cyanotype QUICKIE


NB: forbered blandingerne mindst 24 timer før de skal anvendes.
– Opbevar begge opløsninger i brune lufttætte flasker
– marker flaskerne med navn, dato og blandingsforhold.

DESTILLERET VAND :21°C
Blanding A: Ammoniumjerncitrat
100 ml (50 ml) distilleret vand ~21 °C
20 g (10 g) Ferric ammonium citrate (green)

Blanding B:  blodludssalt, rødt
100 ml (50 ml) distilleret water ~21 °C
8 g ( 4 g) Potassium ferricyanide

 

 

Cyanotype maskeringer

til inspiration – det praktiske er ikke løst endnu

Cyanotype toning: the basics « MP Photography

“No one but a vandal would print a landscape in red, or in cyanotype.” (Peter Henry Emerson: Naturalistic Photography for Students of the Art, London: Sampson Low, Marston, Searle and Rivington, 1889) Citation courtesy of Luminous Lint/Mike Ware.

I happen to agree with Mr. Emerson so I tone pretty much all of my cyanotypes.  I have several posts about different toners and how they (generally) look, but this post will go over the basic process of toning and try to troubleshoot a few common problems.

Toning a cyanotype involves two basic steps: a bleach phase, and a toning phase.  Every toner I know of contains some type of tannin in it: tannin chemically binds to the iron in the emulsion and changes the color.  If I understand this process correctly, it produces a form of gallic acid – used in dyes and inks, especially medieval ones.  I’ve read that gallic acid is normally corrosive, but I’ve never found this to be the case with toned cyanotypes.

If you’re concerned about the archival quality of your toned cyanotypes, Dr. Mike Ware (inventor of the ”New” cyanotype process) has said that his family photo albums contain what he’s pretty certain are toned cyanotypes – because they look very similar to other alternative processes it’s easy to confuse with Van Dyke prints or Kallitype prints.  I’ve personally never had issues with mine – I’ll get back to you in some 20 years or so and see if that’s still the case.

Keep in mind that toners are funny things – you can mix and match things, you can vary the sequence of bleach and toner and get different results.  I have a lot of good results with simply leaving the prints in the toner for long periods of time without bleaching at all.  Take things one at a time – don’t try to tone or bleach multiple prints together.  Experiment and have fun with it!  Just remember that the key to a successful toned print is to wash well between steps.

1. Toning Preparations:

Before you start your toning, always:

  • Age your prints at least 24 hours for the emulsion to harden.
  • Pre-wet your prints in filtered water to allow the solutions to penetrate the paper fibers evenly.
  • It’s a good idea to have multiple prints – toning is fickle, you never know what you’re going to get.
  • Plan to leave the print face down for long periods of toning, or plan enough time to “babysit” the print – agitate it while face up in the toner.

2. The Bleach Phase:

Bleaching is a tricky thing.  The purpose of bleaching is to help break down the iron a little so that the tannin in the toner can “grab on” easily.  If your water is heavily chlorinated, you may not even need to bleach your prints.

How much you bleach really depends on how you coat, how much emulsion is on the paper, and what toner you’re using.  If you bleach too far, you lose shadow density.  If you bleach too little, your shadows will stay a stubborn blue shade while your highlights cooperate.

Bleach types: the most common form of bleach solution is Sodium Carbonate.  That’s Washing Soda, usually found in your grocery store’s cleaner aisle, or at a photography chemical supply store.   Don’t confuse this with Sodium Bicarbonate – baking soda – it won’t react the same way.

Other types of bleach that I’ve used are Ammonia and regular chlorine bleach.  Ammonia stinks, horribly, and usually produces a browner image.  Chlorinated bleach destroys paper fibers and is better left to your laundry.

My typical bleach solution is about 1-2 teaspoons of Sodium Carbonate combined with 1 Liter of water.  If your print turns a bright purple the second you place it in the solution, it’s too strong.   Play with the solution until you’re comfortable with the rate of bleaching.  As you practice bleaching, you’ll notice that it’s a good idea to yank the print out a few seconds before you think it’s ready – the print will continue to bleach a bit while starting to rinse.

Always rinse the print well in running water between the bleach phase and the toning phase.

3. The Toning Phase:

All cyanotype toners are pretty much variations on a black/brown/purple theme.  Certain toners are more efficient and stain less, while other toners produce a wider range of possible colors.  Keep in mind that all toners will stain your paper base a little despite your best efforts.  (please note that the following links lead to blog post about the toners, or examples of the toner shade.)

Tea toner:  Most tea toners that I use are brewed for about 10 minutes in  25o mL of hot water, then added to a 1.5 Liter of room temperature filtered water.  I use about 8-10 small tea bags, not a very accurate measurement!  Every type of tea has a different quality or color to it – make sure that you use teas with tannin in them like black tea or green tea – white tea, red tea, and most herbal teas don’t have enough tannin to do anything to your print.

Green tea produces an eggplant/black shadow, and is so mild that it doesn’t stain the paper base too badly.  If you’re toning a high key image, green tea will sometimes produce a really cool pink highlight.  It has a tendency to split tone for me because of my double coat of emulsion.

Black tea will stain your paper the most, but it produces a lovely warm black/brown shade that’s nearly impossible to get anywhere else.  I generally use a Lipton tea product for iced tea, but any black tea will work.  If you want an easy split toner with warm highlights and blue shadows, black tea is the fastest way to get it.

Earl Grey tea: avoid this one – it has a lot of oils in it that can damage your print.

Tea toners work really well with a minimum of bleaching, but they do require a longer immersion for the iron to shift.  I normally tone prints in tea for about 2 hours, but depending on the print, it’s taken up to 8 hours.  Some people suggest that tea toners should be hot for a faster toner – in my experience that shaves about 30 minutes off the toning time, and stains the paper much worse.   It’s a good idea to let the print sit in clean filtered water for about 10 minutes before the final rinse to help remove some of the excess tannin.  All tea toners should be used freshly brewed – they lose potency after a day and should not be reused.

Tannic Acid Toner:  This stuff is a royal pain to work with.  It can produce the closest thing to a true black, but it’s far more likely to screw up, or produce a weird purply brown shade.  It has the widest range of color tones that I’ve seen in a toner, but you have absolutely no control over what you get.  Be extremely careful how much bleaching you do, because this toner is totally unforgiving if you go the slightest bit too far.

Done well, this toner produces the least paper staining – however, I’ve run into some chemical issues that I don’t quite understand that leave my paper the shade of cardboard.  (I’ve narrowed it down to interactions with the tap water, or the age of the toner.)

Tannic Acid is produced from wood chips, and is extremely hard to mix into a solution.  It’s a gummy mess.  Because of this it’s difficult to estimate how much I use, but generally about a Tablespoon mixed into a Liter of water is a good place to start (and then remove the gummy bits.)  A good tannic acid solution should be almost clear, and will take a minute of sitting in filtered water to fully tone out.  Toning times for tannic acid are usually quite short.

If mixed with distilled water, tannic acid toner will last for a few weeks/months.  A little mold is normal, just filter the solution every time you use it.  Once the solution starts turning a dark brown or granulating (tiny little granules appear – not sure what they are) it’s time to start fresh.  Tannic acid is also quite expensive, and only available at a photography chemical supply store like Photographer’s Formulary.

Coffea TonerI love coffee toner.  It’s a cold toner, as opposed to the warmer tea shades, and it leaves the paper pretty close to the original color.  It will still stain, just not as badly as tea.  Coffee doesn’t produce a true black, but more of a blue/black like a blackbird’s feathers.  The highlights will stay pretty clean so make sure your contrast is good and your highlights aren’t blown out.

I generally use the cheapest instant coffee I can find – about 4-5 heaping tablespoons of instant coffee dissolved into 250 mL of hot water, then added to 1.5 Liters filtered room temperature water.  I’ve read that other people have great success re-brewing used coffee grounds – since I don’t drink coffee I can’t exactly test this.

Coffee toner doesn’t seem to take quite as long as tea toner, but expect at least an hour of toning, perhaps more.  Again, it’s a good idea to let the print rest in a water bath before the final rinse.

Wine TanninThis is my new favorite toner, and I don’t have that much experience with it yet.  So far, it produces a nice dark shadow and a brown/tan highlight on a fairly regular basis.  It can be rather fickle if you keep the solution for a long period of time, so I suggest storing this toner no more than a month.

Wine tannin is basically the same thing as tannic acid, but produced from a different source.  It’s designed to use in microbrewing so it mixes into solution a lot easier.  It leaves the paper almost paper white, producing almost no staining.  It’s slightly cheaper than tannic acid, but since it requires more to produce the same effect – half an ounce of wine tannin mixed into 1 L of water – the price is probably pretty close.  I use the powdered version, but some stores have a liquid solution available.

Wine tannin has a tendency to put any coating discrepancies on display.  Unless I use the Christopher James variation listed in the link (toss the print into the tannin instead of bleaching first) I lose some of my highlight detail.  Like the tannic acid, it works pretty quickly.  Wine tannin also has a weird chemical reaction that can turn my paper to a cardboard brown, requiring a water bath before the final rinse.

Troubleshooting:

1. My print looks faded!  What happened?  You probably bleached the print too far.  Try test strips in varying times to get a better idea of what works – the ideal is to tone your shadows dark without losing highlight details.  Usually this means bleaching until the shadows are a dark purple and the highlights are slightly yellow.

2. I left the print in the toner forever, but it’s still blue!  What now?  Rinse the print for at least 5 minutes and go back to the bleach bath.  After bleaching again – just a little, rinse it again for 5 minutes and put it back in the toner.  Your initial bleach probably didn’t break the iron down enough.

3. The print toned nicely, but now that it’s dry I hate it!  Why does it look so flat?  I don’t know why, but that’s normal for a toned cyanotype.  Try brushing a diluted solution of acrylic gloss medium onto the print to bring back the shadow depth and give the surface a little shine.  It will look like it did when the print was wet.

4. Why can’t I produce the same results each time?  What am I doing wrong?  Nothing.  That’s a quirk of toning.  If you have a batch of prints that need to look similar, try toning them all at the same time with the same solution.  Otherwise you run the risk of variations that you may or may not like.  If you’re still having issues, stick with the basic tea toner – it’s a little less fickle.

5. My print looks mottled – it didn’t tone evenly.  What’s going on?  If you’re leaving the print in the toner for a long period of time, make sure you place it face down.  Paper floats oddly, and you may end up with “dry” spots that don’t tone evenly.  If you’re toning face up, make sure you agitate the print constantly.

6. My print has a bright blue round spot on it!  Yup, the curse of the air bubble strikes again.  Make sure the print is lying face down – ease the print into the toner slowly and work all the air bubbles out past the far edge.  If you already have the blue spot on it, try a quick rinse, bleach bath, and return the print to the toner for a bit to remove the blue.

7. My shadows are blah.  What happened to my perfect exposure?  Your original shadows need to be a nice, deep, cobalt blue to tone dark.  If your shade of cyanotype isn’t dark enough, it’s not going to tone well.  Read this tutorial and do some experimenting with your paper and your developer first before you try toning again.

Cyanotype toning: the basics « MP Photography.

 

CYANOTYPE TONING

by Steven Berkowitz

There are three types of chemicals that affect Cyanotype prints.
These chemicals can be used singly.
One approach is the bleach the color out of a dark print.
Another is to intensify the color of a normal print.
A third is to alter the color of a print. And then there are a slew of combinations.

With Silver prints a common practice is to bleach the color out of the silver and then re-develop the print in either Sepia or another Developer. This same technique can be done by combining a bleaching step with a toner step. The most common combo for Cyanotype is Sodium Carbonate and Tannic Acid.
Many of these recipes can be used in either direction, or repeatedly back and forth, each time producing a different tone. And each time you print, different tones may result.

Reducers – act as bleaches, degrading the blue color in the print
Sodium Carbonate, Ammonia, Clorox, TSP, Borax, Dektol …

Intensifiers – deepen the color of the print
Hydrogen Peroxide, Citric Acid, Lemon Juice, Vinegar…

Toners – change the color of the iron in the print
Tannic Acid, Oolong Tea, Wine, Cat Urine, Pyrogallic Acid…

General Considerations:
Overexpose prints to be toned by at least one stop (until the highlights are gray).
Prints should cure at least one day after printing.
Soak the prints in distilled water before you start toning.
Do a final wash for 10 ~ 15 minutes in running water at the end.
Replace the chemicals as soon as they start to get dark (maybe 15 prints per tray).
Always rinse between chemicals to increase toner life by about 5 prints per tray.
Always add chemicals to water, not the other way around.

Recipes :
Yellow – Blue Split Toner  Sodium Carbonate Household Bleach or TSP [reduction]
tray 1 – distilled water – soak for 5 minutes until thoroughly soaked
tray 2 – 1 pinch of Sodium Carbonate in 1 quart distilled water
immerse for less than a minute – the print will begin to degrade if left too long
tray 3 – distilled water
pull the print quickly from the Sodium Carbonate and watch the split
final wash – 10 ~ 15 minutes in running water
note: TSP (Tri sodium Phosphate) commercial cleaner can make a yellow & white print
note: Clorox household bleach can remove Cyanotype completely from parts of a print.

Deep Blue Toner – Hydrogen Peroxide [intensification]
tray 1 – distilled water – soak for 5 minutes until thoroughly soaked
tray 2 – 5 tsp. Hydrogen Peroxide (or vinegar, lemon juice [acidic]) in 1 quart. of distilled water
agitate the print until darkening stops (several minutes)
final wash – 10 ~ 15 minutes in running water
note: this chemical simply accelerates the oxidation process that will occur anyway as the print dries.

CYANOTYPE TONING – redevelopment

Red–Brown Toner Tannic Acid > Sodium Carbonate
tray 1 – distilled water
soak for 5 minutes until thoroughly soaked
tray 2 – 9 grams Tannic Acid in 1 quart of distilled water [or Oolong Cha (tea)]
agitate the print 30 seconds to 5 minutes
you will not see a color change until you put the print into the Sodium Carbonate!
tray 3 – distilled water – wash for 5 minutes
tray 4 – 1.5 tsp. (4.5 grams) Sodium Carbonate (Washing Soda) in 1 quart. of distilled water
agitate the print until the desired color is reached
optional – 5 tsp. Hydrogen Peroxide in 1 quart of distilled water
agitate the print to intensify the color
final wash – 10 ~ 15 minutes in running water

You can go back-and-forth with this, each time getting a different tone!

Eggplant–Black Toner Sodium Carbonate > Tannic Acid > (Sodium Carbonate)
note: you can do the above in reverse order for a different effect,
Soak the print, put it Sodium Carbonate very briefly until it starts to bleach then transfer to the wash tray and watch it bleach (note: Sodium Carbonate will continue to bleach even after it is put in to a wash tray!), put it in Tannic Acid until you get the desired tone, (optional) return the print to the Sodium Carbonate for a few seconds, final wash for 10 minutes.
You can go back-and-forth here also, getting a different tone each time!

Purple–Brown Toner Ammonia > Tannic Acid > (Sodium Carbonate)
tray 1 – distilled water
soak for 5 minutes until thoroughly soaked
tray 2 – 21 ml Ammonia in 1 quart of distilled water (acts as a bleach)
agitate the print until highlights bleach and shadows turn purple
tray 3 – distilled water
wash for 10 – 15 minutes
tray 4 – 3 grams Tannic Acid in 1 quart of distilled water [(or Oolong Cha (tea)]
agitate the print until the desired color is reached
optional – 1.5 tsp. Sodium Carbonate in 1 quart of distilled water until reaching a red-brown tone
final wash – 10 ~ 15 minutes in running water
You can also do the back-and-forth processing with this recipe.

CYANOTYPE TONING – color change

Violet Toner Pyrogallic Acid > Hydrogen Peroxide
tray 1 – distilled water
soak for 5 minutes until thoroughly soaked
tray 2 – 5 tsp. (10 g.) Pyrogallic Acid in 1 quart of distilled water
agitate the print until the desired color is reached
tray 3 – distilled water – wash for 30 seconds
tray 4 – 4 tsp. Hydrogen Peroxide in 1 quart of distilled water
agitate the print to intensify the color
final wash – 10 ~ 15 minutes in running water
You can also do the back-and-forth processing with this recipe.
note: this toner is greatly affected by water quality, humidity and type of paper used. It does not always work!
note: Tannic Acid and Gallic Acid have a similar effect, because Gallic Acid is anhydrous Tannic Acid (without water).

Eggplant–Red–Black Toner Dektol > Tannic Acid > (Dektol)
tray 1 – distilled water
soak for 5 minutes until thoroughly soaked
tray 2 – Dektol mixed straight from the Vat (or other hard developer)
agitate until a goldenrod color is reached
tray 3 – distilled water – wash for several minutes
tray 4 – Tannic Acid or hot Oolong Tea
agitate until a smokey black color is reached
final wash – 10 ~ 15 minutes in running water
optional – Dektol or Ammonia solution, followed by another 15 minutes final wash

Brown–Green Toner Dektol > Selenium
tray 1 – distilled water
soak for 5 minutes until thoroughly soaked
tray 2 – Dektol mixed straight from the Vat (or other hard developer)
agitate until a goldenrod color is reached
tray 3 – distilled water – wash for at least 1 minute
tray 4 – Selenium diluted 1 : 3 or more from the Vat
agitate until the desired color is reached, but not too long
be careful because Selenium contains Potassium Fericyanide, a bleach
final wash – 10 ~ 15 minutes in running water
You can also do the back-and-forth processing with this recipe.

Speckle Toning
Splash water across the surface of the print before immersing in water developing bath
Splash Dektol across the surface of the print while toning to make dark speckles

RESSOURCES
This information is garnered from several sources:
Photo-Imaging: A Complete Guide to Alternative Processes by Jill Enfield
Amphoto Books (October 2002)
ISBN: 0817453997

The Book of Alternative Photographic Processes – by Christopher James
Publisher: Thomson Delmar Learning; 1st Edition (June 2001)
ISBN: 0766820777

The Photographer’s Toning Book: The Definitive Guide by Tim Rudman
Amphoto Books (April 2003)
ISBN: 0817454659

and lots of studio experiments…

Sølvnitrat

frederiksen

Sølvnitrat er en giftig og ætsende kemisk forbindelse af sølvkvælstof og ilt. I sin rene form ved stuetemperatur og i atmosfærisk tryk optræder stoffet som gennemsigtige eller hvide krystaller.

Sølvnitrat bruges i fotografiske film og i fremstillingen af farvestoffer. Desuden udgør det “kilden” til sølv ved forsølvning (herunder forsølvning af glasplader som derved bliver til spejle).

Sundhed og sygdom

Sølvnitrat er giftigt ved indtagelse eller inhalation. Ved kontakt med hud kan stoffet skabe brune misfarvninger, som gradvist bliver sorte. Disse misfarvninger kan ikke vaskes eller på anden måde fjernes – har man først fået dem, må man vente på at huden slides udefra, og ny, “pletfri” hud skabes indefra.

Opløsninger med lave koncentrationer (f.eks. 1 %) af sølvnitrat virker antiseptisk, og har tidligere været anvendt som øjendråber på nyfødte.

Vinsyre

frederiksen link

vinsyre, dihydroxybutandisyredihydroxyravsyre, C4H6O6, farveløst, krystallinsk stof, der er letopløseligt i vand. Vinsyre er meget udbredt i naturen, både frit og som salte. Under vingæring udskilles det sure kaliumsalt vinsten, der er udgangspunkt for den industrielle fremstilling af vinsyre. Kaliumsaltet omdannes til calciumsaltet, som derpå dekomponeres med svovlsyre.

Den naturlige vinsyre er optisk højredrejende, men der findes også en venstredrejende form (jf. isomeri). Den racemiske blanding af disse, kaldet druesyre, er optisk neutral. Endelig er isomeren mesovinsyre også optisk neutral. Louis Pasteurs studier af vinsyreisomerer lagde i 1848 grunden til den moderne stereokemi. Vinsyreanvendes som smagsforstærker og antioxidant i levnedsmiddelindustrien.

Chemistry and Art: Cyanotypes and Van Dyke Prints

[from William Crawford, The Keepers of Light, p.163-165, 177-180 and Catharine Reeve and Marilyn Sward, The New Photography, p 55-63]

Cyanotypes:

The cyanotype process was invented in 1842 by Sir John Herschel, after he had first discovered the photosensitivity of ferric (iron +3) salts. In this process, a suitable (both chemically and physically) sheet of paper is made sensitive to high energy ultra violet (UV) light by coating it with a solution of ferric ammonium citrate and potassium ferricyanide. Exposure to UV light reduces a portion of the ferric (Fe+3) salt to the ferrous (Fe+2) state, and a portion of the ferricyanide (Fe+3 in Fe(CN)63-) to ferrocyanide (Fe+2 in Fe(CN)64-), resulting in the formation of a pale yellow-blue image consisting of ferrous ferrocyanide. Washing removes the soluble, unreduced (unexposed) salts, leaving behind a deep blue and white image. The image intensifies upon drying as ferrous ferrocyanide is slowly oxidized to a deep blue color that results from ferric ferrocyanide. The oxidation can be hastened by treating the image in an oxidizing bath of either hydrogen peroxide or potassium dichromate.

Procedure

Prepare stock solutions-

NB: prepare these solutions at least 24 hours before coating paper. Label bottles with dilution ratios, batch numbers and names of chemicals, and the date. Store both solutions in air-tight brown bottles.

solution A:

distilled water at ~21 °C 100 ml (50 ml)

Ferric ammonium citrate (green) 20 g (10 g)

solution B:

distilled water at ~21 °C 100 ml (50 ml)

Potassium ferricyanide 8 g ( 4 g)

A Note on the paper base

The following properties in the paper contribute towards good image resolution:

a smooth ‘hot pressed’ (HP) surface, unless you deliberately want to produce a print on highly textured paper;

a high cotton or alpha-cellulose content;

an internal sizing agent, ideally with a pH of 7-7.5;

there should be an absence of alkaline buffering agents;

good wet strength, hence the heavier weights of paper are more suitable.

All papers have a ‘felt’ or ‘blanket’ side and a ‘wire side. The former generally has a more random texture and has a less intrusive texture.

It should be noted that paper is a chemical entity in its own right. Each type of paper will react in a different manner with the sensitizer – and at times results can also vary from batch to batch.

Sensitize and expose the paper- work in tungsten light only, not fluorescent or daylight.

1. Paper should be cut so that there is a margin of at least 20 to 30 mm around the area to be coated. This allows for handling.

2. Make guide marks delineating the area to be coated on the sheet of paper. These marks should be lightly penciled in and can be best located by using a cardboard template that corresponds to the size of your negative. Write a print serial number on the sheet thus: [your initials].n – e.g. PM.1

3. Mix the following amounts from your ‘stock’ solutions (which should be at room temperature, 18-22 °C) in a 10 ml flask:

The total volume of sensitizer depends on the negative size, the type of paper, and absolute humidity.

There should be enough sensitizer to make 3-5 passes with the coating rod. Adjust as necessary while keeping the 1:1 ratio of sol.A to sol.B

solution A 0.2 ml

solution B 0.2 ml

Use a separate syringe for each solution (label them). After dispensing the solutions into the 10 ml flask, mix thoroughly by passing the liquid in and out of a syringe two or three times. Use the syringe to pick up this sensitizer solution.

4. Tape the marked paper onto a sheet of glass. Arrange glass coating rod (make sure it is free of any dust or grease), blotting paper, and loaded syringe nearby. Clean the paper surface with a blower.

5. Coating should be done at a room temperature of between 18 and 22 °C and a RH of around 75%. (If conditions are too cold or dry, surface crystallization will occur, and too high an ambient temperature or RH may cause the solutions to penetrate too deeply into the paper). Gently eject solution from the syringe along the top of the coating area. Promptly pick up the spreader and place it on the paper just above the liquid line. Draw the rod into the solution, pause briefly (about a second), allowing the fluid to distribute itself evenly along the length of the rod, and then smoothly pull the spreader down the length of the area to be coated. The surface may look blotchy at this stage, but it will even out in the next few moments. One ‘pass’ for a 10×15 cm area will take about 3 to 5 seconds. Apply only a slight pressure, otherwise the paper surface will get abraded. At the bottom of the first pass, ‘hop’ the spreader over the line of solution and smoothly push it back up to the top of the sheet, thus repeating the process, but in the opposite direction. Make 3 to 5 passes over the paper in this way. It is best to stop before all the solution has been absorbed into the paper. The excess is then soaked up with a strip of blotting paper.

5.5 An alternative method is to use a brush to apply the solution.

6. Place paper in drier for 10 minutes. Drier temperature should be between 35-40 °C (95-105 F).

7. As soon as drying is complete, place paper in contact with negative (sensitized surface to emulsion) in printing frame and expose to UV light source. Printing times will vary according to negative density. The image is partly formed during the exposure and the construction of the printing frame allows you to examine the print by opening one half without disturbing the registration of the negative to the print. Make sure that this ‘inspection’ is carried out in an area shielded from the UV source, otherwise the print will be fogged.

Caution: do not look into UV sources while they are on.

8. Clear print in a water bath for about 1 minute. Wash in running water for 5-10 minutes, or until highlight (white) areas in print have cleared.

9. Hang up to dry.

Van Dyke Prints:

For Lab

g

ml

ml

g

A

Ferric Ammonium citrate

18

water

50

B

tartaric acid

3

water

50

C

silver nitrate

6

water

200

Total volume

300

Mix each solution separately.

Combine solutions A and B and slowly add solution C, stirring constantly.

5% thiosulfate

MW Na2S2O3.5H2O

= 248.18

The sensitizing solution is already mixed and prepared. Follow essentially the same steps as for the Cyanotypes.

There is one additional fixing step, after the developing/initial washing for about one minute. Fix for five minutes in a 5% thiosulfate bath. Then wash.

Requirements:

1. Using the negative or other high contrast object (e.g., lace doily or lace ornament; dried flowers and leaves also make interesting prints) and paper supplied make 3 cyanotypes and 3 Van Dyke prints; the first print might should be a test strip to see the effect of exposure time.

2. For each process make changes in one of the variables so that you can study the effect of that variable on the process.

Factors

Controls

Sunlight if shining

Application method

A (single) negative or pseudonegative

Use a 21-step wedge

Variables

Paper – several kinds

Exposure time

# drops

# coatings

Filters

3. Turn in all prints, labeled. Either attach to lab report pages or (and perhaps better) put them in an envelope so I can spread them out.

Enhancements:

1. Choose the three or four areas (one dark, one white, one or two grays) that you used with your best black and white print -and mark these same locations on your best cyanotype and best Van Dyke print.

Use the colorimeter to measure the L*a*b* values (and others if you are interested).

Compare and comment on the results, i.e., compare L* values among types and a* and b* (and/or chroma and hue) within types.

Be sure to check calibration at the start and again at the end. A graph/chart of L*, a*, and b* values might be good.(That doesn’t mean to recalibrate at the end! – rather check that the calibration is still correct.). Record those two points on your Excel sheet too.

2. Compare the same 3 or 4 areas on your negative. (You may have done this last week with the silver prints).

3. Weather permitting, do at least one exposure using the sunlight rather than the UV lamps or vice versa.

4. Use handmade paper – sizing is an interesting variable.

5. For at least some of your colorimeter readings, do duplicate readings.

Printing data:

A table something like the following should be used for each sample:

Print #

Paper type

ml solution A

ml solution B

# of passes for coating

Room temperature

Sizing

Exposure time

Rinsing time

Drying conditions

Colorimeter data

Chemistry and Art: Cyanotypes and Van Dyke Prints.