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Nontoxic Printmaking, Safe Painting & Printed Art

Waterbased Silkscreen Printing                 CONTENT  |  SEARCH









silkscreen installations (F.K.), Gallery Daeppen, Basel















The DVD 'Man At Work' gives a very informative overview of Robert Rauschenbergs life-time achievement. 20 minutes are entirely devoted to the making of the historic silkscreen installation 'The 1/4 mile Piece', which was printed in situ on a wide variety of substrates such as plastics, canvas, and metal using water based silkscreen methodology. The DVD was narrated by Sean Barrett and directed by Chris Granlund.












Waterbased screen printing is a well researched

and sophisticated graphic medium


It lends itself particularly well to art projects

that cross media boundaries.

 
Despite its long Eastern history,

in the West silkscreen is more associated with Pop,


appropriation and the use of photography

and reproduction in art making,


than with printing traditions and conventions

dating back hundreds of years.


This is reflected in the widespread appeal:

silkscreen is a refined method of art printing,

yet it is very easy to use, safe,

inexpensive, and very accessible.



Silkscreen offers the broadest spectrum of printing applications, and it facilitates printing on all kinds of paper as well as on a wide variety of unusual substrates, such as plastics, wood, or metal. The medium seamlessly combines the expressive vocabulary of the artist’s hand made gesture with the world of the reproduced image, and full color printing. Three decades ago the print quality of the water based process was not always on a par with the (much more toxic) oil based process. These obstacles have been overcome through improvements in the water based inks, pigments, dyes, and mediums. Even the master of Pop Robert Rauschenberg used the water based process in the creation of his recent silkscreened assemblages, such as his monumental ‘1/4 mile Piece’ documented in ‘Man at Work’.


Following some very straightforward instructions almost anybody can set up a safe and simple screenprinting facility in their garage or spare bedroom. Many successful printing firms and artist print studios were started this way - Andy Warhol's factory was one of them. With the addition of an etching press the range of possibilities can easily be extended to include the new Intaglio Type medium as well, and many workshops now have UV or halogen exposure systems that cater for both photopolymer based processes.






'tulip 2', 2010, Michael Hitchens, based in Manchester, England. The majority of his work presently revolves around water-based screen printing using digital artwork and CMYK printing.







Joe Lindsey
Silkscreen and Digital Print
Columbia College Chicago
Academic Print Studio
2007















Nintendo Half Tube
Silkscreen and Digital Print
Installation on wooden Half Tube
Chester University


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Reuels.com has an excellent set of introductory silkscreen instructions on their web site. This illustrated guide is so straightforward, it can help anyone set up and master their own photo-emulsion based silkscreen process, using basic yet very serviceable and inexpensive practical solutions. A lifeline for many start up silkscreen artists and art students.



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Silkscreen Inks



Printing with acrylics on a variety of substrates: vinyl saddles (left)
'Blind' printed aluminum panels (right)


There are two kinds of acrylic based ink system that are widely used. Premixed ready made inks such as Speedball or Jacquard, and ink systems for self mixing using acrylic paint and a custom silkscreen printing medium (see below).

The following brand of inks is particularly suited for opaque printing on unusual substrates:
Jacquard Professional Screen Printing Inks are stated to be professional quality and permanent on most non-porous surfaces including: fabric, paper, plastic, vinyl, leather, metal and more! These inks break new ground with an appreciably longer open time in the screen in comparison to other water-based products making them perfect for small production runs. They screen beautifully with excellent resolution. Jacquard Professional Screen Printing Inks are particularly well suited for commercial applications and will not wrinkle paper when screening art prints. These inks are archival and lightfast. Cleanup is easy with just soap and water. Fabrics must be heat set for permanence and wash-fastness. Once set, the inks are fully washable and dry-cleanable on all natural and synthetic fabrics. www.jacquardproducts.com

 


ready mixed acrylic silkscreen printing inks: Versatex, Speedball, Jacquard

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Silkscreen Ink mixed from Acrylics
and Printing Medium


Most manufacturers of acrylic artist paints offer a dedicated medium or paste which is mixed with their artist acrylics to obtain a printing ink. Acrylics by themselves are too fast drying and too viscous to make serviceable printing inks. The dedicated silkscreen printing mediums contain thickeners and retarders that make acrylics printable. Most systems have a 50% to 50% recommended ratio between ink and medium to obtain a good ink. In practice, the addition of these mediums has little effect on the luminosity and opacity of the acrylic paint. In essence these systems provide an opportunity to create printed marks on paper using high quality artist paints rather than commercial printing inks, which are often lacking in light fastness and color quality.

For thinner washes and translucency, inks can be thinned through further addition of printing medium, extender base, or water. Although manufacturers recommend staying within their own product lines, the different types of acrylic paint, modifiers and mediums can easily be intermixed by the artist or printer to obtained desired properties. Once you've mixed a batch of ink with a plastic kitchen spatula store it in lidded plastic containers and keep color swatches to be able to identify the correct hues. The acrylic silkscreen ink, once mixed, can be stored for several years without deterioration.

 

50% Acrylic Paint + 50% Printing Medium = Acrylic Screenprinting Ink

 


Rowney System3 Printing Medium   /   Lascaux Silkscreen Paste   /   Golden Silkscreen Medium



 

There is a wide variety of acrylic printing mediums and modifiers that allow for further refinement of the inks, through the addition of gloss medium, thickener, texturing agents, and so on. The range of acrylic paints, ready-made inks, and modifiers available today make it easy to obtain the luminous and highly opaque ink deposits that were once only possible in the oil based process. At the same time, the water-based process also facilitates the opposite to the opaque graphic surfaces of Pop art: delicate wash work, textures, and translucency that is typical of media such as water color and lithography. Two of the pioneers of the water-based method - Roni Henning, and Carol Robertson - demonstrate the medium’s potential for extremely detailed and delicate work in their editioning practice.


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two typically used silkscreen emulsions: Speedball (left), and Ulano (right) and a scoop coater. Make sure you apply a thin even layer, or the image will not reproduce. Diazo emulsions are made up by mixing with an activator. Once activated the emulsion needs to be refrigerated for storage. The manufacturers offer dedicated emulsion removal products, usually based on sodium meta periodate, a safe stripping agent made from an iodine compound. This is also available from chemical wholesale.

 

The water-based process generally involves clean up with soap and water, and there are no significant emissions of harmful fumes - or the need for extraction - in the silkscreen studio. By contrast, to this day the oil based process utilizes a particularly potent cocktail of volatile hydrocarbons (mainly composed of Xylene, Toluol, and Mineral Spirits), both in the inks and for cleaning and thinning. This harsh chemical environment is known for its potential to be particularly harmful to the printer and the artist. There are numerous known cases of neurological disorders, cancer, Asthma, and respiratory illness that are believed to have originated in oil based silkscreen practice.

Problems can be exacerbated by the fact that many printers do not wear respirators while handling and inhaling neurotoxic fumes, and often extraction systems suffer from poor designs (powerful local extraction is the best solution available. Such as: Nederman Gas Cart).
Since the 1960s there has been increasing medical evidence that most petroleum derived solvents are toxic. This has been the basis of various lawsuits brought by afflicted workers (in the US railway industry, for example). Over the past 20 years - and with little publicity - there have also been lawsuits regarding sickness or injury resulting from solvent use at art schools. (See Artmaking and The Law).




the UK firm Natgraph makes excellent UV exposure systems using metal halide light sources. As opposed to other systems these type of top loading machines can handle both photo silkscreens as well as photo-polymer intaglio plates. This saves expense and floor space.



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Transparent Artwork.
The photo silkscreen process requires the use of transparent artwork. Many art schools simply use photocopies that are being oiled with mineral oil - the oiling process is a bit messy, but it works well, is surprisingly reproducible and saves cost. For good quality transparencies today usually larger scale inkjet printers are used to produce transparencies from digital artwork. The dense opacity of the inkjet process is of advantage. The denser (darker and more opaque) a transparency is the better it will perform as a matrix for photo-based printmaking. The output of Laser printers has the tendency to make transparencies that can be somewhat less dense, but even a cheap letter size laser printer can be used to output CMYK layers with the correct dot structures and screen angles directly from Photoshop. (
This is something inkjet printers only do when coupled with expensive RIP software). For projects requiring good blacks and contrast laser transparencies can be printed twice and then the two sheets of acetate are sandwiched together - this yields a much denser copy and results in a better screen or photo-polymer plate. The latest generation digital photo copiers produce outstandingly dense transparencies that are ideal for photo-reprographic printmaking.

There are many ways to draw and paint transparencies directly by hand using black media such as acrylic paint, water proof ink, Sharpies or litho crayons. Normal sheets of acetate will not hold subtle marks and fine detail, until the material has a tooth. There are special silkscreen films such as 'True Grain' that are designed for this purpose. Many printers now use photocopy toner / floor polish / detergent water washes on 'True Grain' type acetates to reproduce layers of gray, fine gestures, or delicate reticulations that are on a par with the most subtle work known from stone lithography. Nik Semenoff was involved in some of the early research into grainy wash media for transparency; see http://www.nontoxicprint.com/lithotonerwash.htm

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Screenprinting the complete water-based system

Carol Robertson / Robert Adam, Thames and Hudson


With clear step-by-step instructions and over 250 illustrations—most in full color—this is a definitive guide to fine-art water-based screenprinting.

Screenprinting has never been so popular—and the water-based process is the best way to do it. This practical and inspirational resource book explains and describes methods and materials that replace traditional toxic screenprinting systems. It is the modern option: safer, healthier, and more environmentally friendly, as well as quick to learn and accessible to all.

Whether you wish to print using photo stencils, paper stencils, or screen filler stencils, with opaque, translucent, metallic, pearlescent, or iridescent paints, on delicate Japanese paper, handmade bark paper, fabric, metal, or PVC, renowned practitioners and art educators Robert Adam and Carol Robertson show you how to do it.

The book covers every stage of the printing process and opens up new areas of creative possibilities, whether printing small editions or works for large-scale installations. From choosing which materials to use and how to use them, through setting up and equipping your own water-based screenprinting studio, to collating and presenting your finished prints, this comprehensive reference book—complete with glossary and list of international suppliers—is the only resource you'll ever need. 265 illustrations, 228 in color. Robert Adam and Carol Robertson worked for nine years at the renowned Edinburgh Printmakers Workshop. They now operate their own studio, Graal Press, and teach printmaking at the Wimbledon School of Art. Together with Friedhard Kiekeben they helped pioneer the European variant of acrylic resist etching in the early 1990s.




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Water-Based Screenprinting
Converting to water-based technology
Roni Henning


  Screenprinting Solutions


I have been a printmaker (primarily screenprinting)

for over thirty years,

making fine art editions for artists,

both emerging and well known.

Among those artists were Agnes Martin, Romare Bearden,

Jack Youngerman, Alice Neel, Andy Warhol,

Red Grooms
and Larry Zox. 

Eighteen of those years were spent at The New York Institute Of
Technology's Screenprint Workshop as their masterprinter-in-residence.
The Workshop was a unique facility that allowed artists to make limited editions of their art in collaboration with the masterprinter. It also permitted the students to have an opportunity to watch prints being made professionally by established and prominent artists. In that way it functioned as a teaching facility. I also taught the screenprinting, etching and design classes at the college. At that time the Screenprint Workshop was a solvent-based facility with oil-based inks and naphtha and acetone as the cleaning materials. Although there were fans there was no exhaust system to remove the bad air and replace it with fresh. Such a system was very costly and the college couldn't afford it. It was after completing a forty color edition of 600 prints that I started to question what I was doing to myself, the environment and my students.

Printers are a rigid breed and once they have developed a system of printing that works well, they are reluctant to change. I myself had felt this reluctance. I didn't realize that if something is poisoning you and the environment it can hardly be considered to be working well, even though the product looks good. Once, when I was working for another print studio in New York City, and I was traveling home on the subway, I overheard two people commenting on how they thought they were painting the subway cars. But I knew it was only me, my clothes smelled of silkscreen ink.

There were water-based inks out there at this time that were used for crafts in the schools but they had a limited, poor color range and because of the water content they also buckled the paper. Some art colleges were using a toner and transparent base system but none of that was professional enough for the artists and galleries that I worked with. I was a printer that was used to mixing colors from gallons of opaque ink with a large diverse palette. I could then add transparent base if need be, but I would also have the opacity if that were what the print required. So I started to look around for options. 

TW Graphics is a silkscreen supplier located in California. They were recommended to me by a fellow printmaker. They offered a line of opaque water-based inks that they claimed was comparable to their oil-based line. So between 1985-86 I tested and printed with their 1000 series. It's one thing to print your own art work and maybe accept some imperfection but not when you are editioning for other artists and major publishers like Pace Gallery. So it took time to get the results that I needed. There were problems; particularly with ink not drying thoroughly and having prints stick together when they were stacked. When working with water-based inks you have to change your methods. Everything has to be blocked out from the inside of the screen not the back. The emulsion must be resistant to water but able to be reclaimed. 

When you pull the squeegee across the screen it isn't as fluid as oil-based ink. All of those issues had to be dealt with. Today those inks have been reformulated and the sticking problems solved. Even the slippery quality of the ink is better. There are other manufacturers like Speedball who have greatly improved their water-based acrylic inks. There are also a few other companies like Standard inks in New York that will give you a good professional result. Createx inks work with a base and toner system and the color range is very good. Even though there is nothing comparable to oil-based fast dry enamel and lacquer inks there is enough variety in the water-based line to make any health and environmentally concerned person switch. Every artist that I work with tells me how wonderful it is to work in a toxic free print shop.

The reason I wrote my first book, Screenprinting Water-Based Techniques, was to showcase the creative, high quality prints that were made with water-based inks and to assist serious printers and artists in their transition from an oil-based system.

When I was experimenting with perfecting my printing techniques with the water-based inks I started playing with other watersoluble materials to see if I could print them through the screen. That's how I started making monotypes with a screen. First I tried various watersoluble crayons and pencils but soon discovered how to use watercolor and gouache to create unique monotypes and monoprints. My second book published by Watson-Guptill, Water-Based Screenprinting Today, devotes a chapter to making a monotype, or monoprint with a screen, and showcases a variety of prints made by other artists working with me.  






Making a Screened
Watercolor Monotype

A monotype or monoprint is simply a painting that is made using a printing process. Traditionally they are made using an etching or litho press. The distinction between the two is determined by how the artist begins. A monotype begins with a blank stretched screen and a monoprint starts with an image or stencil already on the screen. The instructions below are for making a monotype.

Begin the process with a screen stretched with a white 195-230 mesh monofilament fabric. A higher number will give you a finer mesh and image, and a lower number will give you a slightly coarser mesh and image but heavier deposit of color.

Block out the area of the screen that you don't want to print, leaving only the opening that you want the color to pass through. 

The simplest method for blocking out a screen is to draw an opening (square or rectangle etc.) with a pencil and ruler on the inside of the screen. Then apply wide transparent packing tape on the outside of the lines to create the opening. This thin, tacky tape adheres securely and doesn't come off with the pull of the squeegee. 

Cover the rest of the exposed screen to the edges with clear contact (shelf) paper, available at any hardware store. This leaves only the area to be printed open. There are more permanent methods of making an open area on the screen with screen filler or photographic emulsion, but I find that the taped screen is fast and efficient. It's especially useful for the artist that likes to change the size of the opening without having to clean off a permanent stencil.

Once the screen is prepared you can begin the painting process. Each artist approaches a monotype differently. You can paint or draw directly onto the screen just as you would onto paper or canvas, or you can rely on a matrix. This gives you something to work from like a photo or drawing.


Painting The Screen
Screens can be painted anywhere, not just on a printing table. I used to take a screen outside in my garden to paint it.  All you need is a table or flat board on which to prop the screen. Raise it slightly off the surface so the paint doesn't go through. Then begin. 

Any brand of watercolor or gouache will work. Some just work better than others, usually the cheaper brands that have less pigment. Watercolor will release from the screen more easily than gouache which is denser and tends to resist in the screen. This quality gives the monotype an unpredictable result. Experiment with various paints and techniques to develop a more informed idea of how to get the desired results.

If you paint too thickly or one color on top of another, it could cause the colors to resist so only the edges of the painted areas print. You may like these effects, otherwise print in multiple steps if you want to layer colors. The pigment concentrations in different brands also produce varying results. Dry the paint with a hair dryer before printing to prevent it from smearing.





Printing The Screen
All you need to print the monotype is a table, or a board with hinge clamps to attach the screen. Hinge clamps can be purchased at most art or silkscreen supply stores. There is no need for expensive printing equipment. You print monotypes and monoprints with transparent water-based screenprinting base. TW Graphics, Standard, Speedball and Createx are some of the suppliers. You can also get Speedball at Dick Blick. 

Although you can print on any paper or surface I like 100% cotton rag paper, such as Arches cover, Arches 88, Rives BFK, Somerset, or Stonehenge. The smoother, harder paper like Stonehenge is a good choice when printing detail or pencil and charcoal drawings. 

Fasten the prepared screen into the hinge clamps. Hold the front of the screen up with a small block of wood. Mix 10 - 15% retarder into the transparent base to retard the drying time and help the watercolor release from the screen. Two good retarders are Golden Acrylic and Propylene Glycol. Align the paper under the screen and mark its position with registration guides like small pieces of cardboard or masking tape. Place two on the front of the paper in front of the screen and one on the right side.  Tape the paper down if you are not using a vacuum table. This will allow you to print more than once without the paper moving.  You use a squeegee to flood the screen, that means pushing the base across the image while the screen is up. That re-wets the painted area. Flood the screen back and forth 2 or 3 times until you see the color start to dissolve and show on the squeegee's blade. 

Remove the block of wood and lower the screen directly onto the paper. Keep the squeegee at a 45-degree angle and pull it across the image.  Always end your flood stroke away from you so you can print by pulling the squeegee toward you with even pressure. Lift the screen and examine the print. If it is too light and not enough printed you can either flood and print again or you can print on a second sheet of paper.  That would give you two prints that you could print on again when you repaint the screen. Sometimes you can get 4 or 5 lighter versions
(called ghost images) like that, to print over in a variation of the original colors and create a series. Whenever you pull the squeegee across the image make sure that you don't reflood with base that is full of color. That will cause streaks on the next printing. Scrape that base off and pour fresh base in the screen. You can use the tinted base to add to silkscreen ink to make it transparent. Don't discard it.

The printing process adds its own dimension to the character of an image, different from a direct drawing or painting. That is why artists love monotypes and monoprints. There is always the element of surprise after you print and look at the image. Experiment with drawing and painting techniques. Try painting thickly and thinly or wetting the screen and then painting. Once you get used to painting on the screen add watersoluble crayons. Next try graphite pencil and charcoal. Even though they are not watersoluble the pressure of the squeegee forces them through the screen onto the paper.

Once you are finished printing, scrape all the base out of the screen and remove the tape and contact paper. If you have a sink that is big enough for your screen you can wash it there with a good hose. Otherwise you can wash the screen on the table with a sponge, paper towels, and a container of water.  It's so much more pleasant than the old days with solvents. I used to dread cleaning the screen with naphtha. If the watercolor and gouache is hard to remove with water just use simple green or any detergent and a scrub brush to remove the stubborn spots. RH

  


HENNING SCREENPRINT WORKSHOP

Roni Henning is available for contract printing specializing in Monotypes and Monoprints and consultations for converting to non-toxic screenprinting.

Water-based Screenprinting weekend workshops are held monthly at her studio and one-day tutorials upon request.  Check the website for dates and times.

In addition to teaching at her studio Henning teaches on an on going basis at The Lower East Side Print shop in NYC. 






Roni Henning's latest book 
Water-Based Screenprinting Today

published by Watson-Guptill
is also available at amazon.com


Editorial: Master printer Roni Henning has embraced water-based screenprinting for its benefits to both the environment and her personal health. In this insightful guide, she has gathered the works, techniques, and experiences of many of the talented artists and printers with whom she has crossed paths during her own illustrious career, printing editions with the likes of Romare Bearden, Andy Warhol, and Jack Youngerman.

Through the work of Bearden, Youngerman, and Gene Davis, among other top artists, you are guided through the traditional screenprinting process, from building and stretching a screen to color separations, color mixing, proofing, and printing. Henning discusses advances in techniques and process since the rise of water-based screenprinting, the collaborative relationship between artist and printer, and monoprints and monotypes as art forms. Finally, the use of computers and image manipulation software to complement screenprinting is also investigated.


Contact Roni Henning:
Email        roniprint@aol.com
Website    www.ronihenning.com
Phone       917-841-5704

watch an introductory video on Roni's nontoxic printing process on her home page:
http://ronihenning.com/home/


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Screenprinting Websites



  Squeegeeville

Squeegeeville is a website dedicated to the art and technology of screenprinting. Since its creation in 2000 the site has gone through a number of changes as their focus has evolved. This is the newest incarnation and concentrates on 6 key areas:
  1. Free instruction and information for novice and advance screenprinters: including links and PDFs of articles published in a range of trade magazines around the world.
  2. Training and workshops at their facilities or yours: including intro courses and more advanced training to get you printing right the first time.
  3. Products and Services: including the book Screenprinting Today - The Basics, prototyping and product development, custom screenprinting, and fine art printmaking.
  4. An on-line art gallery: featuring limited edition serigraphs by Canadian and international artists, gigposters, and other interesting prints.
  5. Links and resources: to help you find other websites that contain good information about screenprinting, artists, associations and more.
  6. The News Section: giving visitors an opportunity to ask questions, find answers, and read about the latest goings-on in Squeegeeland.



Hester Stinnett's Waterbased Screenprinting Handbook



Hester Stinnett’s work has been exhibited nationally and internationally, and is in numerous private and public collections, including the permanent collections of the National Gallery of Art, Philadelphia Museum of Art, and the Walker Art Center. In 2004 she was awarded a Pennsylvania Council Artist Fellowship for Works on Paper. She was an Artist in Residence at the Fabric Workshop in 2003, and has presented printmaking workshops at the Haystack Mountain School of Crafts in Maine and the Anderson Ranch Arts Center in Colorado.

With co-author Lois M. Johnson she wrote Water-based Inks: A Screenprinting Manual for Studio and Classroom published by the University of the Arts Press with grants from the NEA and Hunt Manufacturing Co.


Currently Professor of Printmaking at the Tyler School of Art of Temple University, she has also taught at The Pennsylvania Academy of the Fine Arts, The Philadelphia College of Art (now University of the Arts) and Bryn Mawr College. She received a BFA from the Hartford Art School, University of Hartford and an MFA from the Tyler School of Art of Temple University.

                                                                                            Send emails to:
hesters@temple.edu

                                                                                                                                                                          
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SCREWBALL ACADEMY

Since 1991, Steve Walters (under the moniker Screwball Press) has been printing posters, CD packaging, and a variety of other collectible items for Chicago's indie rock community. Over the years, he has had the opportunity to train and/or work with some of his favorite local artists including Bob Hartzell, Kristen Thiele, Jay Ryan, Mike Benedetto, Keith Herzik, and Jason Frederick. Around 2000, Steve looked back on ten years of work and realized that working with these people was the single most satisfying aspect of Screwball Press. So he began to implement the Screwball Academy based on the extension of the Minutemen's "band in every garage" credo. Steve wanted to see a printer in every band. 

At present, Steve has taught 36 people over the past 18 months, most of whom still use the facilities to print personal projects as well as a few who run their own printing businesses.

THE DEAL

Screenprinting is a physical, hands-on process and so is the course. Students come in with a piece (or 2) of black and white line art and leave with up to 50 3-color, 11"x17" prints that they produced themselves. This can be done in a single 6-8 hour session or can be broken up into two shorter sessions. After that, you are free to come back whenever you want to use the facilities.

To schedule a class, email Steve at steve@screwballpress.com





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SILK SCREEN PRINTING 
By Ronald Fuchs and Michael McCann, Ph.D., C.I.H.
http://www.uic.edu/sph/glakes/harts1/HARTS_library/silkscrn.txt


 
UIC Health in The Arts Library


 Silk screen printing is one of the most hazardous processes in

the arts and crafts. Dermatitis, narcosis (dizziness, light-

headedness, fatigue, nausea, lack of coordination and headaches),

eye irritation, adverse reproductive hazards including increased

risk of miscarriage, and serious neurological problems can all

result from the processes of screen printing.



Traditionally, silk screen printing has been performed using organic solvent-

based materials. Water-based inks containing less hazardous

ingredients provide a safer and increasingly popular alternative.



SOLVENT-BASED SILK SCREEN PRINTING Hazards The major hazard in silk screen printing comes from exposure to the solvents in the inks, thinners, clean-up materials, etc. Thinners such as lacquer thinner and are a mixture of these and other hazardous solvents. The greatest

hazard is exposure through inhalation, causing narcosis

(dizziness, headache, nausea and light-headedness) from acute

exposures, and skin, liver, kidney, reproductive and nervous

system damage with repeated exposure.
Skin absorption can also

produce these effects. It is also important to note that most of

these solvents are flammable.
An industrial hygiene study of a university silk screen printing class verified that silk screen printing without adequate ventilation can be extremely hazardous. This study measured the breathing zone exposure of students and teaching assistants during printing using poster inks, and cleaning using toluene, xylene, mineral spirits, and lacquer thinners.


 Without ventilation, measured air concentrations during

printing were 100 parts per million (ppm) of toluene for 100

minutes, 600 ppm of toluene and 92 ppm of xylene for 421 minutes,

and 410 ppm of toluene for 60 minutes. During cleaning, the

following measurements were made: 670 ppm of toluene for 28

minutes; 490 ppm of toluene and 250 ppm of methyl ethyl ketone

for 8 minutes; and 1900 ppm of toluene, 95 ppm of xylene and 180

ppm of methyl ethyl ketone for 34 minutes.
With local exhasut ventilation, the exposure levels were many times lower with most measured concentrations below 1 ppm, and all below 50 ppm. By way of comparison, the American Conference of Governmental Industrial Hygienists (ACGIH) has set Threshold Limit Values (TLVs) of 100 ppm averaged over an 8-hour day for toluene and xylene, and 200 ppm for methyl ethyl ketone. The ACGIH 15-minute TLVs are 150 ppm for toluene and xylene, and 300 ppm for methyl ethyl ketone. As you can see, the air sampling carried out greatly exceeds these ACGIH recommended exposure levels.

Screen Preparation
The hazards associated with screen preparation depend on the materials used. For resist and blockout stencils we recommend water-soluble glues, liquid wax and liquid frisket which contain no toxic solvents nor require them for clean-up. They may cause slight eye irritation if they splash in the eyes. Lacquers, polyurethane varnishes, tusche, shellac and caustic resist enamels are often used but contain large amounts of toxic solvents. Turpentine, used to thin tusche, may cause skin or respiratory allergies, and kidney damage.


 For film stencils, water-soluble emulsion films are

recommended. The mixture of water and isopropyl alcohol adheres

the stencil to the screen, and while flammable, is only slightly

toxic. The adhering fluid for lacquer-type emulsions contains

acetates, ketones and alcohols, which are irritating to the skin

and are more toxic by inhalation.
The safest type of photostencils are diazo photoemulsions. They are eye irritants by direct contact, but are otherwise not very toxic. Ammonium dichromate, often used to sensitize photoemulsions, can cause skin ulcers and allergies with direct contact and inhalation of the powder can cause severe respirat- ory irritation, ulceration of the nasal septum, and respiratory allergies. Ammonium dichromate is also combustible. Silver nitrate, another sensitizer, is corrosive to the skin and eyes. Carbon arcs, sometimes used to expose photoemulsions, are highly hazardous, giving off metal fumes, ozone and nitrogen dioxide, which are strong lung irritants, and ultraviolet radiation which harms the eye; carbon arcs are not recommended.

Printing and Drying
Many silk screen inks contain up to 50 percent hazardous organic solvents. Poster inks can contain toluene and xylene, which are highly toxic aromatic hydrocarbons, and large amounts of mineral spirits. Other inks, e.g. vinyl inks, can contain large amounts of other highly toxic solvents, for example, isophorone. The bases, thinners, retarders, etc. used with these inks also contain similarly hazardous solvents. Direct exposure to the solvent vapors from the ink is a serious problem during printing due to the close proximity of the printer. Inhalation of the hazardous solvents during drying, however, is the major source of exposure since large volumes of solvent evaporate into the air in a short period of time. Curing fabric inks by heating may release fumes which are irritating to the respiratory system. Clean-up Clean-up is probably the most hazardous step in silk screen printing because of the widespread use of highly toxic screen washes and the practice of tossing solvent-soaked rags in open wastepaper cans. This causes the evaporation of large amounts of highly toxic vapors.



To reduce exposure to toxic vapors during

clean-up, substitute mineral spirits (or mineral spirits with 15%

added xylene for difficult jobs) for lacquer thinner, toluene,

xylene and other highly toxic solvents. These solvents are also

fire hazards.





Precautions Proper safety is essential when working with all these toxic substances. The elderly, people with chronic diseases, pregnant women, and children are at especially high risk and should avoid screen printing if possible. Consult your physician if you suffer from heart trouble or a breathing ailment which can be aggravated by toxic vapors. The following precautions will help reduce the dangers in the processes of screen printing. Fire Precautions Solvents should be stored in approved, capped flammable storage cabinets. Only a small amount of solvents should be out for use and solvents should be purchased in the smallest quantities practical in order to minimize fire hazards. Before starting work, all sources of ignition should be eliminated. See the CSA checklist on storage and use of flammable and combustible liquids. Ventilation One of the most important precautions in silk screen printing is proper ventilation. Research conducted by the Harvard University School of Public Health in a university silk screen printing classroom, showed that printing without adequate ventilation causes exposure to very hazardous levels of the solvents used. All processes producing solvent vapors -- including printing, drying and screen washing -- should be done with local exhaust ventilation.


 During the printing process, the best type of ventilation

would be an explosion-proof slot exhaust hood located at the rear

of each printing station. The drying rack should be enclosed on

the back, sides, and top, and the solvent vapors exhausted from

the rear. For example, an explosion-proof window exhaust fan can

ventilate the drying racks, if the enclosed rack is placed right

in front of the window.
Clean-up can be done at the printing table utilizing the local exhaust slot hood. Bleach cleaning of the photoemulsion screens also needs local exhaust ventilation because of the chlorine gas produced.
Air conditioners do not adequately ventilate screening processes because they recirculate air rather than exhausting it. (Even when air conditioners are set on "exhaust" they recirculate about 95 per cent of the air). Likewise, open windows or doors are not adequate ventilation for solvent-based silk screen printing.

Respirators
A National Institute of Occupational Safety and Health (NIOSH)-approved respirator with organic vapor cartridges can help minimize exposure to screen printing solvent vapors if ventilation is not adequate. Sources for respirators and rules for selection and use of respirators are included in the Center for Safety in the Arts (CSA) data sheet on Respirators (see CSA Publications List).
Eye Protection
To prevent eye irritation caused by splashes, wear lightweight plastic splash goggles while pouring or working with paint removers. Choose goggles which are approved by the American National Standards Institute (stamped with a "Z87"). These can be found in most chemistry supply houses and safety equipment stores and some hardware stores. If ink or other hazardous material is splashed in the eyes, flood the eyes with water for at least 15 minutes and call a physician. A source of clean water (e.g. eyewash fountain) should be accessible for this purpose.
Hand Protection
Gloves should be worn during all screen printing processes to protect the skin from hazardous pigments, solvents and other chemicals. Ordinary rubber dishwashing gloves or surgical gloves will not provide adequate protection. All gloves do not provide protection against the same materials. When using inks, gloves that protect against aromatic solvents and petroleum distillates should be used. Lacquer use requires wearing gloves that protect against ketones and alcohols besides aromatics and petroleum distillates.


You should find out the type of solvents in the

products you use by consulting the specific MSDSs. (For further

information on gloves, consult the CSA "Glove Selection" data

sheet). To further decrease the risk of skin contact wear long

pants, a long sleeved shirt and an apron.



Disposal Solvent-soaked rags should be stored in approved oily waste cans which are emptied daily. Disposal should be done in accordance with local city and fire regulations, and an approved waste-disposal firm may be necessary for large quantities of solvent waste. Never pour solvents down the drain. Small quantities of solvents can be evaporated under a fume hood or outdoors.
WATER-BASED SCREEN PRINTING
Because of the extremely high cost of providing adequate local exhaust ventilation systems in classroom situations, there has been a switch to water-based screen printing products. In recent years the quality of these inks has improved remarkably, and many professional artists as well as printing studios have switched to water-based products. Flat, opaque, hard-edged traditional looking prints are still possible, and dye-like transparencies and washes rivaling watercolor and lithography can also be produced. The same wide variety of stencils can be used with this medium as with the solvent-based inks.
The changing over to water-based inks means the incorporation of a whole new system and requires understanding of this new medium. It is necessary to take time and learn how to produce successful images.


After learning how to work with water-based

products, artists and instructors report that the colors are

beautiful, the inks don't dry on the screen, and paper designed

specifically for water-based screen stays flat. In addition the

overall cost of printing with water-based silk screen inks is

cheaper than with solvent-based inks because water is used for

cleanup rather than the more expensive solvents.



Hazards The inks and cleaning materials employed in water-based screen printing use water instead of toxic organic solvents. Airborne organic vapors, skin absorption of organic solvents and the risk of fire are greatly reduced. Small amounts of organic solvents may be used in water-based screen printing inks.



We recommend products with only water, propylene glycol or ethylene glycol.

Glycol ethers such as cellosolve are much more hazardous since

they can cause anemia, kidney damage, and adverse reproductive

effects such as miscarriages, birth defects, testicular atrophy

and sterility. It is necessary to get material safety data

sheets (MSDSs) on all products in order to ascertain the ink

composition, since the ingredients are not always listed on the

label.
Use of diazo photoemulsions can completely eliminate the need for solvents. If lacquer stencils are used, then the hazards discussed earlier for solvents will apply, although to a lesser extent since smaller amounts of solvents are used.
Precautions Basic personal hygiene is a must for all those working with art materials. Water-based screen printing is no exception. There should be no eating, drinking, smoking or make-up application in the studio or while working.



Hazardous pigments and some toxic solvents are still used in the manufacture of

water-based inks and related materials. To avoid ingestion and

absorption of these substances through skin contact, wearing

gloves is recommended while working in this medium. For water-

based printing, a window exhaust fan should provide adequate

ventilation and costs much less than a slot exhaust hoods or

other complicated ventilation systems. If lacquer stencils are

used, then one explosion-proof slot exhaust hood would be needed

for this process.



REFERENCES Babin, A. and Rossol, M: "Glove Selection". Center for Safety in the Arts, New York (1988). Clark N, Cutter T, and McGrane J: Ventilation. Nick Lyons Books New York (1984). Johnson LM and Stinnett H: Water-based Inks: A Screenprinting Manual for Studio and Classroom. Philadelphia Colleges of the Arts Printmaking Workshop (1987). McCann M: Artist Beware: The Hazards and Precautions in Working with Art and Craft Materials. Watson-Guptill, New York (1979). McCann M: "Silk Screen Printing Hazards." Art Hazards News 2:7 (1979). McCann, M: "Respirators". Center for Safety in the Arts, 1988. SOURCES OF ADDITIONAL HELP Written and telephoned inquiries about health hazards in the arts will be answered by the Art Hazards Information Center of the Center for Safety in the Arts (formerly the Center for Occupational Hazards). Permission to reprint this data sheet may be requested in writing from the Center. For a copy of our publications list, send a self-addressed, stamped envelope to: Center for Safety in the Arts, 5 Beekman Street, New York, NY 10038. Telephone 212/227-6220. This data sheet was revised with the assistance of a grant from Special Projects, Visual Arts Program of the National Endowment for the Arts. The Center for Safety in the Arts is partially supported with public funds from the National Endowment for the Arts, the New York State Council on the Arts, and the New York City Department of Cultural Affairs. (c) Copyright Center for Safety in the Arts 1988





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