g'day all
i've been experimenting with VDB and cyanotype printing using inkjet negs

i have encountered several problems, OHP materials are expensive, not readily available and my printer ruins the surface during the printing

so, paper negs -
are they viable?

can i somehow reduce the extremely long exposure times? (3 hours for the attached image)

ideas?

suggestions?

the attached image was originally captured with a 10Mp Canon 400D digital SLR, the file was converted to B&W and adjusted using a simple curve in PS8 then output to a thin coated inkjet paper which was then contact printed to VDB on gelatin sized paper

re VDB-
size or not?

one or two coats of emulsion?

how determine enough exposure?

what causes bronzing?

how increase contrast?

i have seen paper negatives coated with wax used for making bromoil prints, so it may be possible.

paper type will determine sizing, i have never sized paper for my vdb

we have used both types of coating in our workshops, and whether or not you use one or two coats is a personal opinon.

you need to do a step wedge to determine exposure times

there are several methods that can be used to increase contrast, the one that works best for our classes is to place about 10 drops of 10% solution of potassium dicromatic in a tray with about 2 liters of water before washing .

some people put the dichromate in the coating solution. we tried that way but find the bath version more effect.

g'day all
i've been experimenting with VDB and cyanotype printing using inkjet negs

i have encountered several problems, OHP materials are expensive, not readily available and my printer ruins the surface during the printing

so, paper negs -
are they viable?

can i somehow reduce the extremely long exposure times? (3 hours for the attached image)

ideas?

suggestions?

the attached image was originally captured with a 10Mp Canon 400D digital SLR, the file was converted to B&W and adjusted using a simple curve in PS8 then output to a thin coated inkjet paper which was then contact printed to VDB on gelatin sized paper

re VDB-
size or not?

one or two coats of emulsion?

how determine enough exposure?

what causes bronzing?

how increase contrast?Hi Ray,

Here are my thoughts about the questions you asked.

1) Size or not

I never size paper for VDB (as a matter of fact I only size paper for gum printing). What paper are you using to print on? There are several good papers you can use to print VDB. A very inexpensive but good paper is the new Weston Diploma Parchment.
http://www.crane.com/business/westonpapers/platinumpalladium.aspx

2) one or two coats of emulsion

I always double coat VDB, however double coating will print slower but give better DMAX, IMO.

3) how determine enough exposure

With digital negatives you need to give the coated paper the minimum amount of exposure to get DMAX when printing the substrate

4) what causes bronzing?

Long exposures can cause bronzing or excessive moisture content in the emulsion

5) suggestions?

Inkjet Paper will be very opaque to UV light causing potentially extreme exposures. You should plan on using some kind of transparency material.

You will need to develop a process adjustment curve to allow proper rendering of tonal relationships when printing with digital negatives.


6) my printer ruins the surface during the printing

What kind of printer are you using?

There is a lot more we could address here but this should get the discussion going.

Don Bryant

you need to do a step wedge to determine exposure times


Printing a step wedge will tell you what the basic coated paper speed is but you will need to allow for the density of base of the digital negative substrate to determine the minimum exposure time.

You can do this by covering half of the step wedge with the substrate and printing until the density of the first step of the covered part of the step wedge matches the DMAX of the uncovered step wedge.



there are several methods that can be used to increase contrast, the one that works best for our classes is to place about 10 drops of 10% solution of potassium dicromatic in a tray with about 2 liters of water before washing .


I've never gotten potassium dichromate to affect contrast but I've only used 5%, I'll have to try the 10%.

Which other methods have you used to increase contrast?

Don

just dawned on me, that should be about 10 drops to 500 ml of water, sorry, tired brain tonight lol

don, we tried various amounts of the 10% solution to the sensitizing solution but not with much success, however adding to the first wash bath was successful

the dmax of the weston paper is also better, at least with my negatives and in my envrironment.

just dawned on me, that should be about 10 drops to 500 ml of water, sorry, tired brain tonight lol

don, we tried various amounts of the 10% solution to the sensitizing solution but not with much success, however adding to the first wash bath was successful



Okay I'll try that.

Don

g'day all
i've been experimenting with VDB and cyanotype printing using inkjet negs

i have encountered several problems, OHP materials are expensive, not readily available and my printer ruins the surface during the printing

so, paper negs -
are they viable?

can i somehow reduce the extremely long exposure times? (3 hours for the attached image)

ideas?

suggestions?

the attached image was originally captured with a 10Mp Canon 400D digital SLR, the file was converted to B&W and adjusted using a simple curve in PS8 then output to a thin coated inkjet paper which was then contact printed to VDB on gelatin sized paper

re VDB-
size or not?

one or two coats of emulsion?

how determine enough exposure?

what causes bronzing?

how increase contrast?

Not to make light of it but you have quite a list of problems here and not enough specifics to answer all your questions.

Paper negs are viable. You might want to do a Google search to find more information about them. I have made pinhole negs on paper that I then printed to VDB. I have not printed digital to paper and printed though. A couple of things to keep in mind. Some papers have very low UV transmission and VDB is a UV process. You can increase the transparancy of paper with various coatings, waxes, oils, etc. - I have done this for silver prints but not for any UV process so I don't know if it helps. I have read that it works for gum printers, another UV process, so I expect it will for VDB.

Two things about your printer -- You didn't say what you are using but some printers do mark OHP materials and, depending on the printer, there may de work arounds for the problem. The second thing is that some ink sets have low UV transmission and the choice of black or color ink printing can also influence the way your neg will print. There is a lot of information on this online.

You didn't mention what your light source is. It would help to know.

Three hours is an incredably long printing time. I print in a homemade 7 BL tube light box and I think the longest I have ever printed a dense camera neg was about 20 minutes. My digital negs print quicker than that.

I do double coat - It helps with D-max but, since most of my camera negs don't have the density required for VDB, I usually scan them and make digital negs for VDB. Once you get a good curve for them, it goes pretty smoothly. If you haven't run across PDN or Charthrob, do a search for them.

There are a number of things that can cause bronzing. One of them is over exposure. With a 3 hour exposure, this may well be your problem.

As to contrast, with a digital neg you control it with the curve you apply.

Dan

g'day all
great info, i need to re-read and consider it all, thank you

another question re: VDB - i'm having problems being sure that the emulsion is dry enough, some advise printing bone dry, some advise printing when very slightly damp, i've already ruined 2 LF negs to 'very slightly damp', which seemed to not give any better result (just the ruin of 2 negs)

so - can VDB coating be dried with warm air?

thnx
Ray

printing damp, surely someone is kidding.

you can dry the coating with warm air. we let the paper begin to dry on it's own and then finish it in a film dryer at a very low temperature.

you could use a hair dryer but dry from the back side of the paper (non coated side).

i missed something , a 3 hour exposure. oops just went back to re-read and discovered your point about that length of expsoure,

expsoure in our sitituation runs for 8 to 30 minutes, using a UV book.

g'day all
great info, i need to re-read and consider it all, thank you

another question re: VDB - i'm having problems being sure that the emulsion is dry enough, some advise printing bone dry, some advise printing when very slightly damp, i've already ruined 2 LF negs to 'very slightly damp', which seemed to not give any better result (just the ruin of 2 negs)

so - can VDB coating be dried with warm air?

thnx
Ray
Ray,

Damp is not good. You can allow the paper to air dry with a fan blowing on it. Low heat with a hair dryer will also work, just don't over do the heat.

Don

g'day all

another question

can cyanotype coating be dried with warm air?

g'day all
can cyanotype coating be dried with warm air?
I dry everything (gum, pt/pd, van dyke, cyanotype) with slightly warm (maybe 120 deg F) air: muffing fan and hot plate heating element, diode to cut the power down.

g'day all
i've been experimenting with VDB and cyanotype printing using inkjet negs

i have encountered several problems, OHP materials are expensive,
Not relative to even a single print sale.


not readily available

Where are you?

and my printer ruins the surface during the printing

What printer? There are ways around "ruined" surfaces on just about any medium.


so, paper negs -
are they viable?

Define "viable". Do you want the shortest exposure times, the best detail, lack of texture from the paper, or do you want to save a small amount of money?


can i somehow reduce the extremely long exposure times? (3 hours for the attached image)

Three hours, and it's still underexposed.

What is your light source? The paper negative works best when wet. Ann mentioned wax, that's a step in the right direction. The best coating will match the index of refraction of the fibers in the paper, and turn it pretty much clear. Oil, wax, and water are common. All three of them will bring a cyanotype process to a grinding halt. If wax or oil transfer to your coated paper, they will mask development and clearing. Water, obviously, isn't going to work on a medium that needs to be dry.

That's where Saran wrap comes in. It's thin enough to not bolux your printing, and will protect the image. Tape the paper down. Tape the saran wrap down over the paper. Wet squeegee the paper negative face down onto the saran wrap.The hard part is getting the contact printing glass onto the top of the wet negative without bubbles. The most helpful thing is to mount the print so that it bows up in the middle, and the glass so it bows down, and come down very straight.

You'll get sharper images if you continually turn the stack so that it faces directly into the sun.

Good luck.

Ray,

You’ve got a lot of questions, and most have been handled or at least suggestions made about them from other forum members. However, I’d also like to add my comments.


Negative substrate – You indicate too expensive, so you’d like to use paper. There are other alternatives. BTW, you didn’t state what transparency material you tried to use, nor what printer you were using. This is important information. The accepted best transparency material is Pictorico OHP. Locally a number of alternative process printers are using Agfa CopyJet because it is available locally. There is currently no distributor/reseller of Pictorico OHP in Australia, so you have to buy it directly from Pictorico (Mitshubishi) or someone else like Bostick&Sullivan. My preference, on a per sheet cost basis is Pictorico. A 20 sheet box from Pictorico is $19.95 USD, while a 100 sheet box of CopyJet is over $200 AUD. Work the math out, and even with the exchange rate and shipping costs, Pictorico is more cost effective (not by much, but a savings none the less). And I prefer the Pictorico because it is a bit thicker than CopyJet and reduces paper feed problems.

I mentioned alternatives – well I have attended a number of alternative processes workshops in Australia (primarily in Melbourne) and some used Laser Printers or Copiers. For these two alternatives you’ve got to find a printing service bureau that will listen.


Long exposure times – If you mean using paper negatives, that would be right, as without waxing or oiling, the paper is just not translucent enough. The paper may be blocking UV. If I recall from one of your previous posts, you are using a 2-tube BL light? That’s a bit weak. I built a 10-tube unit for about $400 including the tubes. Distance from tube to contact printing frame in about 5 inches. My exposures with film using Ziatype are around 6 12 minutes. Using Pictorico OHP for Ziatype exposure times are 3-6 minutes. If you wax/oil the paper, as Wiz stated, you need to use some clear protective material between the negative and the sensitized paper. My suggestion would be thin Acetate readily available from most art stores. You live in Maitland, so there must be one decent art store in Newcastle.


Sizing – None of us in the Melbourne circle use sizing for Cyanotype or VDB. Our favorite paper is Stonehenge Cream, out of the box readily available from good art stores, and it doesn’t need sizing. Heck we even used inkjet paper, usually Hahnemuhle Photo Rag. That paper works really well with combination processes, like Cyanotype or VDB over inkjet.


Number of Coats – That will be dependent on a lot of variables. Wynn White always double coats. He has a VDB guide at -> http://www.alternativephotography.com/process_vandyke.html The examples of his work are exceptional, Pt/Pd like.


Marks on your print material whether paper or transparency, but I suspect mostly transparency, are most likely caused by the printer’s pizza wheels. The problem is relative to the printer model, mostly Epson. I have the problem occasionally on my Epson 1290, but it doesn’t happen much on my Epson R2400. There is a good article about this at -> http://www.inkjetart.com/pizza/


Increase contrast – Before you can delve into contrast control through whatever means you really need to get density right. I believe one of the other forum members who replied talked about this (Don Bryant). It is important to determine the minimum exposure time for your workflow, process and paper combination. What you have shown is an underexposed print that may end up having the contrast you envisage with the right exposure. If you were using a paper negative and your 2 bulb UV light, then I suggest at least exposing by the Sun to see if that helps. Perhaps try 6 hours with your set up? Remember, the early photographers didn’t have access to a UV light box, they used the Sun.



You really must buy or build a step wedge (a minimum 21 steps as a start but going up to 50 and 100 will tell you more). It’s absolutely necessary to evaluate your process variables through step wedges early on to tell what your process is doing! You also need them to build your own personal correction curve for your negatives.

thank you Gene, an excellent, well written and thoughtful post, lots to consider

Ray