Photogravure on rubber to make photographic stamps

[holmburgers]

Howdy,

I'm thinking about the possibility of making photographic stamps, and ultimately, color separation stamps. It could be like a poor man's version of dye-transfer printing.

The steps would be similar to typical photogravure except that instead of etching a copper plate you'd have to find a suitable chemical to "etch" rubber.

I know nothing in this realm of chemistry, but does anything come to mind that might be suitable? What dissolves rubber?

Sure this is a hare-brained idea, so feel free to crush my dreams if there's cause to do so, but I'd greatly appreciate any constructive comments.

Thanks,

Chris 'holmburgers' H.

 

[alexhill]

Thats interesting, can't wait to hear more

 

[richard ide]

Rubber stamps are made by impressing with heat and pressure a rubber sheet into a mold which is the reverse of what you want. There must be a rubber stamp manufacturer close to you which could give you a better description of the process.

 

[holmburgers]

Well I understand how stamps are made, but that's not exactly what I'm interested in doing. I'm proposing a method to produce them thru photographic means. However, perhaps heat would have to play a role. (acid maybe?)

Like in photogravure, you'll apply the image to the rubber either on a gelatin tissue, gum emulsion or something like this, and then develop with whatever chemical will eat away the rubber where there is less of the gum/gelatin/bitumen (I have no idea really), etcetera etcetera.

Alexhill.... I can't wait to hear more myself

 

[grahamp]

I know a lot of people who hand-carve rubber stamps, as opposed to using the vulcanized commercial offerings. photogravure implies tones, not solid prints, which is what stamping produces. I have seen some incredible tonality done by approximating a half-tone effect by carving, but it cannot be too fine or the ink blocks the detail.

A process clear/black image and a UV curing medium might work. If you can find a way to do that, then adjusting the image (posterize to 2-3 levels) would give you a set of stamps for registration printing. That's possible by hand carving, but a lot of work.

 

[Schlapp]

Isn't there a light sensitive film one can get? Not sure how one would 'etch' the rubber tho

 

[holmburgers]

It seems like the light sensitive part would be easy, just need what grahamp said, a "UV curing medium". I don't know much, but would gum bichromate (minus pigment) be suitable? Admittedly, I don't know enough to be throwing around terms, but I know enough to say that it would require a emulsion that hardens in proportion to the exposure it receives. Then you could wash/develop it away, exposing the rubber to allow the etchant access.

As for etching rubber, I have no idea, but it seems like any number of things would eventually eat thru rubber. However, if a chemical/acid can eat thru rubber, will there be a 'UV curing medium' that can withstand it? That is the key question I s'pose.

 

[Whiteymorange]

Boxcar Press sells photo sensitive plates that are plastic-backed or steel-backed polymer printing plates. If you expose them through a transparent positive, you can ink them, wipe them and print them as etchings (photogravure.) If you expose them through a negative (and a half tone screen) they can be inked with a roller to print the raised image. Either way you will get a positive. The thickness of the polymer and the detail you get are functions of many different things, but it's a pretty straightforward process, if not a simple one. Four plates, exposed through negative color separations and printed with Black, Cyan, Magenta and Yellow, will give you a color image. Voila! You will have re-invented the printing method used by print shops all over the world for much of the 20th century.

 

[rmolson]

photo gravure and rubber plates

I wonder what you are trying to create.If it is true gravure then you have chosen the technically more difficult of all the graphic arts printing processes. Letter press plates had raised metal images that accepted ink. Lithography were stones and later metal plates the accepted ink on the image and the image was transferred by contact the paper Offset lithography the metal plate accepted ink in the image area only the non image area accepted water ( actually a very specific solution called a fountain solution) which was then transferred to blanket usually a rubber type material which then transferred the image to the printing paper .Gravure also called intaglio printing ,the image was receded in the metal call cells and the paper pressed in to it to .Roto gravure were gravure plates spun at high speed and the ink literally thrown onto the paper Roto gravure required both a halftone image and a continuous tone image to get the correct depth in the cell for the ink. It was a highly complicated and specialized operation.. Until web presses were introduced it was the best way to do high speed printing .When webs were introduced they were capable of 70,000 impressions per hour. The average offset press normally peaked out around 10 to 15,000 iph.
Rubber printing plates used letterpress type plates to form the image ,and as I remember it required an intermediate step to get a reverse depth .Perhaps a film positive was used to create the engraving and the rubber plate pressed directly from that .It was a long time ago that I worked in it .
Good luck with your project.

 

[holmburgers]

whitey, thanks for the reply. Your description is encouraging and indeed I found these photopolymer plates on the web after my last post. So, is the half tone screen the key to getting continuous tone? I read the autobiography of F.E. Ives who invented/pioneered the photogravure process (IIRC) and he talked extensively about half tone screens. Hmmm, I think I will have to give this a try!

rmolson, thank you as well for the overview. I guess I said 'photogravure' for lack of a better understanding on my part of the different processes, but basically I'm interested in this type of printing but looking for a simplified/affordable method. Ultimately, I just want to get into tri-color printing.

I'm also toying with the idea of using etch-at-home copper circuit boards. Normally you draw the circuit with an acid-resist pen and then etch in acid, but perhaps the acid-resist pen could be replaced by this elusive UV curing medium Just a thought....

 

[richard ide]

You can buy circuit board presensitized with a coating similar to silk screen photo emulsion. IIRC you wash the sheet after exposure to remove unexposed resist and then use Ferric Chloride to remove the copper where not required. Coating would work with sunlight exposures.

 

[Mick Fagan]

Interesting thread.

A half tone, or screen ruling picture, is one that simulates a continuous tone picture (a photograph)

If you look with a loupe at a printed with ink, good quality magazine colour or B&W picture, you will see various coloured and various shaped dots.

Most magazine printing would be around 150# (# denotes the word screen) and a higher quality (mostly) version may go as high as 300#.

I would suggest a screen ruling around 40# to about 60# could be suitable and achievable in a home environment using very basic equipment.

This is usually done with a four colour process CMYK (Cyan, Magenta, Yellow and Black).

The link Whitey gave brought back memories of proofing with originally zinc acid etched plates, then magnesium water etched plates sitting on the form platten, just like that orange polymer plate.

That printer looks to be motor driven, you may find quite a few that are hand driven, these are excellent and quite cheap, or at least they were once.

Regarding rubber, well I'm a rubber stamp manufacturer and generally the stamp (or marking in the USA) industry uses rubber with a shore hardness around 35-40. Polymer plates would be a better bet as their printing plate shore hardness, is normally much higher.

You can purchase liquid polymer from USA firms and their range of product is very good and may be useful in your search:- http://mrmarking.com/polymer.html

I have used these products, mainly the i40 (shore hardness 40) and seen the i95 which is incredibly hard.

With these processes you can manufacture very hard plates with total control over almost anything, including overall plate thickness.

Essentially you will need a vacuum of some sort to enable enough suck to hold your negative and/or positive down. Then you need some UV source.

If you scroll down you will also see a daylight negative system. This is brilliant, you need a sheet of glass to sit the exposed negative on, spray the activator on, wait about 45 seconds, then wipe off and or quickly rinse under cold water.

I could go on, but a ring around smaller rubber stamp shops in your locale, may unearth a myriad of possibilities for you.

Mick.

 

[OldBikerPete]

I had used a photographic process for many years to produce printed circuit boards. The process may possibly be adapted to your purposes.
One produces either a positive or negative high-contrast transparency of the pattern you wish to produce.
One lays this hard up against a plolymer board which has been plated with a few thousands of an inch of copper and then 'Kodak photoresist' (KPR) or a similar product whch may be either positive or negative working.
One then exposes this to UV light until those portions of the resist below the transparent part of the transparency undergoes a chemical change - softening if positive working or hardening if negative-working (like KPR). The board is then washed with a solvent which preferentially removes the softer resist followed by a chemical etch (ferric chloride in the case of copper circuit boards) which dissolves away the copper not protected by hard photoresist. Drill appropriately and you have a circuit board.

Printing plates for half-tones are made by a very similar process excepting that the areas not solid black or white in the original image are represented on the high-contrast transparency by a 'grid' of dots of different densities as has been discussed above. If your original image is digital then many programs are capable of transforming a greyscale image to a gridded litho-film image. How one does this without computer help, I don't know.
My brother-in-law is a printer who makes his own plates, so I wiill ask.

 

[holmburgers]

So if these polymer plates usually have a much higher shore hardness, does this make them less suitable for "hand" pressing? There's no way I can afford a printing press or anything like that, so I was hoping to do this all by hand, maybe a clamp or something at the most. Then again.... how cheap is "quite cheap"?

Having just learned about liquid photo-polymer and PP in general, I can't yet fathom the possibilities, but they seem endless!

I am curious to know more about halftone screens. Don't they have to go between the image and the plate? How would this work w/ contact printing? This is totally new to me, so forgive my ignorance.

Thanks for the input on PCB's as well guys!

 

[Loris Medici]

Just lay the paper on the plate and use a hard rubber roller to transfer the ink. To my knowing, you won't be able to get continuous tone with relief printing BTW...

 

[holmburgers]

Well not continuous tone, but how about acceptable half-tone?

 

[Loris Medici]

To my knowing relief printing (see woodcut also) is a monotone printing method, you can only print solid areas of color (ridges), OR no color (grooves). Halftones are possible only with intaglio aquatint printing (w/ trad. acid etched - through gelatin carbon tissue - copper/zinc/steel plates, or photopolymer plates) which absolutely necessitates an expensive etching press.

I think you should read some books about printmaking and photogravures beforehand, in order to learn about the principles...

Regards,
Loris.

 

[holmburgers]

Loris Medici, it seems like what you're saying and what others have said in this thread are at odds. How do you respond to what Whiteymorange said about using a halftone screen?

In my mind, it seems reasonable to assume that if you use a half-tone screen to create the relief, then you will get very tiny areas of monotone, that is, half-tones.

That being said, I do agree with you, I need to learn more about printmaking.

 

[alexhill]

To my knowing relief printing (see woodcut also) is a monotone printing method, you can only print solid areas of color (ridges), OR no color (grooves). Halftones are possible only with intaglio aquatint printing (w/ trad. acid etched - through gelatin carbon tissue - copper/zinc/steel plates, or photopolymer plates) which absolutely necessitates an expensive etching press.

I think you should read some books about printmaking and photogravures beforehand, in order to learn about the principles...

Regards,
Loris.

Your statements match my experience of print making. I have read a bit on photogravure and tried (failing miserable with both a presensitized polymer and traditional carbon tissue) You must use a mezzotint screen between your continuous tone negative and sensitized plate.

Also the expensive printing press isn't exactly right (just mostly ). I've seen videos of artists using steam rollers to make massive prints. Making your own photogravure IS possible in a home set up with very basic supplies... But for your own sanity- take a class.

 

[Whiteymorange]

whitey, thanks for the reply. Your description is encouraging and indeed I found these photopolymer plates on the web after my last post. So, is the half tone screen the key to getting continuous tone? I read the autobiography of F.E. Ives who invented/pioneered the photogravure process (IIRC) and he talked extensively about half tone screens. Hmmm, I think I will have to give this a try!

If you expose a plate through the positive alone, and here I speak of gravure printing, you will get uneven ink distribution on the plate. This is equivalent to "open bite" in etching. What you need to get an even tone is a scattering of small, ridged dots across the area which each catch and retain some of the ink. I use an aquatint screen from Dan Welden at solarplate.com. Halftone screens serve the same purpose. The screen I have is digitally printed with a stochastic pattern, not a rigid series of dots-per-inch, and leaves a far less visible trail in the final print.

Fine halftone screen can be used with a good press and careful inking methods, but the previous posters are correct in that they are too fussy for homemade work. A rougher screen will leave a visible pattern, but may be better to work with in making the photo positive through which you expose your plate. Think Litho film - this is what it was invented for. Without any translation of gray areas into a dot pattern, you have only the edges of broad areas to differentiate between your colors. Simple silkscreen prints are the best example i can think of to describe this. The polymer plates are perfectly capable of resolving dot patterns that will allow you to print color separation plates into a pleasing full-color image, but yes, you will really should have access to a press. They are often available through extension programs at universities that have art classes or in group studios where they may be rentable by the hour. Or find a friend with a press. I'm spoiled in that I live in, or near, a city with all of these things, but many of my prints have been made on a press that a friend has lent me- a cheap Dick Blick etching press sold to allow portable printmaking for art fairs, etc.

At least one of the types of plate available through Boxcar is used as a casting mold for rubber stamps. This may serve your original purpose. Check with them about how that works- they're nice people

 

[holmburgers]

I did some searching and you're right, my local Arts Center has a printing program and not to mention the University of Kansas here in Lawrence. So perhaps I can get access to a press down the road.

However, I probably need to learn more about printing in general before going much further. What are some of the seminal books about print making? Something that explains all the different methods, the equipment, the terminology, historical considerations, etc. Any recommendations?

In the meantime, I think I could play around with photopolymer and have a ball! Is exposing via sunlight too finicky? Perhaps I could build a cheap UV box, there are lots of tutorials online.

 

[alexhill]

I'd go with the sunlight personally. I tried the tutorials and materials from cape fear press which was a good starting point. Perhaps I will try again in the future. If anyone is in NH, the institute of art in Manchester has a fantastic photogravure book called Egypt in their special collections. Absolute stunning.

 

[Whiteymorange]

Unfortunately, I have no books to suggest, but there are many out there worth having. I did a lot of printmaking in college and then I took a workshop at a local museum in printmaking using photographic plates. I use a "facial tanning lamp" bought from ebay for $25 and installed in a very simple wooden box which gives me about 5" of space above the plate glass that holds down my positive and printing plate. Exposures are in the 40 second range and then about 100 seconds with the stochastic screen. There is a hardening exposure necessary after the wash, for which I use sunlight whenever possible, but I like the control that an electric light source gives me for initial exposure - sunlight can vary greatly from time to time and I din't trust my light meter enough to keep risking plates. At about $10 a shot for an 8x10 exposure, I need to plan a bit more carefully.

Look for a local workshop in printmaking. You'll learn a lot from the other printmakers as well as from the teacher and have access to the press a the same time.

 

[Loris Medici]

• The Printmaking Bible: The Complete Guide to Materials and Techniques
• Copper Plate Photogravure: Demystifying the Process

There are fine books around about photopolymer gravure too. (See books from European / Scandinavian writers...)

In any case you'll need access to (1) a reliable point lightsource with a vacuum frame (= platemaker) and (2) a fine etching press to make high quality photogravure prints... (Plus, lots of work / practice - for instance, inking is an art itself...)