Addressing the ‘safe’, ‘eco-friendly’ and ‘water wash’ statements in flexographic polymer plate-type printmaking and finding safe working methods
a photopolymer print by Henrik Boegh (Cambodia);
Photopolymer plate printmaking is highly regarded as a form of photo-reprographic art in intaglio and letterpress printmaking
During processing Photopolymer Printing Plates may emit: Vinyl chloride gas / styrene gas / benzene / hydrofluoric acid vapor / …
This article is based on an arduous and extensive research process into flexography safety that started in 2010 / key aspects from various sources that were prompting this ongoing work are confidential; some sensitive information is held in our archives and cannot be disclosed.
Fact: In private advising conversations reputable public health officials strongly warn about the (hidden) dangers of this process.
Fact: Major manufacturers of plate products do not make reference to fume emissions from ‘water wash’ flexo methods commonly used in art. But experts think emissions do exist.
Fact: Today it can be assumed / suspected that the majority of flexographic plate products are patented vinyl chloride-styrene-butanienne-polymer type admixtures, and often it is near impossible to determine exactly what the plate chemistry is.
Fact: Users may not be able to tell there are concerns, due to lack of strong smells or visible reactions. Product literature makes no reference to hazards.
Fact: Even industrial plate processors are often lacking the extensive fume extraction that may be needed to deal with possible emissions especially during plate ‘scrubbing’ in open air under running water.
Fact: Flexo plates are no longer thought to be ‘true’ acrylics, (as was sometimes claimed) and the polymer mixture typically contains only a minimal amount of acrylates (which have the relative safety levels of acrylic paint).
DANGER: By some, this method is suspected to possibly involve undeclared and poorly detectable harmful and carcinogenic emissions! Artists are advised to not use this process without full and adequate protective measures, especially during final plate scrubbing, perhaps working in a chemistry-department type fume hood. There is debate how to protect users; and we are waiting for more fully resolved guidelines from safety experts and the industry itself.
For about twenty years there have been recurring anecdotal suggestions from regular users of photopolymer printing plates (Flexo / S… plate / Letterpress Photo-polymer Plates with a hard metal or polyester base) who believe they may have got sick or seriously sick from this common plate making process that is popular and widespread in artist’s intaglio and letterpress printmaking, and in the printed packaging flexographic industry (for printing on cardboard boxes). It would be for government medical data bases and expert medical and public health officials to know and verify details of such claims; little is currently known in the public domain.
The recent history of this issue: Photo-sensitive flexographic rubber printing plates –often solvent based–have been used since mid-century, and their significant toxicity was known early, as is documented in medical records and law suits. More recently (over the past 30-35 years) new types of ‘water wash’ flexographic plates were introduced, that are (is claimed) solvent free. These were and are formally advertised as ‘safe / water wash’ products by large chemical corporations and many artists and even experts believed the chemistry was acrylic and acrylates based (MMA chemistry), with safety similar to acrylic paint.
With many of these products there was no way to determine the exact chemical composition or potential toxicity due to patents and possible omission of potential issues on product packaging and in safety data sheets. However, it had long been known that cheap non-branded products often contained large amounts of carcinogenic toxins; which caused some experts and this resource to raise a degree of concern (is water wash truly safer than solvent based flexography?) from early on.
In the early 2000s Keith Howard rejected the use of flexographic methods after study of available literature, and in consultation with DuPont photopolymer chemists, and chose the modern pathways of PCB dry films instead; these dry films have proven acrylate chemistry (MMA), and a relatively well documented safety record in circuit board manufacturing. The dry film chemistry has built in break-down of monomeric toxins through sodium carbonate saponification in plate development, flexography does not.
Despite the anecdotal hazard and sickness reports — and extensive advice from public safety experts — there was little published information about possible exposure mechanisms that could be a likely cause, and the process seems at first glance ‘waterbased’, ‘water-washable’, and of low hazard. But there were early warning signs: Significantly, the flexographic printing industry has long had significant and sustained numbers of law suites related to cancer in workers working in flexographic plate making; with vinyl chloride and asbestos poisoning as a likely cause; and some law firms appear to specialize in that area.
NOTE: the dry photopolymer films from the circuit board and IT industry differ greatly from photopolymer plates; the polymer chemistry of dry film is more modern (it is not PVC based, but acrylates based) and has better proven safety credentials than flexographic plates
Product literature for photopolymer printing plates makes little reference to such hazards, and instead suggests user friendliness because of the ‘water wash’ processing method. In polymer plates artists are using an industrial product that is designed for fully enclosed machine processing (known as closed circuit polymerization) with appropriate extraction systems in the packaging and printing industries.
Professional industrial facilities that process these PVC / Nylon type polymers in the rubber, tire and printing industries have long avoided open tray ‘hand processing’ that involves VOC emissions, and replaced it with fully automated machine processing which is essential for safety. Polymerization chemistry is kept away from the workers.
We strongly advise artists against the regular use of hand processing of any type of photopolymer (flexo-type) plates, unless a full organic / inorganic combined respirator and ventilation are consistently employed during all steps of this particularly insidious process, which may seem quite safe when it probably isn’t safe if used without full protection!
a photopolymer plate processing machine. the ‘treatment’ section needs to be connected to a fume extraction system that vents to the outside.
Print shops and institutions are advised to purchase professional, fully enclosed, and automated plate processing machines with full extraction systems in order to ensure a safe plate making processes.
In studio tests we found evidence that water wash photopolymer plates may emit significant amounts of poorly detectable VOCs or SVOCs, (semi volatile compounds such as vinyl chloride), as well as possible acid / alkaline vapors (possibly hydrofluoric acid — this was named in plate literature) all at once, mainly during the final ‘scrubbing’ phase once the plate is in contact with air, following the tray development in water. These fumes are hard to detect but may have a sweet smell which indicates the presence of airborne vinyl chloride, butadiene, benzene, or styrene monomer, all of which are known and powerful carcinogens.
Some of these speculative facts acts about possible flexographic plate chemistry and processing reactions, and toxicity, have only slowly emerged — through intense investigation — over the past twenty years; neither industry nor public health officials publish reliable data.
Speculatively, this may be an exposure mechanism at play: Heavy and semi volatile fumes can concentrate and react with air and water above the plate surface during scrubbing and rinsing, exposing artists to significant amounts of toxins without ever noticing it. Unknowingly, regular users of this popular photo-intaglio plate making process may expose themselves to invisible and cumulative hazardous emissions that may increase the likelihood of ill health or cancers after a few years of working with this method / quick bursts of solvent / acid / alkaline emissions during scrubbing may exacerbate the impact of solvent exposure, and create pathways into the body.
Although flexo plate manufacturers do not typically disclose the patented composition of their resins or their plates, — and do not list processing emissions in ssd sheets — it is widely known that some key monomeric components of flexographic plates (from various manufacturers) may be polyvinyl chloride (PVC), and sometimes Nylon, in combination with a small amount of acrylates (for instance MMA or Ethyl Acrylate).
Styrene-butadiene-styrene (SBS) block copolymers are commonly used as a primary binder or a component in the resin formulations for some types of photopolymer flexo printing plates. (Photopolymer.com).
SBS is a thermoplastic elastomer that provides the necessary flexibility, elasticity, and mechanical properties required for a flexographic printing plate. The complete photopolymerizable composition typically also includes ethylenically unsaturated monomers, a plasticizer, and a photoinitiator.
Other types of resin chemistry can include:
• Styrene-isoprene-styrene (SIS) block copolymers• Copolymers of butadiene and acrylonitrile• Acrylated polyurethanes & nbsp
NOTE: 1,3-Butadiene: Known carcinogen (EPA) and probable human carcinogen (IARC Group 2A). Exposure linked to leukemia, reproductive/developmental issues in animals, and respiratory irritation.
essentially, flexographic plates and processes typically entail similar toxic hazards and occupational sickness profiles as are common in the car tire industries and synthetic rubber manufacturing
Rubber Printing Plates may be composed of up to 50% PVC
The PVC content in these plates may be at a percentage of up to 50% to provide flexibility as well durability of the UV sensitive printing plate (quoted from: Sun Chemical). Vinyl Chloride monomer is powerful carcinogen, and is linked to various kinds of cancer, including brain cancer.
National Library of Medicine (excerpt):
https://www.ncbi.nlm.nih.gov/books/NBK533528
“Vinyl chloride has been associated with tumours of the liver, brain, lung and haematolymphopoietic system1. A large number of epidemiological studies2–12 and case reports13–25 have substantiated the causal association between vinyl chloride and angiosarcoma of the liver. Several studies also confirm that exposure to vinyl chloride causes other forms of cancer, i.e., hepatocellular carcinoma13,19,23,26, brain tumours11,27, lung tumours12,28–30 and malignancies of the lymphatic and haematopoietic system11,29,31“
Treatment of Washing Water: Photopolymer Plate Making produces large amounts of monomeric plastics, heavy metals, and solvents that enter the washing out water during processing. Do not discard this effluent down the drain, but use a flocculation method to break down this sludge into safe components that can be filtered and discarded. See page:
some sources:
Sun Chemical
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The Editor, 2026