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Photo Engineer
11-03-2006, 06:40 PM
For the last few days, I have been making comparisons of the sharpness of hand coated prints using my own emulsions. This should also be true using Liquid Light and other similar products.

Sharpness appears to decrease in the order:

Baryta > Hot press untextured > cold press > cold press textured

Sharpness seems to decrease in the order:

Blade coated/dip coated > spray > brush

Since I have only done Blade, dip and brush, I cannot comment exactly on the spray coating other than what is published.

This work is based on making defninition chart exposures of negative and positive images (which reveal bloom and fill in).

Some of the papers tested include Strathmore, Lanaquarelle, Cranes, COT320, and a host of others including 3 grades of Baryta and RC.

All are acceptable and yield some spectacular results, espeically the textured Strathmore Watercolor which is simply beyond description for some pictures (but is not very sharp). I think Denise Ross has said it best. These images can be stunning and repeat what some of the old textured surfaces gave us.

I encourage you all to try making your own coatings on some of the textured papers out there. Please be aware that you must coat more emulsion on cold pressed papers than on hot pressed papers and you must 'learn' how to do this. It is like learning how to paint a picture with extra steps.

My best wishes to all of you who try it.

PE

dwross
11-03-2006, 07:04 PM
I think I'm finding that the developer makes a difference, too. I'll be more sure of that after a couple more runs of tests. My results this week are up here: http://dwrphotos.com/blog/EmulsionResearch.htm#Current and one date back (Oct 30 - Nov 3)

I'm with PE in encouraging more folks to work on this. I just finished reading "Memoirs of a Photochemist", by Fritz Wentzel, and I was struck by how the past and future keep circling around each other. In many ways, APUG'ers are recreating the excitement and investigative energy of those early photographers. So much knowledge has been lost and even small machine shops and mechanical skills are getting harder to access. We're pioneers and historians at the same time. Very cool.

Donald Miller
11-03-2006, 09:28 PM
Excuse me for asking what seems to me to be obvious. If we are going to engage in hand coating our printing materials, why not go to a known process and go with pt-pd? Or even Kallitype toned in Pt which seems to be indistinguishable from pt-pd.

The collectors of photographic art will buy pt-pd ten to one over silver.

Photo Engineer
11-03-2006, 09:40 PM
Printing speed, grades, tone, and a host of other advantages.

But then you might be right.

PE

dwross
11-04-2006, 08:51 AM
A knownprocess? Where's the fun in that? And, if money if the motivation, photography may not be the very best profession to be in. Far more important is this: they are different works of art, as different as watercolor is from oil. Color, texture, appearance, best negatives for the process - all different and in my opinion, viva la.

Donald Miller
11-04-2006, 08:58 AM
Certainly true that each has it's own advantages. Pt-pd does have the capability of altering contrast contrary to popular belief. The advantages of Pt-pd are longer tonal scale. The disadvantage, to some, is lower dmax than silver.

The fun in doing something that is known is not having to reinvent the wheel at each and every turn. I have lived the better part of my time on this earth and would rather spend it making good photographs. But to each his/her own.

Photo Engineer
11-04-2006, 09:42 AM
Donald, I've often wondered about that. It seems to me that a longer tonal scale and a lower dmax are contradictory, as a longer tonal scale to me requires a higher dmax.

In any event, if you make your own emulsion you can control the tonal scale rather than take what the manufacturer thinks you should have.

You are correct about contrast, I had forgotten that, but can you devise a range over 4 grades? You can with silver. IDK personally if you have that range with Pt/Pd.

And, you can keep the emulsion for quite a long time, as well as the coated paper or film. Can you do this for Pt/Pd? I really don't know.

I'll probably think of more reasons, but cost comes to mind as well. Silver nitrate costs a LOT less than either Pt or Pd salts.

PE

Donald Miller
11-04-2006, 10:01 AM
Yes, cost is a factor...no doubt about that. But I think that is offset by the higher esteem in which Pt-pd prints are held by most.

I think that because of the higher cost and perhaps the greater degree of experience/knowledge that pt-pd printers usually possess, that most know how to expose and process the camera negative so that it exhibits repeatable and foreknown density scale characteristics.

The one characteristic that hand coating silver would offer is that the print would exhibit more of the pt-pd characteristics so far as the emulsion residing within the paper rather than sitting on the baryta layer.

So far as the requirement of a long tonal scale requiring a high dmax, I don't follow your reasoning on this. The difference in the materials is such that the dmax (whether it is 1.65 or 2.10) is not related to the distribution over which the rest of the tonal scale is represented.

Photo Engineer
11-04-2006, 10:22 AM
Donald, the tone scale is the total length of the sensitometric curve from where the curve starts to rise above dmin (toe) to where it levels off at dmax (shoulder). If the dmax is lowered, then the shoulder is closer to the toe and the tone scale is shorter. That is the definition I learned at EK with all of the diagrams and technobabble removed.

PE

David A. Goldfarb
11-04-2006, 10:40 AM
I'd bet you that Strathmore 500 Plate finish falls somewhere between baryta and hot press watercolor paper. This is what I'm using for albumen.

Photo Engineer
11-04-2006, 10:43 AM
David, I use the Strathmore Smooth, as I can't get the Platae. I used the cold press Watercolor. I have not found any hot press. The finish on the cold press is beautiful, but it is hard to coat. I think I showed you some examples of that.

PE

David A. Goldfarb
11-04-2006, 10:54 AM
Yes, I've seen it, and I've also tried some Arches cold press and Arches hot press for albumen and for Polaroid transfers--both very nice papers.

PM me your address, and I can send you some Strathmore 500 1-ply Plate to experiment with. I've been buying it online from Jerry's Art-a-rama.

Photo Engineer
11-04-2006, 11:01 AM
Yes, I've seen it, and I've also tried some Arches cold press and Arches hot press for albumen and for Polaroid transfers--both very nice papers.

PM me your address, and I can send you some Strathmore 500 1-ply Plate to experiment with. I've been buying it online from Jerry's Art-a-rama.

David, thanks, but I can order it. I have to get several types of paper support and some film supports as well.

I really appreciate the offer.

PE

Kirk Keyes
11-06-2006, 03:09 PM
Donald, the tone scale is the total length of the sensitometric curve from where the curve starts to rise above dmin (toe) to where it levels off at dmax (shoulder). If the dmax is lowered, then the shoulder is closer to the toe and the tone scale is shorter. That is the definition I learned at EK with all of the diagrams and technobabble removed.

PE

Perhaps Donald is referring to the exposure range...

I hear people often (just this last weekend actually) say pt-pd has a "longer" tonal scale, much like they say that Azo has a "longer" tonal scale. They seems to be confusing either the exposure range of the paper, or they percieving something that is not backed up by math/physics/optics.

Donald Miller
11-06-2006, 04:38 PM
Perhaps Donald is referring to the exposure range...

I hear people often (just this last weekend actually) say pt-pd has a "longer" tonal scale, much like they say that Azo has a "longer" tonal scale. They seems to be confusing either the exposure range of the paper, or they percieving something that is not backed up by math/physics/optics.

Whatever the correct term is, what I mean is that pt-pd and grade two Azo, for that matter, will require a camera negative with a greater density range than an equivalent grade two photographic enlarging paper. (1.65- 1.70 vs. 1.10 -1.25)

Yet when we examine the characteristics of prints made from optimally produced negatives, pt-pd will not have the dmax of a silver print. So if you have an explanation for that, I am open to hearing it.

Photo Engineer
11-06-2006, 05:26 PM
Donald, what are the contrasts of those two negatives though? That is what also enters into the final print. That density range may have been achived by a variation in the negative contrast which makes a big difference in the final print.

I might also add that both Azo and Pt/Pd have a majority of their sensitivity in the UV region and visual contrast may therefore be misleading even when using a tungsten bulb.

PE

Kirk Keyes
11-06-2006, 06:49 PM
Whatever the correct term is, what I mean is that pt-pd and grade two Azo, for that matter, will require a camera negative with a greater density range than an equivalent grade two photographic enlarging paper. (1.65- 1.70 vs. 1.10 -1.25)

This is known as the Exposure Scale. It's the x-axis in your BTZS software.


Yet when we examine the characteristics of prints made from optimally produced negatives, pt-pd will not have the dmax of a silver print. So if you have an explanation for that, I am open to hearing it.

This is the Density Scale -From Answers.com:
A value for the range density for a photographic material that corresponds to the difference between the maximum density and the minimum density. Also known as net density.

It's the y-axis on the BTZS software.

You're comparing apples and oranges when you ask that question.

The Azo and pt-pd paper have a low contrast, hence the greater exposure scale than greade 2 silver paper. Combine this with negatives that have a high density range, and you get a print of normal reproduction range.

The Azo print will produce the neg with greater d-max than the pt-pd, but the same range of exposure scale is recorded onto the paper. (By the way, my Ilford MG IV FB with grade 00 can print that same negative exposure scale range.)

I'm sure PE can explain the multiplication of negative and paper gradients/contrasts to come up with a normal reproduction range and how it applies to this question better than I...

Photo Engineer
11-06-2006, 06:57 PM
Kirk;

Thanks, you did so well, I don't think I need to add anything, unless Donald wants more detail about curve shapes.

PE

Donald Miller
11-06-2006, 07:52 PM
This is known as the Exposure Scale. It's the x-axis in your BTZS software.



This is the Density Scale -From Answers.com:
A value for the range density for a photographic material that corresponds to the difference between the maximum density and the minimum density. Also known as net density.

It's the y-axis on the BTZS software.

You're comparing apples and oranges when you ask that question.

The Azo and pt-pd paper have a low contrast, hence the greater exposure scale than greade 2 silver paper. Combine this with negatives that have a high density range, and you get a print of normal reproduction range.

The Azo print will produce the neg with greater d-max than the pt-pd, but the same range of exposure scale is recorded onto the paper. (By the way, my Ilford MG IV FB with grade 00 can print that same negative exposure scale range.) This is the point that I was trying to make in my earlier comment. However your MG IV FB will not be the same print as a Pt-pd or even an Azo print. It will not have the presence that Azo will show...and it will not have the delicacy of tone that a platinum print will have.

I'm sure PE can explain the multiplication of negative and paper gradients/contrasts to come up with a normal reproduction range and how it applies to this question better than I...

This still does not answer the position that PE made that higher dmax is necessary for a longer tonal scale. If a material such as Azo Grade two has an exposure scale of 1.65-1.70 and a grade two material such as Nuance has a exposure scale of 1.25 with a condenser enlarger than something is darned sure different. I agree that it takes a negative of corresponding density range (high density minus low density and not minus FB +fog) to match the paper. The paper or process (in the case of Pt-pd is longer scale) or lower contrast in your description.

By the way, PE, I do understand curve shapes so there is no need for you enlightenment on that score.

Photo Engineer
11-06-2006, 08:37 PM
Donald;

If two papers are identical in all ways but dmax, the paper with the lower dmax is necessarily shorter in latitude and will reproduce a shorter tone scale.

I think that you can see the logic in that. You can demonatrate that for yourself by taking a paper curve from the Kodak web site and altering it to show the two curves.

Without such curves, I guess this is about all I can do in the way of explanation. I hope it helps.

There are other curves possible, but this is the simplest case. I hope it helps you.

Use what works for you or what you like best though.

PE