RA-4 formula photo quality.

Has anyone tried the RA-4 formula found here?:
http://www.bonavolta.ch/hobby/en/pho..._chemicals.htm . What were the
results like?Do the photos look similar to ones processed in RA-4 chemistry
by Fuji or Kodak? Do you need to use distilled water for mixing?

Thanks in advance,
Rob.

In article ,
"Rob" writes:

Has anyone tried the RA-4 formula found here?:
http://www.bonavolta.ch/hobby/en/pho..._chemicals.htm . What were the
results like?Do the photos look similar to ones processed in RA-4 chemistry
by Fuji or Kodak? Do you need to use distilled water for mixing?

I've used it, but I've not done any critical side-by-side comparison of it
to commercial RA-4 kits. Considered by themselves, the results seem fine
when I've used Kodak, Fuji, or Agfa paper. (I get a slight yellow cast in
white areas when I use Konica paper I bought off of eBay, but I'm not sure
if that's a problem with that formula and Konica paper generally or if
it's an indication that the paper's a bit long in the tooth. I have no
problems with the paper when processed with commercial chemicals, though.)
I still consider myself a beginner at color printing, and somebody more
discerning than I might find this formula unsatisfactory, but for the
moment I'm happy with it. I've always used distilled water with this
formula, so I don't know if tap water would be a problem.

I know of another Web-accessible RA4-compatible formula:

http://www.people.fas.harvard.edu/~k...technical.html

(This page actually includes a link to a page with two older formulas by
the same author, which in turn contains a link to another page with a
formula that's probably best not to use for reasons described on its
page.) This formula uses several ingredients that I don't have on hand and
that aren't carried by the usual raw photochemistry suppliers, so I've not
tried it. I may give it a try one of these days if/when I find it
convenient to get the missing ingredients. I hear from reliable sources
(namely, a retired Kodak chemist who posts on APUG, among other places)
that this formula is much closer to Kodak's RA-4 formula than the one to
which you linked.

--
Rod Smith,
http://www.rodsbooks.com
Author of books on Linux, FreeBSD, and networking

On Thu, 28 Dec 2006 18:28:07 GMT, "Rob" wrote:

Has anyone tried the RA-4 formula found here?:
http://www.bonavolta.ch/hobby/en/pho..._chemicals.htm . What were the
results like?Do the photos look similar to ones processed in RA-4 chemistry
by Fuji or Kodak? Do you need to use distilled water for mixing?

Thanks in advance,
Rob.


Rob, I have looked at the formula given in the URL and at first glance
I would say that it is okay except that Potassium Chloride should be
used instead of Sodium chloride.

I provided the formual below back in a 1993 news group post and I
have used this for a number of years.

CD4 is more active than CD3 so you only need about half as much CD4
for a given prescribed amount of CD3.

Similarly with CD3 you will notice that you need more Potassium
Carbonate and a little Potassium Hydroxide.

With RA4 papers, if there is insufficient CD4 or the alkalinity is too
low then you will not get good blacks, instead the black will be
bluish black because the bottom yellow forming layer will not be
completely developed.

You should not need distilled water for the developer unless your
water supply has excess chlorine or other contaminents.


RA4 Developer as publised in 1993:

Sodium Sulphite [Anhdrus]......................1.5grams
Triethanolamine ......................................10ml
Potassim Chloride ....................................1.5gm
Potassium Carbonate...............................35gm
CD-4................................................. ........2.5gm
Water to .................................................. .1.0litres
pH 10.1-10.3



Process as per Kodak times [45sec] and temperature [35 degrees C]
[note CD-4 is "two point five grams" you don't need much,
alternatively use 5gm of CD-3]

To get better wetting you can add say 20ml of di-ethylene glycol to
the above developer.

Do you want the formula for the combined bleach - fixer?

Good luck ......... Frank Webb

In article ,
(Frank Webb) writes:

CD4 is more active than CD3 so you only need about half as much CD4
for a given prescribed amount of CD3.
....
RA4 Developer as publised in 1993:

Sodium Sulphite [Anhdrus]......................1.5grams
Triethanolamine ......................................10ml
Potassim Chloride ....................................1.5gm
Potassium Carbonate...............................35gm
CD-4................................................. ........2.5gm
Water to .................................................. .1.0litres
pH 10.1-10.3

A retired photochemist has posted on APUG (and probably elsewhere) that
using CD-4 in an RA-4 developer is inadvisable. Apparently there are image
stability issues; prints developed in such a developer are likely to fade
more quickly than prints developed in a developer that uses CD-3. (I don't
have exact time frames on this, though.) Therefore, I personally wouldn't
use this formula for anything I'd want to last.

--
Rod Smith,
http://www.rodsbooks.com
Author of books on Linux, FreeBSD, and networking