On 07/10/2013 03:10 AM, C.Breukel@xxxxxxx wrote:
Thanks for the feedback guys, Jean-David: I too found that Wiki link, so
I too assumed it to be decahydrate.
The reason for asking is that I am weighting out some chemistry for a
friend to mix FX-37. He was inspired by another friend who uses it all
the time. Much to my surprise when I could finally get in touch with the
“source” (he was on holiday) he replied that the Borax he uses : de
borax is CAS: 1330-43-4. M=201,22g/mol
**
So that’s the anhydrous form, and there is almost a factor 2 weight
difference (381.38/201.22 * 2.5 gram = 4.7 gram Borax per litre) so if
you guys are right and it should be de decahydrate form, my friend is
using almost twice as much Borax as intended in the original formula.
How harmful is that, i.e. will it make the FX-37 faster or more
contrasty developer ?
First of all, not that I am not a photo-chemist.
I remember reading about the various formulae for black and white
photographic developers where I believe it was Kenneth Mees who said
that with the plethora of chemical formulae available that there were an
extremely large number of ways by which identical results may be obtained.
So I would not worry much about it. Your friend will have to calibrate
the developer anyway to suit the film, light meter, shutter(s), aperture
settings, enlarger characteristics (if enlarging), etc., etc.
So while I expect that using dessicated borax (if it stays dessicated
until you weigh it out) would get you a slightly more contrasty
developer, that your friend, after calibrating it, would just use a
slightly shorter development time to get the contrast he wants.
If the dessicated borax was kept around long enough here in New Jersey,
the stuff would become partially hydrated from the high relative
humidity we have. Here in USA, it is probably difficult to get borax in
other than the decahydrated form.
I think the FX formulae are American, right? If so, I assume the
decahydrate is meant. If it is English, they may mean dessicated.
When all is said and done, more is said than done. Mix it up with
whatever form of borax you have. Then calibrate it. I used to play
around with developers a lot. Now I use mostly Xtol developer 1+1. When
I cannot get that anymore, I will go back to mixing D-76-d.
FYI FX-37:
Sodium sulfite, 60.0 g
Hydroquinone, 5.0 g
Sodium carbonate, anhydrous, 5.0 g
Phenidone, 0.5 g
Borax, 2.5 g
Potassium bromide, 0.5 g
Benzotriazole, 1% solution, 5.0 ml
