New B&W 'Zine...? & Updates..

[scootermm]

I read through the article which seemed very descriptive but since you asked for feedback scott ... I wanted to comment on something in particular, only because I dealt with the same "math" problem recently.

When you are starting out, it would be a good idea to get some additional shot glasses, and mark them with the percentage dilution they will contain. The stock solution you get when you buy it is a 20% solution. Mark your shot glasses as 10%, 5%, 2.5% and 1.25%. Put one drop of NA2 in each glass. Using a different dropper, add 1 drop distilled water to the 10% glass, 2 drops to the 5%, three drops to the 2.5% and so on. If you need that much contrast, you can always pull the 20% direct from the bottle. You will find with use and practice that good negatives require very little contrast agent to make a good print, and that a very little contrast agent goes a very long way.

With my example print here, I am adding 1 drop of 2.5% NA2.

your dilutions are incorrect Scott.

you mention putting 1 drop of 20% in each shot glass that are marked 10%, 5%, 2.5%, 1.25%. and then sequentially adding 1 drop, 2 drops, 3 drops etc of dist water.

My understanding for the correct manner to dilute is as follows:

10%solution:
add 1 drop of distilled water to the 1 drop of 20% solution = 2 drops of 10% solution

5% solution:
add 3 drops of distilled to 1 drop of 20%= 4 drops of 5%

2.5% solution:
add 7 drops of distilled to 1 drop of 20% = 8 drops of 2.5%

1.25% solution:
add 15 drops of distilled to 1 drop of 20% = 16 drops of 2.5%

you have to double your total quantities, it is an exponential relationship not just an adding relations... not just add one drop to get different dilutions.

I went through a similar process although I am taking small bottles and making up solutions and storing each of my dilutions in seperate bottles marked 10%, 5%, 2.5%

10% solution:
5ml of 20% Na2 added to 5ml dist water = 10ml of 10% Na2

5% solution:
5ml of 20% Na2 added to 15ml dist water = 20ml of 5% Na2

2.5% Solution:
5ml of Na2 added to 35ml of dist water = 40ml of 2.5% Na2

Others can comment on this, or correct me, but Im pretty sure as I made a mistake at first and was corrected (by Kerik).

When people are taking notes about their prints using your calculations theyd actually not be listing the correct %Na2 drop.

[TheFlyingCamera]

Matt - I think you are absolutely correct about the math. I'll ask David to publish a correction with the drop counts amended.

[vickersdc]

The errant article has been corrected! Thank you scootermm.

[Kerik]

When I teach I find it easier for people to grasp this (nearly) math-free approach:

Starting with a 10 ml bottle of 20% Na2 solution and a total of 4 dropper bottles:

Take 5 ml 20% and dilute it with 5 ml distilled water = 10 ml of 10%
Take 4 ml of the 10% and dilute with 4 ml water = 8 ml of 5%
Take 3 ml of the 5% and dilute with 3 ml water = 6 ml of 2.5%

You end up with 5 ml 20%, 6 ml 10%, 5 ml 5% and 6 ml 2.5%

I've not found a use for lower concentrations than 2.5%, but I rarely print smaller than 8x10 and most often I'm printing considerably larger.

Pipettes and pipette pumps make these measurements easy and accurate. They are also much more convenient for measuring your pd and ferric when you're printing large. Counting 60 drops of anything really sucks. I like these pipettes because they are plastic and nearly unbreakable while the glass variety are easily broken.

[Kerik]

..

[scootermm]

Kerik... brilliant.

and so much easier.

[TheFlyingCamera]

Gentlemen-

This is wonderful feedback, and I appreciate Kerik's math-free approach to making the NA2 dilutions. My point in going with drops in the article was to allow someone who is NEW TO THE PROCESS to make up a small amount of each solution so they didn't feel they were wasting their expensive chemistry. I suspect that most people new to the process are not going to be diving in printing 12x20s.

[scootermm]

Originally Posted by TheFlyingCamera

Gentlemen-

This is wonderful feedback, and I appreciate Kerik's math-free approach to making the NA2 dilutions. My point in going with drops in the article was to allow someone who is NEW TO THE PROCESS to make up a small amount of each solution so they didn't feel they were wasting their expensive chemistry. I suspect that most people new to the process are not going to be diving in printing 12x20s.

Scott... VERY true, they will hopefully be printing the more manageable sizes (4x5/5x7/8x10/etc)
But along those same lines. Honestly, mixing them up into consistant bottles is, in my opinion, FAR MORE cost effective and simplified. If they buy a 10ml bottle of 20% Na2 and dilute it up specifically as Kerik mentioned, then they are going to have a stock working bottle that will allow them to pull their single drops from whenever they are in a printing session. I am printing 12x20, but regardless of that, I'm still using the "drop" method for the Na2 contrasting agent. For instance, if I were to need 1 drop of 5% Na2 for a 8x10 (or even 4x5/5x7) print, I may use 4 drops of 5% Na2 for a 12x20. The overall efficiency carries over no matter the size of the print.
This is merely the opinion of one person, but it seems alot more wasteful to have 4 shot glasses set out for each print... unless your intent is to take the unused drops in those 4 shots glasses and disperse them into seperate containers for the worker to use the next time around. Just seems like it'd be loads easier to just get that 20% bottle, dilute it out right off the bat and have those 5 ml 20%, 6 ml 10%, 5 ml 5% and 6 ml 2.5% on hand and ready to roll with whenever the need arises.

again though, just my opinion, and comes from my working experience thus far.
Like I said initially, wonderful that you took the time and effort to put this walkthrough together. Hopefully it will be beneficial to many.

[TheFlyingCamera]

I don't usually put out all four shot glasses anyway- I'm usually working with just a single glass with a single contrast grade mixed up in the minimum quantity I need for that printing session. I rarely have time to make more than about four or five prints in a single printing session (day job, you know). The next time I order a bottle of NA2, I'll have to get a pipette system and measure out my NA2 in separate bottles.

[RobertP]

With a 1ml pipette you can dispense 0.005 ml of solution which provides greater accuracy than the photographic process allows. So there is no need to mix 5 and 10% solutions. You can dispense the amounts needed right from the 20% solution. I use glass pipettes because the very small orifice size at the tip of the pipette. I can't comment on the plastic ones. The glass ones put out a stream that is so fine that it is even hard to see as you are dispensing it. I just seem more comfortable with the glass pipettes because it seems there is less chance on the orifice size changing with continued use. But then again I haven't used the plastic ones so I can't actually comment on how well they work. Plus they all (glass or plastic) are dirt cheap and normally come in packs of three. I worry more about handling the bottle of Na2 than I do about breaking a pipette. But with a 1ml pipette you can dial in the amounts with the 20% solution even if your total coating mixture is only 1ml. This makes the Na2 process that much simpler as you are only dealing with one bottle of Na2 instead of three or four. Arentz explains it in great detail in his second edition p. 56-60. Robert