Platinum Printmaking - Chapter 6


You should have at least one test print at this point. If you followed the "step" method outlined in the last chapter, you've got a print that doesn't look like much, but it can tell us a lot.

What We Have

Before we get started, the test print needs to be absolutely dry. If it feels at all cool to the touch, it probably isn't dry yet. To speed things along, you can use a fan or a blow dryer. Just don't get the print anything more than warm, so the paper isn't at risk of discoloring, and use plenty air to carry away the water vapor. After it's dry, let it dry a little more just to be sure.

You may have noticed that some of the more exposed steps on the test print looked pretty good in the clearing bath, and some of the less exposed steps looked washed out. But now that the print is dry, the well-exposed step has probably moved at least one minute up the exposure scale. Photographers who normally print on commercial enlarging paper will find this to be the opposite of what they expected. Commercial papers usually look darker when they are wet and dry lighter. This "dry-down" phenomenon makes reading a wet print difficult, but experience can train the eye pretty well.

Now that you have a dry test print in front of you, your eyes were probably drawn to the step with the best apparent exposure. But sometimes, looks can be deceiving. I prefer to block out all the steps, except one, and evaluate each step on its own merits. When I look at the steps all together, I find each step's appearance is colored by those adjacent to it. A darker step will make the one I'm looking at seem lighter, and a lighter step will make it appear darker. Even the tone of the material used to block out the other steps can have an effect, so I try to use something approximating the mat I'll be using or the processed substrate (compare the original paper you used to the test print, and you'll likely see a substantial difference between the two).

Trust your instincts to pick the best exposure, and you'll be ready to run one more test print. This time, we're going to narrow the exposure down to a 30-second interval. 30 seconds may seem like a long time, especially to the silver printers out there, but seasonal changes, printing a few hours earlier or later, or light cloud cover can make more difference than that for a printer using the sun. If you are using an artificial UV source, the exposure can be fine tuned even further—down to 10 or twenty seconds or as few exposure units on the integrator.

For the next test, figure your midpoint at the time it took to get the best exposure on the first test print. Then, add 30 seconds to and subtract 30 seconds from that time and make another test print using the same negative and coating formulation. This time, though, you will expose the paper in thirds—one third for the first 30 seconds, two thirds for the next 30 seconds, and the whole image for your midpoint time minus 30 seconds. That gives you a test print recreating your previously determined exposure and new steps halfway between that exposure and those immediately surrounding it on the first test print. After developing and drying the second test print, simply evaluate the exposures as before and pick the best one.

You may continue to run tests for as long as you like, but in most cases, 30-second intervals are fine enough. As I mentioned earlier, sun printers may not be able to maintain that much control over a even single printing session. After all, 30 seconds in six minutes is less than a 10% difference in exposure. Still, if you are a complete perfectionist and your light source is repeatable enough to warrant the effort, by all means, run as many tests as will make you happy.

First Real Print

We're done with testing and have established our exposure, so it's finally time to make that first real print. Everything is the same as before, but we are going to add one more helpful tool—the step wedge. A step wedge is a strip of film with graduated steps (what else?) from near 0% density (clear base) to near 100% density (black). We are going to use it to better evaluate your first finished print by comparing its steps to the print's changes in density. You don't need an expensive calibrated step wedge, so save your money for metal salts or a velvety single-malt and get a "plain vanilla" step wedge. There are several different sizes and configurations for step wedges, but what you want is a Stouffer T2115 (or something similar). It is about ½-inch wide and five inches long, with 21 steps from clear to black.

When you set up the printing frame for the next print, place the step wedge against one side of the negative. It doesn't really matter where you put the step wedge, but it needs to print on some of the coating that went outside the marked image area, and it's nice if the numbers on it read the right way around when you are evaluating the print, later. Now, expose the print for the time you determined in testing, and develop, clear and dry it.

This latest print should look pretty good, unless something went dreadfully wrong, and we are going to use the step wedge part of the print to get to know the image better. Start by punching a hole near the center and edge of the long side of one of test prints you made earlier (an office hole punch is the perfect size. To find the density range of your image, place the punched print facedown on the print you are examining so the image is uncovered and the step wedge print is visible through the hole. This isolates the wedge's steps in the same way as we isolated parts of the image on the test prints. Find the lightest and darkest areas with detail on your image and match them to individual steps on the step wedge. The number of steps from light to dark (or vice versa) tells us the image's density range. The film step wedge can also be used in this way on a light table to determine the density range of a negative.

To find the density range possible with your coating mix at the print's exposure, set aside the hole-punched paper and simply observe which step on the wedge is the lightest and which step is the darkest (all steps beyond these two are the same shade). The difference between the two is the total range possible with that coating formula at the given exposure. This range may be longer than that of your image, but it cannot be shorter.

That's just wonderful. We know the density ranges of the image and the coating, but what good does that do us? By themselves, those measurements don't mean a great deal, but with a little more information, we can learn how to jigger the coating formula and exposure time to make the best possible print of our image. Since the wedge steps are more or less precisely ½-stop apart, they can tell us not only in what direction changes should be made, but also how much of a change to make.

The following examples explain, in general terms, how to shift, expand, and compress image's density range. For more detailed information, please consult the subject's very thorough coverage in Dick Arentz's book.

Highlights and Shadows Too Dark—Reduce exposure 33% for one step (½ stop) less density in the shadows and evaluate new print for possible changes to sensitizer ratio.

Highlights and Shadows Too Light—Increase exposure 50% for one step (½ stop) more density in the shadows and evaluate new print for possible changes to sensitizer ratio.

Highlights Too Dark, Shadows OK—Increase restrained sensitizer ratio (for a 12-drop total sensitizer mix, add one drop of restrained and delete one drop of plain for a roughly one step (½ stop) change).

Highlights Too Light, Shadows OK—Decrease restrained sensitizer ratio (for a 12-drop total sensitizer mix, delete one drop of restrained and add one drop of plain for a roughly one step (½ stop) change).

Shadows Too Dark, Highlights OK—Decrease exposure 33% for one step (½ stop) less and evaluate new print for possible changes to sensitizer ratio (most likely reduce restrainer for final print).

Shadows Too Light, Highlights OK—Increase exposure 50% for one step (½ stop) more and evaluate new print for possible changes to sensitizer ratio (most likely add restrainer for final print).

Like the "expose for the shadows, develop for the highlights" guideline (I hate to call anything a rule) for film, the shorthand for platinum control is "expose for the shadows, change restrainer ratio for the highlights." It doesn't exactly trip off the tongue, but it works.


Up to this point, we have been working toward controlling the mechanics of the process well enough to get a reasonably good print and learning how changes to the process affect its end results. The best way to proceed from here is to practice the craft and make improvements by making mistakes. Also, it pays to keep track of everything you do, not making multiple changes at once, so when something serendipitous occurs, you'll know how you got there. And although I have recommended Dick Arentz's book throughout this tome, there were parts of it that read like Greek to me until I put the pieces together, myself, by trying things and seeing what happened.

Now, we are going to prepare for the day when you are finally satisfied with your work and want to display it. I don't make any claims to being an expert in this area, but I do know what I like, and I have learned from experts in the field how to properly care for a finished print. This section will cover different styles of printing, marking your work as yours, and protecting your prints from the world around them.

One of the most obvious differences in styles between printers is the type of border they leave around the printed image. Some, like me, prefer a clean, paper white border that shows no artifacts of the negative or the coating process. Others mask just outside the image area to get a clean black border, and still others use no mask at all to show the hand work (brush marks and such) in the coating material surrounding the image. If you choose the latter, you can still cover the border edges during the mounting and matting process to get a clean edge, but the hand-worked edges will be forever lost with the first two masked options. In the end, though, which style you choose to use is entirely up to you and your tastes.

If you choose to mask, the process is straightforward and easy to do. You'll need red graphic arts masking film and tape (I use Ulano Rubylith—its deep red color blocks UV radiation), a sharp razor knife (X-Acto or something similar), and a straightedge. I work on a light table, which makes things much easier, but it's not absolutely required. Start by cutting a piece of masking film about the size of the substrate you'll be printing on and attach it with drafting tape to a smooth work surface, dull side up. Next, mark out the four corners of your cutout on the masking film, and using the straightedge to get a clean line, make a light cut with the razor knife, connecting all the corner marks. Do not cut all the way through the film—all you are trying to do is cut through the thin red layer on top of the Mylar base. Finally, using the tip of the razor knife, lift one corner of the cutout and pull the red layer from the base, and you'll have your mask.

As with everything else we've covered so far, practice makes perfect when cutting masks. Your corners should be clean and square. A light touch on the knife cuts only the red film coating, not the base. And to save us all, the complementary red masking tape can be used to fix minor problems with the cutout.

To use the mask, flip it over so the shiny side is up and attach it to your work surface with drafting tape. Then, place the negative, emulsion side up, on the masking film and tack it to the mask at the negative's corners with small strips of red masking tape. Taping two diagonally opposed corners is usually enough to keep the negative in place. If you tack the negative to the other side of the masking film, you will pull up the red layer when you try to remove the negative, and the mask will no longer be usable. When handled with reasonable care, one mask can be used hundreds of times. Once the negative is masked, it can be loaded into the printing frame as normal, with the film's emulsion side against the coated paper and the mask against the frame's glass.

Other uses for masks include cropping an image and dodging/burning during exposure. To crop an image, simply cut the mask window to the appropriate size and attach the negative in such a way that the mask excludes whatever parts of the image you don't want to print. I save scraps of masking film to use as dodging and burning tools. For dodging tools, I just cut a rough shape from the film, attach it to a bamboo skewer, and move it over the area to be dodged during exposure. For burning, I cut a window in a larger sheet of film and use it to admit more light to confined areas of the print during exposure. Keep in mind that we are working with multi-minute printing times, so you may need to dodge or burn for a minute or more to get the effect you want. The step wedge on a preliminary print is particularly helpful in determining how much dodging and/or burning is required.

I also use masking film to add a step wedge during printing. After the window for the negative is cut, I simply cut a smaller window immediately adjacent for the step wedge and attach the wedge with red masking tape in the same way as the negative is attached. However, you should be careful that the step wedge is placed so it will not show when the print is mounted and matted.

When printing triptychs and diptychs (images made using multiple negatives) I use masking film to keep the negatives properly aligned, as well as to crop and clean up the borders. If they aren't attached to something, the negatives will move around as you load the printing frame. The result, more often than not, is a printed image that is distracting, rather than artistically inspired.

Prior to mounting and matting, you should mark your prints in some way. There are all sorts of schools of thought on this, but unfortunately, there are no rules for the "correct" way it should be done. Personally, I proudly mark my prints on the front and cut mat windows to show my mark. I generally use a No. 2 pencil and place my name to the bottom left, the title at the bottom center, and the edition numbering to the bottom right, just below the image.

I have also had a rubber stamp made, which I use on the back of the print to record all the pertinent information about the image. I only use archival ink on the stamp and test it on any new substrates to make certain it won't bleed or show through. And for good measure, I try to keep the stamp confined to the border area of the substrate.

Other printers mark different information on their prints or place it in a different order than I do. Some sign directly on the image, and some sign on the back. Some use ink, others use paste-on stickers, and still others use embossing stamps (like a notary's seal). Some mark with a logo "bug," and then there are those who make no marks at all. So, how you choose to mark (or not) your prints is a completely personal decision. I would caution, however, against using anything that could damage the image or the substrate or something that is fugitive. Specifically, beware of non-archival inks and adhesives that can attack the substrate or bleed through onto the image or border.

Another area of debate is the use of coatings on prints to protect them and/or enhance their appearance. Platinum images are already archival, so I find the rationale of protection a bit spurious, but it might have some merit in the case of a substrate that is easily deteriorated or that doesn't have a good "grip" on the platinum image. Some printers use wax or other substances to change the look of their platinum prints, deepening blacks and adding sheen to the surface. I am planning on experimenting with Renaissance Micro-Crystalline Wax (a conservator's wax finish) just to see what effects it might have, but I'm still leery of anything that hasn't stood the test of time with the platinum medium. I go to great lengths to ensure my platinum images will last (perhaps only to torture those who might view them long after I'm gone), and I would rather not introduce anything that could shorten their lifespans.

Mounting and matting of platinum prints are also areas of heated debate, but there are tried and true practices that will not harm your prints and help ensure their ongoing protection. First, absolutely do not heat or otherwise permanently mount your prints to backer boards. Heat can damage the substrate, and permanent mounting materials can attack the substrate or bleed through it. In addition, permanent mounting is the bane of conservators, because even if the adhesive can be detached from the backer, it will almost always remain in the substrate to some degree. Instead, use archival corners or mounting tapes. These archival materials either don't attach to the substrate at all or attach using reversible, chemically neutral adhesives, such as certain water-based pastes.

Mounting boards and mats should be 100% rag content and pH-neutral or lightly buffered. Ordinary mat board is made from wood pulp and may be heavily buffered to offset the pulp's naturally acid pH. If the acidity of this type of board doesn't attack the substrate or image, the buffering chemicals will probably migrate from the mat to the print. In addition, the buffering agents' effectiveness will dissipate over time, leaving the mat's inherent chemistry to damage the print. And while we are discussing mats—never, ever mount a print in direct contact with the frame's glazing. You would do better not to have any glazing at all than to condense contaminants on the it and trap them against the surface of the print.

I prefer to use modular metal frames for my work, because they have a clean, unobtrusive appearance and won't outgas,like some wooden frames can. If you choose to use wooden frames, avoid any that are made of composite wood products and seal any exposed wood surfaces with shellac for good measure. For short term display, you may also use so-called "frameless" systems that sandwich the print and mats between sheets of glass or acrylic, without a surrounding frame. The only problem with these systems is that they don't protect the edges of the stack from outside contaminants.

For glazing, I generally use UV-blocking acrylic (sold under the trade name Acrylite). It is virtually indistinguishable from glass in a frame, weighs less than glass, and is resistant to breakage. It's only real drawback is that it scratches more easily than glass. If you prefer glass, be sure to use a product that is "water white" and includes a UV-blocking coating (such as Tru Vue Conservation Clear). I do not use glazing that has a non-reflective or mat finish because the finish subtly alters the print's appearance.

Behind the mounting board I usually add a backer board and dust sheet to complete the framed package. I use archival corrugated board for the backer, so I'm not introducing contaminants at this stage and undoing all the hard work that has gone before. The dust sheet is optional and can be difficult to attach to a metal frame, but I think it is worth the effort. A dust sheet not only adds a finished, professional look to the framing job, but also helps seal dust and other airborne contaminants out of the framed package. In addition, it is a good place to attach a business card or logo and an envelope for any paperwork you might want to include with the print.

There are as many styles of framing and matting as there are people on this planet and there are some things that are generally considered "right" and some things generally considered "wrong" (such as having the narrowest mat border on the bottom). For my work, I know what I like—simple—but I do try to accommodate my patron's wishes when it comes to matting and framing.

Personally, I prefer a "natural white" mat that is cut to show about ¼-inch around the sides and top of the image and ½-inch at the bottom (to display the signature line). For 8x10 images, I use a 16-inch wide by 20-inch high black anodized frame and bevel-cut the image window in the upper third of the top mat. The top mat is four plies thick to give some depth to the window and keep the print well away from the glazing. This format is commonly called "gallery" or "museum" mounting because it provides an unobtrusive, uniform way of displaying a portfolio in such environs. I find it works very well for groupings of prints, and it isolates the image without distraction while drawing the viewer in.

Unmounted, thoroughly dry prints can be stored in an archival box or archival sleeves, away from sources of excessive heat and/or humidity. They should not be stored in anything that has not been tested and proven to be made of archival materials, just as you wouldn't use pulp mat board to mount and display them.

You Made It

Well, you made it to the end of this thing. I admire your perseverance and hope what you learned here was helpful and inspirational. As you may have realized by now, I love what I do, especially the surprises that come along most every day. Whether it is a scene I absolutely have to capture with my camera, a print I'm making for the first time coming to life in the developer, or someone admiring (or not) a piece of my work, it's all good.

I plan to continue updating this document—adding illustrations and photographs are high on the list—to make it more useful, and I would appreciate any input you might have. Are there parts that are confusing or unclear? Are there errors of fact or omission or grammar/spelling/ punctuation? Did it bore you to tears? Whatever constructive criticism you might have, I would certainly love to hear. Also, I'm more than happy to answer any questions you might have, especially the "dumb" ones (those are much easier to answer than the really hard ones).

Please feel free to contact me by any of the means listed in the About Us section of this site.