Using RA-4 chemistry

[filip0502]

First of all, I'm sorry. I know there are a bunch of topics about this, but I just wanna be sure that I got it right.
I wanna try color printing, and I've been a little confused as to how RA-4 chemistry is used.
I bought an Adox kit, and the datasheet says that a 2.5-liter working solution can develop 115 18 x 24 cm papers. So if I mix 500 ml, I can use it for 23 papers, right?
My biggest concern is, when I pour in the developer, do I pour what I need to cover the print and then put it back in the bottle with the unused working solution, or do I have to discard it?
I'm asking this because I saw videos of people printing RA-4, and they would measure a small quantity of chemistry (like 60 ml, because they are using a drum), and then they would throw it away.
Thanks in advance for any advice!

 

[synhare]

From my understanding most people use rotary processing (JOBO) and the chemistry is one-shot, meaning you discard it after using on a single print. The idea is that the small amount of chemistry will slosh around and cover the print as the development drum is rotated.

 

[koraks]

There are many ways to skin this cat. I've written a blog about it, but it's not exhaustive: https://tinker.koraks.nl/photograph...ta-using-color-c41-and-ra4-chemistry-at-home/
Also, it may not fit your particular use case, although what's written there is still mostly (I think, I'd have to check) valid and open for consideration.

do I pour what I need to cover the print and then put it back in the bottle with the unused working solution, or do I have to discard it?

Both approaches are possible; they both have their pros & cons.

One obvious consideration is that 500ml/23=ca. 22ml for a print and you'll be hard-pressed to manage to develop a 18x24cm print with 22ml of developer. So obviously you have to use a larger volume, and that means that you'll have to engage in some kind of re-use scenario. In a tray, you'll generally need upwards of 100ml of liquid to reliably & conveniently cover a print this size. This means that you either under-utilize the developer if you discard it after one use, or you re-use it in which case the activity of the developer will vary and shift. For color prints this is not necessarily a problem right away, but at some point it becomes visible as color shifts and especially failure to reach dmax (pure black), with the paper developing into a deep blue instead of black (given sufficient exposure).

In practice you could use e.g. 500ml of developer in a tray and just keep using it until it has become insufficiently active. You can extend development time or increase temperature at the 'tail end' of the developer's lifetime to squeeze some more life out of it, but consistency of your prints may/will suffer. How much of a problem this is...hard to tell; you'd have to try for yourself. With drums, a similar approach can be used where you put the used developer (e.g. 60ml) back with the rest (e.g. 500ml) and then take another 60ml from that same 500ml volume for the next print, and so on until the developer becomes too slow to get the job done.

Technically the best and IMO most practical approach is to replenish both the developer and blix, but sadly, the ADOX chemistry does not come as a replenisher, so you're left with the only option to reuse until a certain point and then discard.

 

[filip0502]

There are many ways to skin this cat. I've written a blog about it, but it's not exhaustive: https://tinker.koraks.nl/photograph...ta-using-color-c41-and-ra4-chemistry-at-home/
Also, it may not fit your particular use case, although what's written there is still mostly (I think, I'd have to check) valid and open for consideration.


Both approaches are possible; they both have their pros & cons.

One obvious consideration is that 500ml/23=ca. 22ml for a print and you'll be hard-pressed to manage to develop a 18x24cm print with 22ml of developer. So obviously you have to use a larger volume, and that means that you'll have to engage in some kind of re-use scenario. In a tray, you'll generally need upwards of 100ml of liquid to reliably & conveniently cover a print this size. This means that you either under-utilize the developer if you discard it after one use, or you re-use it in which case the activity of the developer will vary and shift. For color prints this is not necessarily a problem right away, but at some point it becomes visible as color shifts and especially failure to reach dmax (pure black), with the paper developing into a deep blue instead of black (given sufficient exposure).

In practice you could use e.g. 500ml of developer in a tray and just keep using it until it has become insufficiently active. You can extend development time or increase temperature at the 'tail end' of the developer's lifetime to squeeze some more life out of it, but consistency of your prints may/will suffer. How much of a problem this is...hard to tell; you'd have to try for yourself. With drums, a similar approach can be used where you put the used developer (e.g. 60ml) back with the rest (e.g. 500ml) and then take another 60ml from that same 500ml volume for the next print, and so on until the developer becomes too slow to get the job done.

Technically the best and IMO most practical approach is to replenish both the developer and blix, but sadly, the ADOX chemistry does not come as a replenisher, so you're left with the only option to reuse until a certain point and then discard.

With drums, a similar approach can be used where you put the used developer (e.g. 60ml) back with the rest (e.g. 500ml) and then take another 60ml from that same 500ml volume for the next print, and so on until the developer becomes too slow to get the job done.

That's what I was going for. I plan on developing with a drum (actually with a film tank until I get a proper drum), and this seems the best option to me without doing replenishing. I'm just starting out, so I'm not that worried about getting the most out of the kit.
If I continue doing RA-4, I'll look into a kit that can be replenished to get the most out of it.

 

[koraks]

Sounds good; be sure to post back with your experiences so others can benefit! And I'm sure there will be some more replies with additional insights and advice.