Kodak RA4 RA/RT developer keeping qualities

[Bob-D659]

RA4 developer is a bit fussy for keeping qualities according to Kodak, but a print from the Feb 2011 test bottle looks exactly the same as one from a fresh mix from yesterday. The tint of the developer is close to being the same as well. I'm using Kodak Supra Endura paper and processing at room temp, without adding a starter to the developer when using steam distilled water to mix the concentrates and storing the mix in a 2 liter soda bottle.

From a fresh mix I can get two to four 8x10 prints or equivalents in 4x5 test prints from 70 ml of working solution used three or more times in an 8x10 drum at room temp in a span of an hour or two. Well the year old stuff can do one print in a drum that is visually identical to the previous test prints done over the last year. Three months ago two prints done an hour apart in the same "cup of soup" were visually the same, but not today. The second one is lacking the "sparkle" of the first one, so the developer is on it's way out and is now really a one shot developer.

It does keep much longer than Kodak's conservative 6-8 weeks, but a year is pushing it. I'm not complaining, that's for sure, as always YMMV.

 

[Photo Engineer]

Bob;

It depends on container. I have kept mixed RA-RT developer replenisher in half full bottles and 1/4th full bottles for up to 6 months, but I do use Nitrogen to exclude air as much as possible. It keeps far better than Kodak suggests. When it is going bad, it starts to look like coffee. Dark strong coffee.

PE

 

[kb3lms]

PE, where do you get the nitrogen? How do you have that set up?

I have a few things to print RA-4 but have been holding off mixing up a liter of chems since I wouldn't use them to capacity in the near future due to the other things I've been working at. I would agree that it does last pretty long, though.

Some folks talk about using butane or gas from those "dust off" cans. Does those alternatives work as well as nitrogen?

-- Jason

 

[fotch]

You will get a big bang for your buck with Butane!

A welding supply vendor is where I get tank, valve, regulator, and probably a nearly lifetime supply of gas.

 

[waynecrider]

For the heck of it you can always check Craigslist. Also, some wine stores carry canisters of inert gas to fill half empty wine bottles; A little more pricey tho, but compared to a tank and regulator, less out of the pocket and easily store-able.

 

[DREW WILEY]

I always mix it per print or per daily work session, so am more concerned about the keeping qualitites of opened concentrates after several months of inactivity. I generally figure it's not worth the risk, so buy new concentrates each season, though I might test strip some the older stuff first. RA/RT has been very reliable for
quality however, so it's nice to stay with it. I simply use it one-shot in drums, so performance is always uncompromised.

 

[Bob-D659]

I have a nitrogen cylinder in the shop and a smaller 250 psi tank is the darkroom, it works really well as a super duster with adjustable pressure, and for purging the factory concentrate bottles.

I just did this test to see how long the stuff really kept. I normally just mix up 2 liters at a time and use it up. The test bottles were the last from a set of concentrates that had been opened for months, and there is about a liter left.

Kodak's keeping times must be for absolute worst case storage conditions.

I once left some on the counter open for a few days, dark strong coffee looking is an understatement, more like the colour of roofing tar.

 

[fotch]

Bob, something I am interested to know about is your smaller 250 psi tank. Any info would be appreciated. TY

 

[Photo Engineer]

Well, roofing tar is accurate when it is really bad!

Nitrogen comes in several sized tanks at various pressures. You can buy the tank outright or rent one and you will also need a pressure reduction valve. The valve is the most expensive part I think. I have not priced them out in years. You can get this all at a welding supply shop. A refill last I knew was about $25 and it lasts for years. My full tank has lasted nearly 10 years.

PE

 

[Bob-D659]

The 250 psi tank is just a steel tank rated at 300 psi working pressure, with an old oxygen regulator and a few pipe fittings to adapt it so I have a fill valve and I can adjust the delivery pressure. I refill it from the larger high pressure cylinder to 250 psi.

Single stage regulators start at approx $50-75 for an inert gas one for a mig welder. Add a couple of hundred or more for a good quality two stage one, which you don't need.

In Canada you can't buy the large K cylinders, just the smaller two standard sizes.

 

[DREW WILEY]

$50 regulator on 250 PSI tank ... are you nuts? Here we classify that as a pipe bomb.

 

[Bob-D659]

I said you can buy one, I use a small Victor oxygen regulator on the 250 psi tank and have a few used nice chromed L-TEC two stage ones in my shop for nitrogen and oxygen. And those $50 regulators are rated for 2200psi for oxygen and can be used with nitrogen or argon, just change the bottle fitting.

http://www.princessauto.com/pal/product/8082471/MIG/Wire-Feeds/Argon/CO2-Regulator $80 not on sale in Canada

In the US,

http://www.harborfreight.com/regulator-gauge-94841.html Inert gas on sale for $34

You don't need a $400+ chromed lab/medical grade two stage high flow rate regulator for nitrogen in a shop.


Dead Link Removed Oxygen as well, same price.

If they start to leak, and every one of them will no matter the price or maker, just replace them as it's cheaper than getting a brand name one rebuilt. And they will all leak eventually, the bigger problem is most welding shops in the US won't rebuild any of them.

 

[fotch]

They won't rebuild them because of the liability however, if you bring them in to adapt or change the fitting, no problems. Never had one that needed to be rebuilt but then again, they would not of got a lot of use from me. One used commercially may be different.

 

[markbarendt]

Another option for storage are recycled wine box bladders. I mix 5-liters at a time and there is no introduced air for the life of the batch. Works great.

 

[darkroom_rookie]

I just use medium, smaller and even smaller brown glass bottles with some plastic bag material below the cap. A batch mixed early November last year worked fine this week, replenished as per Kodak's instructions.

 

[hrst]

According to my experience -- even two years without any problem! Stored in a PET bottle with air squeezed out at room temperature (23 deg C).

I have had the opened concentrate go bad, but never the working solution, which is quite funny.

 

[Photo Engineer]

I would have to agree!

PE

 

[fotch]

According to my experience -- even two years without any problem! Stored in a PET bottle with air squeezed out at room temperature (23 deg C).

I have had the opened concentrate go bad, but never the working solution, which is quite funny.

Could it be due to oxygen in the concentrate bottle after opening?

 

[Photo Engineer]

IMHO, yes.

PE

 

[fotch]

IMHO, yes.

PE

If one were to use Nitrogen, in the concentrate, after opening, it would last longer?

 

[Bob-D659]

I purge my concentrate bottles with nitrogen after I remove enough to mix one or two liters and they seem to last at least 8 months or so after opening. I had one croak, but there was only enough left in it for a liter of developer and it had been opened and purged multiple times. The part B turned an ugly black, guess I didn't do a good job on purging that little bottle. This was a set packaged in 2007, week 29 and the source for the test bottle mentioned above. It would have been opened in mid 2009. I forgot to record that date.

Factory sealed they are ok for two years according to Kodak, pretty sure they keep at least three years or maybe longer.

I had a set packaged in 2008, the part B was still good, but the part C bottle had been jammed into a nail in the back of the storage cabinet at some point in time and most of that bottle was in the bottom of the zip lock bag I keep each set in. That set was disposed of the other day. The nail has been neutered as well.

The part A of that set was slightly darker than the newer sets I have, so it seems to darken with age, but I don't know if that has any bearing on the capacity or what.

 

[hoffy]

I don't know if there are differences, but I have been recently using a Tetenal RA4 kit that I opened in May last. While I had to throw out the working solution that I still had mixed from back then (including the bottle that had the dev in it - it had gone black and flakey), the concentrate for both the dev and the blix appears to be OK.

 

[Photo Engineer]

Yes. But not forever. The developing agent part is not packed under N2, it is packed under SO2!

PE