Kodak RA/RT Usage Advice (Replenishment)

[Bumba]

Okay I think I have my suspect. I cleaned off the bulb terminals with a bit of vinegar and a scouring pad and they looked good. Got it all set back up and my density got worse haha. The bulb came with the enlarger and I had the enlarger a few years ago so I think I'm going to try a new one and see how that goes

 

[peoplemerge]

@Bumba can you provide a bit more info on your enlarger and timer?

Most of us set up our darkrooms back a long time ago have gotten used to a few critical facts:
1. In general, use a dichroic diffusion enlarger (if you are not, then let us know and we'll have that conversation)
2. Use a voltage regulator in the power source for your dichroic enlarger
3. In general, use a digital timer that allows you to adjust time to the precision of at least 1/10 sec when you are printing for 9 sec. I've gone a bit overboard with my setup a metrolux that measures light output instead of time, which is really solving the light out of "cold light" enlargers, not dichros.

 

[peoplemerge]

Read most of this thread a points to ponder

wine bags ftw
I am totally in agreement with @mnemosyne that wine bags are the best "life hack" for darkroom. My last order, I bought a set of 50. They're specifically for preserving ... wine ... which can't be oxidized after decades in storage. What can possibly be better? Glass wine bottles, you say? That is true, it is also stored in glass. The great thing about the bags is you can pour out a little bit at a time without "opening a bottle" that you have to finish soon later. The downside is it's a pain to pour chemicals back in. For chemicals I use pretty often and discard after a few weeks, it's glass bottles, but I'm thinking of going back to the plastic accordion bottles for those short term use ones.

blix
There's been many debates here about using blix vs separate steps for bleach and fixer. I go back to this one https://www.photrio.com/forum/threads/just-how-bad-is-blix-vs-bleach-fixer.53336/
The gist is: you can order "Ektacolor Blix Part B" which is only the bleach, and use most any fixer (I use Flexicolor which is a film bleach for most b/w, c41 film, and ra4, and alt processes) (Edit: maybe don't do this, I'm re-reading my sources here on Photrio, and I may have gotten it wrong). Apparently if you want to save money, the bleach is more durable than the fix, so by separating them you get more life out of the bleach, and buy fix in bigger qtys to reuse in b/w if you are into that. To mix separate baths here's the rule of thumb: a 4L blix kit will provide you 3L bleach and 3L fix.

 

[koraks]

There's been many debates here about using blix vs separate steps for bleach and fixer.

Sure, but that applies mostly to film. For paper, blix is the standard solution which has been tried and tested. Additionally, replenished blix goes quite a long way and is therefore very cost effective. I personally see no significant benefit in separating bleach and fix steps for RA4 unless techniques such as bleach bypass are necessary, but that's an exception. For normal RA4 printing, a blix is qualitatively excellent, cost-effective and convenient.

 

[Bumba]

@Bumba
1. In general, use a dichroic diffusion enlarger (if you are not, then let us know and we'll have that conversation)
2. Use a voltage regulator in the power source for your dichroic enlarger
3. In general, use a digital timer that allows you to adjust time to the precision of at least 1/10 sec when you are printing for 9 sec.

Hi Peoplemerge. I'll do my best to answer these questions but I'm not very savvy with electronics

My enlarger is a Durst M370 colour enlarger and it has a box inside that diffuses the light. Not sure if it's dichroic though. It's connected to a Durst TRA transformer then into an electro magnetic timer (Durst TIM 60). I had a conversation with someone about using a voltage stabilizer also but I think that'll be a last resort for me. A google search said that the voltage in the UK is 230v +6% or -10%.

It takes a 12v bulb so I guess the transformer steps it down to that.

In the end I went for the wine bags but went for the clear ones over the aluminium coated ones just so I could see all the air bubbles and remove them. So far so good with it. I keep 3l of mixed chemicals in those each and another 2l each separate in glass bottles for long term storage.

Thanks for the help. I received a new bulb today so I'll test that today and return with some answers.

 

[koraks]

Durst TIM 60

Is the timer mechanism in that one mechanical or electronic? Looks like a mechanical timer and if that's the case, I wouldn't trust it for color work with short exposures.

 

[Bumba]

Is the timer mechanism in that one mechanical or electronic? Looks like a mechanical timer and if that's the case, I wouldn't trust it for color work with short exposures.

Im pretty sure it's mechanical. It makes a whirring noise as it works

 

[koraks]

Right. It's probably decades old and the timer mechanism may have dirt in it or have worn, making it inaccurate. Have you tried establishing its accuracy? With a little creativity, you could work out a way to do this.
Or, easier: try a different timer. A reliable one.

 

[Bumba]

Right. It's probably decades old and the timer mechanism may have dirt in it or have worn, making it inaccurate. Have you tried establishing its accuracy? With a little creativity, you could work out a way to do this.
Or, easier: try a different timer. A reliable one.

Haha it's defo a little old but seems fairly reliable to me. I'll do a few tests on it and test it's accuracy. I'll report back

 

[Bumba]

Just tested my timer at 12s. I recorded 6 exposures then in a video editor trimmed to clips to when the light was on. Every exposure was almost identical at 12.1s or so. Not much in it to make a difference.

Since cleaning the bulb terminals, the filtration has become more red by 5-10 units. Going to try my new one out.

 

[Bumba]

Just tried out the new bulb and it's looking pretty good but I'll have to see after a few sessions.

These are my observations at the same settings
Old bulb - test strip looked quite red and was overly dense
New bulb - test strip looked more normal with lower but better density. Exposures look more stable at first glance over time too. No dimming over time.

The ceramic filament holder part also came away from the reflector on the old bulb and was a bit blackened around that area. Still worked alright tbh before I cleaned off the corrosion but not very stable. I think it would have been wise to just buy a new bulb when I got the enlarger (word of warning to people in the future)

 

[koraks]

Fingers crossed!

 

[peoplemerge]

My enlarger is a Durst M370 colour enlarger and it has a box inside that diffuses the light. Not sure if it's dichroic though.

There are really two enlargers out there, condensers which have a slot for contrast and color, and diffusion dichros which have color knobs. Way back in the day there were a couple diffusion non-dichro without knobs but not many are out there. Googling the M370, yes I see color knobs / wheels; you have a dichro.

It's connected to a Durst TRA transformer then into an electro magnetic timer (Durst TIM 60). I had a conversation with someone about using a voltage stabilizer also but I think that'll be a last resort for me. A google search said that the voltage in the UK is 230v +6% or -10%.

+6% to -10% change in voltage is more than enough change in current to explain your color shifts. I'm not an expert, but I'd hope to see you under 1%. A fridge or washing machine in your house turning on will affect the time required for equivalent density; on the same electrical circuit (ie circuitbreaker at your box) is deadly. It's pretty standard practice to use a voltage stabilizer when you set up for color work; I would expect a used enlarger to come with one. Some may have had them built in for all I know. Some timers do, notably the Chromegatrol (they are for Omega enlargers).

In the end I went for the wine bags but went for the clear ones over the aluminium coated ones just so I could see all the air bubbles and remove them. So far so good with it. I keep 3l of mixed chemicals in those each and another 2l each separate in glass bottles for long term storage.

Nice! Yes, I'm using the same clear ones. Though I do the opposite. Glass bottles for short term storage since it's ok for some air to get in, bags for the long term.

Fingers crossed!

Yes. Ideally you are set with a new bulb. The diffusion enlargers I've had have all used halogen bulbs, they either work, or they don't.

 

[peoplemerge]

Sure, but that applies mostly to film. For paper, blix is the standard solution which has been tried and tested. Additionally, replenished blix goes quite a long way and is therefore very cost effective. I personally see no significant benefit in separating bleach and fix steps for RA4 unless techniques such as bleach bypass are necessary, but that's an exception. For normal RA4 printing, a blix is qualitatively excellent, cost-effective and convenient.

I agree, you are totally correct it does mostly apply to film.
I thought the bleach didn't need to be replenished at the same as fix, but it turns out that's not true (capacity). However, they keep longer when kept separate (longevity), according to Bleach not Blix RA-4.

I'm glad I reread this: it means I might as well keep storing them separately, and keep only a working solution mixed as a blix for however much I need to use. I think I'm going to take back what I said about fixers being interchangeable to avoid disseminating potentially false info.

 

[koraks]

I haven't had Blix go bad on me, at least not the working solution which is replenished anyway. It will die eventually of course without replenishment. And single part Blix concentrate doesn't keep very well in partially full bottles with oxygen present. In full bottles it keeps for at least 18 months in my experience.

 

[koraks]

Googling the M370, yes I see color knobs / wheels; you have a dichro.

It's a dichroic head alright. I've used one of those for color work for a year or so. With the bulb that came with it which must have been 15 years old at least when I got it. Saw some pretty heavy use in my darkroom as well. I never noticed any problems with it in terms of stability or otherwise. Great little unit if you only need to do 35mm.

 

[Bumba]

Just out of curiousity, would the transformer on the Durst also stabilise the voltage?

 

[koraks]

I never opened it up, but it didn't look like there was much in the box besides a transformer. If you really want to know, see if you can open it and snap and few pics of the inside; that'll most likely clarify it.

 

[Bumba]

Not too problematic because 2 of the latches are broke on it so I've only got the top taped down.

 

[koraks]

There's no voltage stabilization in there.

 

[peoplemerge]

I'd definitely recommend voltage stabilization.
I'd also definitely recommend a darkroom timer that can do 0-9sec to the precision of 0.1 sec and 0-99 sec to the precision of 1 sec.
I don't remember if you mentioned whether or not you any, but if you don't have them, get some color printing viewing filters.

Your color darkroom setup right now is almost there. Get that ^ solved and you'll be printing "fo realz": with maximum repeatability and minimal frustration!

I took a color darkroom class at a place that is recently closed and it's really not hard to get stunning results. You don't need a class. They taught me to get the density right on (exposure) then adjust color. Then adjust density if needed, then color.

I also learned to speed this up using the color wheel and viewing filters to add a few % color.
"
If you want your print to be more: Subtract this filtration:
Magenta Magenta -1% for 1pt m
Yellow Yellow -1% for 5pt y
Red Magenta and Yellow -6% for 5pt y&m

If you want your print to be more: ADD this filtration:
Green Magenta +1% for 1pt m
"...etc

This is why you want your timer to be good for .1 sec: that way when you adjust your colors, you can adjust the time accordingly and get closer to the correct density.

 

[koraks]

This is why you want your timer to be good for .1 sec: that way when you adjust your colors, you can adjust the time accordingly and get closer to the correct density.

Frankly, within about 8 or 10cc filtration change I find the overall difference in density too small to bother about.

 

[Bumba]

Thanks for the help guys. I'm starting with small steps for now. If I get problems with consistency I'll look into a voltage stabilizer but when I looked they were around £100 and not very easy to come across. The next time you hear from me I'll have my first print done and dusted (hopefully haha).

P.s. I do have some Kodak filters but I think the units are different to Durst so don't use them too much. I think I looked up the conversion. 1.5 Kodak units = 1 Durst unit if I remember correctly

 

[Bumba]

I'm back and unfortunately with no finished print. I think you guys were correct about the voltage stabilizer. Next to my enlarger is the boiler for the house. Everything was going fairly well but before I made my last strip the boiler turned off. Made my test strip and the density was a lot more than previous. I'm guessing that the boiler and enlarger are on the same line or something.

I've looked online for voltage stabilizers but not coming up with anything. Could anyone recommend anything to try or any old darkroom ones that I could pick up second hand?

Also could I not just turn off the boiler every time I make an exposure and get some sort of consistency?

Thanks and this is so frustrating. I'm glad I'm a patient person or my enlarger may have met an untimely end

 

[koraks]

Get a 12v smps with a power rating of at least 150W. Your enlarger bulb will be just as happy with DC as it is with AC.
In a pinch a computer power supply may do fine.
The only issue is that there can be some filter capacitance on the output of the power supply which delays the bulb turnoff for a fraction of a second so exposure times of less than, say, 6 seconds or so may be slightly longer. Depends on the power supply used though. I don't think it'll be an issue with most units.