Newbie question about chemistry
Richard Knoppow
"the letter K" <we...@werp.com> wrote in message
news:20gisv8d2rdag9ido...@4ax.com...
> I am familiar with the basics of processing a roll of B&W
film, i.e.
> developing the negatives and making prints. HOWEVER, I
have never
> mixed chemistry. In the near future I plan to begin doing
so.
>
> I've done a lot of searching on the internet and reading
various books
> in the library, but so far I've only come across rather
non-specific
> descriptions of the process. Typically, such articles
will say "mix
> the chemistry according to the manufacturer's
instructions." However,
> I've examined a packet of D-76 powdered developer and
didn't see
> anything that resembled specific instructions.
>
> My highly tentative understanding of mixing, say, D-76
developer is as
> follows:
>
> * If I have a "makes one gallon" packet of D-76 powdered
chemical, I
> am to mix that into 1 gallon of water and store the result
in a
> suitable container. I can then use that mixed solution
full-strength,
> or diluted at a 1:1 ratio (with consequences that I do not
understand,
> apart from a necessary change in the amount of time the
film stays in
> the developer).
>
> I'm assuming a similar concept applies to powdered fixer.
>
> If someone can suggest a website that contains Everything
You Want To
> Know And Then Some, I would greatly appreciate it.
If you are talking about packaged chemisty there are
usually complete instructions on the package. For powder one
starts with something less than the final amount at a
specified temperature. For most powdered chemistry the
starging amount is around one half to three quarters of the
final amount. For most developers the temperature is 125F,
for Kodak fixer its 90F. After everything goes into solution
cold water is added to bring the volume up to that required.
If you are interested in mixing your own it becomes harder
to find anything current with general instructions. My
suggestion is _The Darkroom Cookbook_, Steven Anchell,
Butterworth-Heinemann ISBN 0-240-80196-2 This is in print
and easily available.
Mixing from scratch is not at all difficult and is fun.
You can mix solutions which are not available packaged and
sometimes save a littl money. The last is sometimes not true
because packaged chemistry, especially in small amounts is
pretty cheap.
--
---
Richard Knoppow
Los Angeles, CA, USA
dick...@ix.netcom.com
Francis A. Miniter
>I am familiar with the basics of processing a roll of B&W film, i.e.
>developing the negatives and making prints. HOWEVER, I have never
>mixed chemistry. In the near future I plan to begin doing so.
>
>I've done a lot of searching on the internet and reading various books
>in the library, but so far I've only come across rather non-specific
>descriptions of the process. Typically, such articles will say "mix
>the chemistry according to the manufacturer's instructions." However,
>I've examined a packet of D-76 powdered developer and didn't see
>anything that resembled specific instructions.
>
>My highly tentative understanding of mixing, say, D-76 developer is as
>follows:
>
>* If I have a "makes one gallon" packet of D-76 powdered chemical, I
>am to mix that into 1 gallon of water and store the result in a
>suitable container. I can then use that mixed solution full-strength,
>or diluted at a 1:1 ratio (with consequences that I do not understand,
>apart from a necessary change in the amount of time the film stays in
>the developer).
>
>I'm assuming a similar concept applies to powdered fixer.
>
>If someone can suggest a website that contains Everything You Want To
>Know And Then Some, I would greatly appreciate it.
>
You have a lot of questions packed in there.
1. Mixing Packaged D-76. First, as you are starting out, got for
the one quart (one liter) size, not the one gallon. Obtain a one
quart/one liter graduated cylinder. I measure metrically, so I will
continue with metric measures here. Fill the graduated cylinder to
about 700 ml with water at 125° F. (buy a digital thermometer from a
kitchen store). Slowly add the D-76 mix while stirring gently with a
plastic stirrer (available from any photo supply store or kitchen
store). This will increase the overall volume to about 800 ml. There
will still be some chemicals left in the package. So pour some hot
water into the 'empty' package and pour it into the graduated cylinder.
You will now be about 900 ml. Add water to make 1,000 ml (i.e. one
liter). Pour the entire mixture into a storage container. For
developers, I prefer a glass (brown or green if possible) container with
a plastic top. Allow to sit overnight before use. This assures that
the mixture has properly gone into solution. Store your developers in a
refrigerator at 40° F. to retard the rate of oxidation.
2. Mixing fixer. If the fixer contains sodium thiosulfate
pentahydrate (as opposed to anhydrous), the water needs to be at 125° F.
. The reaction is endothermic and the solution post mixing will be
about 70° F. Start with about 600 ml of water, as the pentahydrate
contains water itself.
3. You can mix D-76 from scratch materials more cheaply than you can
buy it. And this allows you to mix other developers and more than one
fixer as well. For this you will need a good balance. Digital ones are
available for about $100, but you can buy a used triple beam balance on
eBay for under $40. A supply of different size graduated cylinders is
useful. I have 40 ml, 250 ml, 500 ml, 1,000 ml as standard measures.
4. Using D-76. I started out using D-76 full strength and found
that by roll 6 I was worried about development time and exhaustion of
the developer. I have switched to using it 1:1 and throwing away the
once used solution. The micro-image is finer this way and I know that I
always have fresh developer to use.
5. Literature. I second Richard's suggestion that you get
Anchell, The Darkroom Cookbook, and also suggest Anchell and Troop, The
Film Developing Cookbook. No working darkroom should be without them.
6. Chemistry Safety and Technique. Safety. There are numerous
safety issues, such as never add water to a strong acid. Always add the
acid - slowly - to the water. Work in a well-ventilated area. Wear a
respirator (Sears has adequate ones) and gloves if the chemicals are
noted to be hazardous. I always do this for pyrogallol, glycin, and
color developers CD-3 and CD-4, as well as some other chemicals as
indicated on the label. Sometimes, e.g., when mixing packaged color
chemistry, the powders can be hazardous, so it may be advisable to
carefully slice open the package and lower it beneath the surface of the
water (gloves on) before emptying it out. This prevents the release of
hazardous powders into the air and assures that all of the chemistry is
in solution. When dealing with hazardous raw chemicals, pour water
into the container used to weigh them before dumping it into the
solution. This reduces the problem of powder in the air.
Technique. When making solutions from raw chemistry, the order in
which chemicals are added is sometimes important. Some developers need
an alkaline environment in which to dissolve, so adding sodium sulfite
(or in at least one case, potassium carbonate) before the developer is
added is necessary. Consistency of procedure is necessary to obtain
repeatable results. Remember how you do a procedure and do it the same
way every time (unless you learn that it is wrong for some reason).
Enjoy.
Francis A. Miniter
Michael A. Covington
news:20gisv8d2rdag9ido...@4ax.com...
> I've done a lot of searching on the internet and reading various books
> in the library, but so far I've only come across rather non-specific
> descriptions of the process. Typically, such articles will say "mix
> the chemistry according to the manufacturer's instructions." However,
> I've examined a packet of D-76 powdered developer and didn't see
> anything that resembled specific instructions.
It may specify the temperature of the water to be used (warm water works
best, as I recall, but the temperature is very non-critical).
The instructions are probably something like "dissolve the powder in 3
quarts of water with continuous stirring and then add water to make a total
of 1 gallon."
And then you store it -- preferably divided up into four 1-quart bottles, so
you don't expose the whole thing to air whenever you use any of it.
Glass bottles are much better than plastic at excluding air.
> suitable container. I can then use that mixed solution full-strength,
> or diluted at a 1:1 ratio (with consequences that I do not understand,
> apart from a necessary change in the amount of time the film stays in
> the developer).
And saving money.
> I'm assuming a similar concept applies to powdered fixer.
Right.
There really isn't much more to know.
--
Clear skies,
Michael Covington -- www.covingtoninnovations.com
Author, Astrophotography for the Amateur
and (new) How to Use a Computerized Telescope
geo
> developing the negatives and making prints. HOWEVER, I have never
> mixed chemistry. In the near future I plan to begin doing so.
>
Mixing from scratch? You are required to go to:
http://www.photoformulary.com/DesktopDefault.aspx
Get Darkroom Cookbook as others recommended. You can get a cheap digital
scale for around $30. on ebay. Get one with at least a 200g capacity. You
can get by without a scale using the teaspoon conversion method in Darkroom
Cookbook but the scale is so cheap why not get one.
Use D76 1:1 one-shot. Easier & better grain & resolution. I prefer D23. Just
2 ingredients, works great.
http://unblinkingeye.com/Articles/DD-23/dd-23.html
http://www.photoshot.com/articles/general/kodak_d_23.htm
Frank J. Schifano
work well enough for this application. While it's true that glass is
absolutely impermeable to oxygen, the plastic bottles are plenty good
enough. They won't shatter and make a dangerous mess if (when) you
drop one, and they can be had for practically free. Go and price some
glass bottles and decide for yourself. Remove the label and indicate
the contents with a Sharpie. I've been using them for a good while
now and have not had any developer go bad from oxidation before it's
time.
Dan Quinn
>
> http://www.photoformulary.com/DesktopDefault.aspx
>
> You can get a cheap digital
> scale for around $30. on ebay. Get one with at least a 200g capacity.
Don't buy cheap and 200 grams is more than enough. Dan
Dan Quinn
> Just as an aside, I can tell you from experience that
> 1L soda bottles...
For some time I used 12oz square water bottles. Smaller bottles,
filled and sealed, used one at a time, may be a better solution
for you. Four 250ml water bottles will hold 1 liter of stock. Dan