fill it with the gas and then suck it all out again before filling it properly.

I just had a look at a small O2 cylinder here - it's about 12 cm diameter and 40 cm high and holds 2.2 litres at 16.6 MPa (2300 psi). From memory, a BBQ type LPG cylinder is about 20 L and is tested to .. about 3 MPa(???) and rated to about 1.5 MPa??? (about 225 psi). So allowing for a few losses while flushing, the gas from this little cylinder should just fit in a LPG cylinder. Of course, your not actually allowed to do this....
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Old 10-05-2008, 12:37 PM
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Ahhh, I was in the process of building a hypering chamber when Kodak announced the death of 2415 TechPan... never finished the project.
Still mourning....
Would be nice if one of the other film producers(like Efke or someone) picked up the rights to it, kinda like that German mob thats now making Rodinal to AGFA's original recipe.


My plan though, after quite a bit of research, was to use pure hydrogen ala the Kodak tech papers.... was gonna get the hydrogen from electrolysis of water. Maybe you could try that?
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Old 14-05-2008, 06:44 AM
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Just get the pure H and leave the N alone. I owned a gas company for many years and we actually sold it to BOC so I am quite familiar with the concept of decanting gas from one cylinder to another.

You could theoretically transfer the gas from a high pressure cylinder to a propane bottle but you will need the correct high pressure regulators, not oxy/acet regs which are low pressure. Never do it without a regulator! The safety valve in the propane bottle will vent at about 225psi but please do yourself a favour and leave that method alone, while it is an inventive solution using easily available items, it's just not desirable for safety reasons. Let sleeping dogs lay.

Catastrophic failures with compressed gases can be deadly. There is an enormous amount of potential energy available that can create shrapnel and flying debris. This is what could happen transferring H and N which don't liquify under pressure.

Failures due to hydraulic pressure are not quite as scary because when they fail the pressure instantly drops and liquid gas is not elastic and has not got the same potential energy.

If you had a faulty pressure gauge and sticky safety valve, you could literally blow up (as in bang with flying bits) the receiving bottle many times over with what is in the supply bottle.

I actually had a couple of forming gas bottles (G size). They were made for some other commercial application by CIG (in those days) and I can't remember what happened to them. I guess they went back to their owner.

You could call their specialty gases division and ask if they have such a mix in maybe a D or E size - call 131 262. Don't bother calling it forming gas they wont know WTF you are on about. Just refer to the ratio of the mix and see what they say.

I miss the good old film days - I used to hyper film and it was much more romantic and less clinical than digital astrophotography.
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Old 15-05-2008, 09:48 PM
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I've worked with gases as a chemist and then later as an engineer and am well aware of the risks involved with high pressure gases.

Not something to mess with unless you are properly trained and have the right gear.

I am reluctant to handle high pressure H2 gas , it's too easy when venting and mixing gases for static eletricity or a spark to cause ignition to happen (we had strick gas regulation and continuously monitored H2 concentration when I was using the gas mixing station, and when involved in gas plant. The reason for mixing H2 with N2 is to reduce the possibility of an inadvertent ignition. I used to know the LEL and UEL for H2 in N2 (or air) and this info is readily accessible in any good combuston engineering handbook.

The gas needs to be dried too , one of the main reasons for hypersensitisation is removal of moisture from the emulsion , moist forming gas mixture will result in poor hypersensitisation.

Last edited by Ian Robinson; 15-05-2008 at 10:03 PM.
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Old 16-05-2008, 01:11 PM
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A few more comments about decanting high-pressure gas into a low pressure cylinder - as Monte points out, if you get it wrong, you may not be around any longer. Or rather, you may be all over the place. A 20 L cylinder at 200 psi will have 260 L of gas in it, or about 10 moles at 20 C. The (pressure) energy is then about 36 MJ, or about the same as in a litre of petrol or a few kg of high explosives. It goes off even better with some O2 added, so everything has to be flushed and O2 free.

However it is possible.

A LPG cylinder is tested to 3.3 MPa (32 atm - that's atmosphere's, not amateur telescope makers!) and has a burst pressure of about double that. The max safe working pressure is about 1/2 that - about 13 atm or 200 psi. Obviously you also need to take into account the temperature effects - as the temp rises, the pressure will too.

So if you limit the gas pressure to something safe, then there should be no problems. Except maybe due to hydrogen embrittlement of the steel cylinder - which is why H2 tanks are lined to protect the steel (and stop leakage) or N2 or something else is added. Transporting H2 by pipeline is a problem due to embrittlement and leakage, but adding 10 - 20% methane stops the embrittlement and leakage - the larger molecules plug up the pores in the metal and also seal the metal crystal lattice. Maybe as a chemist you know all this?

Of course being a chemist you should also know how to make H2 - zinc and HCl - use old die-cast metal bits and pool grade HCl. Or Al and NaOH, but be careful as the Al + NaOH starts off slow due to the Al2O3 coating on the Al but as it dissolves aways and also heats up, the reactions can get much faster.

If you want pure H2, pass the gas you make through water to wash it, and then dry the gas by passing it through a cold trap - pass the gas through a vessel under ice or dry ice. Or pass it through silica gel. Even better, through ice then gel. If you want to store home-made H2, use a fridge compressor and pump it in a LPG cylinder. But you need to pas the gas through another cold trap - dry ice and ether or liquid N2 - to catch the oil vapours from the pump.
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Old 16-05-2008, 01:17 PM
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Hyper tanks and gases

We used BOC for our stuff in the good ol' days. Now, that brings back memories......
The ASV had a very active Astrophotography section back in the 80' early 90's ( I was Director) and many of the members had and used Hyper tanks.
Unfortunately over the years mine has disappeared, but there still may be one or two available from the old guard in the ASV. Steve Pattie's name comes to mind.
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Old 16-05-2008, 01:57 PM
Ian Robinson
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Quote:
Originally Posted by Suzy_A View Post
A few more comments about decanting high-pressure gas into a low pressure cylinder - as Monte points out, if you get it wrong, you may not be around any longer. Or rather, you may be all over the place. A 20 L cylinder at 200 psi will have 260 L of gas in it, or about 10 moles at 20 C. The (pressure) energy is then about 36 MJ, or about the same as in a litre of petrol or a few kg of high explosives. It goes off even better with some O2 added, so everything has to be flushed and O2 free.

However it is possible.

A LPG cylinder is tested to 3.3 MPa (32 atm - that's atmosphere's, not amateur telescope makers!) and has a burst pressure of about double that. The max safe working pressure is about 1/2 that - about 13 atm or 200 psi. Obviously you also need to take into account the temperature effects - as the temp rises, the pressure will too.

So if you limit the gas pressure to something safe, then there should be no problems. Except maybe due to hydrogen embrittlement of the steel cylinder - which is why H2 tanks are lined to protect the steel (and stop leakage) or N2 or something else is added. Transporting H2 by pipeline is a problem due to embrittlement and leakage, but adding 10 - 20% methane stops the embrittlement and leakage - the larger molecules plug up the pores in the metal and also seal the metal crystal lattice. Maybe as a chemist you know all this?

Of course being a chemist you should also know how to make H2 - zinc and HCl - use old die-cast metal bits and pool grade HCl. Or Al and NaOH, but be careful as the Al + NaOH starts off slow due to the Al2O3 coating on the Al but as it dissolves aways and also heats up, the reactions can get much faster.

If you want pure H2, pass the gas you make through water to wash it, and then dry the gas by passing it through a cold trap - pass the gas through a vessel under ice or dry ice. Or pass it through silica gel. Even better, through ice then gel. If you want to store home-made H2, use a fridge compressor and pump it in a LPG cylinder. But you need to pas the gas through another cold trap - dry ice and ether or liquid N2 - to catch the oil vapours from the pump.

I am aware of hydrogen embrittment of steel , there is another mechanism that you perhaps have not heard of , where hydrogen enters the steel and diffuses to voids and fills them with very high pressure hydrogen which causes the steel to rupture along grain boundaries and can lead to catastrophic failure.
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Old 16-05-2008, 08:12 PM
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Joe Cauchi - Our club vice president is still using film. He uses a colour negative film that is not hypered and he gets good results on his 16".

I will ask him next time I see him what film he is using.

Maybe you don't need to bugger around with all that stuff after all.
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Old 16-05-2008, 08:16 PM
Ian Robinson
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Quote:
Originally Posted by montewilson View Post
Joe Cauchi - Our club vice president is still using film. He uses a colour negative film that is not hypered and he gets good results on his 16".

I will ask him next time I see him what film he is using.

Maybe you don't need to bugger around with all that stuff after all.
Nice to know there are still a few dinosaurs like me about.
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Old 17-05-2008, 02:47 PM
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Quote:
Originally Posted by montewilson View Post
Joe Cauchi - Our club vice president is still using film. He uses a colour negative film that is not hypered and he gets good results on his 16".

I will ask him next time I see him what film he is using.

Maybe you don't need to bugger around with all that stuff after all.
I think you are correct, I seem to remember reading on the APML a few years ago that a lot of the newer films (Neg and Reversal) don't respond to hypering.... and don't really need it.
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Old 17-05-2008, 03:08 PM
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I think you are correct, I seem to remember reading on the APML a few years ago that a lot of the newer films (Neg and Reversal) don't respond to hypering.... and don't really need it.
That's interesting .... Maybe my old hypering chamber can stay in retirement if that is the case.

I believe Lumicon still sell hypered film though (npt sure about that , there was someone in Australia who was running a commercial operation for while offering hypered films too for a while).

Last edited by Ian Robinson; 17-05-2008 at 03:35 PM.
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Old 17-05-2008, 03:15 PM
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Hypering film

I'm a little surprised to hear that modern film doesn't respond to hypering.
The hydrogen gas displaces the larger oxygen and water molecules in the gel and suppresses the reprocity failure. I know some films move their colour responce but I'd think all films would improve to some degree.
You could also consider a Cold camera using frozen C02; more fiddly but very usable.
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Old 17-05-2008, 03:33 PM
Ian Robinson
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I'm a little surprised to hear that modern film doesn't respond to hypering.
The hydrogen gas displaces the larger oxygen and water molecules in the gel and suppresses the reprocity failure. I know some films move their colour responce but I'd think all films would improve to some degree.
You could also consider a Cold camera using frozen C02; more fiddly but very usable.
Cold cameras are hard to find these days .... I think I saw one for sale on Ebay last year and it was snapped up straight away by someone.

I think it is more likely that modern films (B&W , colour and slide) can benefit from hypersentisation , but with the demise and buyout of Lumicon , and them having a patent on the process , it was something that fell out vogue.

Here's a link that discusses hypering for anyone who might be considering doing it and gives info on various films. http://home.nethere.net/mpd/FilmTest...estSummary.htm
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Old 17-05-2008, 03:39 PM
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I could be wrong, It has been some time since I was on the APML mailing-list.
Might be worth searching the Archives for your film of choice to get opinions.
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