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Photopolymer

How many impressions can I get off a plastic-backed photopolymer plate?

If you take care of them, the plates will last for as many impressions as you need them (or for years of use). Plastic-backed photopolymer, in commercial applications, lasts for thousands of impressions – the plastic is incredibly hard and durable. Read about how to take care of your polymer plates.

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What’s the smallest size plate that I can print on my Boxcar Base?

The Boxcar Base is guaranteed to hold plates in register, provided they are standard thickness plastic-backed plates mounted with our film adhesive. But plates that are smaller than .25 square inches may drift under certain conditions due to their small area of contact with the base. Make sure your plates are larger than .5″ by .5″, even if your image is very small.

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How are plastic-backed and steel-backed plates different?

When mounted on their appropriate bases, plastic-backed and steel-backed photopolymer plates both create type-high surfaces for letterpress printing. Both plate types are recyclable. We’ll talk about some of their differences below.

Plastic-backed polymer plates are flexible, transparent, easy to cut, and mount onto a Boxcar Base for simple registration. You’ll find these plates:

  • can be cut with scissors in both their unexposed and exposed forms.
  • are transparent, meaning you can see the Boxcar Base’s grid through your plate. This allows for simple alignment of your plates to your base: For perfect registration, align a certain element of your plate to the grid: take a horizontal or vertical element in your plate (this could be your registration marks, or a horizontal line in your artwork) and line it up to the grid.
  • eliminate plate creep (steel-backed plate users sometimes experience this while on press). The plastic-backed plate’s adhesive is shift resistant, giving you a secure, strong hold during printing (but the adhesive also peels up easily when you’re done printing)
  • allow printers to print two color jobs using one plate if the design elements don’t touch. Cut out the second color images/text with a craft knife or scissors and set aside. Print color #1. Set your second color images back in place and pull up the first plate for color #1—perfect registration!
  • allow designs to be ganged up on plates closely to save space (and money).
  • are reusable. You will be able to reuse the plate many times if you keep the adhesive protected with the blue overlay after printing.  You can also replace adhesive for even more extended plate use.
  • more prone to curling, especially with large solid areas over time.
  • If purchasing unexposed plastic-backed polymer plates, you’ll also want to purchase film adhesive to adhere your plates to your base. If we’re making your plates for you, we include adhesive.
  • are suitable for metal clay jewelry.
  • Over here at Boxcar, we use plastic-backed plates for all our printing (the Jet 94 Clear plate paired with the Standard Boxcar Base).

Steel-backed polymer plates are compatible with magnetic bases, generally the Patmag or Bunting base. Steel-backed polymer plates:

  • require cutting with a metal shear or heavy-duty trimmer. You can use tin snips, though you may end up with kinks in your plate, as tin snips won’t cut as cleanly.
  • sometimes shift and creep on your base during printing. Magnets in the base effectively hold a plate from peeling but cannot always hold a plate from moving side to side. The cylinder or rollers of a press can move steel-backed plates out of register (that’s “plate creep”).
  • are not transparent. Because magnetic bases aren’t gridded (and you can’t see through these plates),  you’ll have to align your plates to your base with a line gauge and possibly registration marks. This works, but it is more time consuming and there’s more room for error.
  • are rigid, meaning they don’t bend well. This inflexibility can cause plates to kink and warp when handled so that their corners may work up while on press. Steel-backed plates are, however, very durable and not prone to curling over time.
  • can be more expensive than plastic-backed plates because you may require registration or crop marks which makes for a larger plate.
  • are difficult to get on and off the base, especially when the base has inlaid magnets. When placing metal plates on a magnetic base, keep fingers clear so they don’t get pinched when the magnet grabs. When taking your plate off the base, try an ink knife to pry under the plates to release from the magnetic base.
  • have sharp edges, which dictate extra care when handling.
  • can be used for a wide range of printing and impression—on leather, metal clay jewelry, ultra heavy-weight paper stocks. Steel-backed plates can also be used on etching presses when relief printing is desired. They are not suitable for high temperatures of foil stamping though.

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I have a Boxcar Base. What plates do I purchase?

Standard Boxcar Base users:  We offer 3 different plate types for the Standard base.  A popular plate type is the Jet 94FL.  If you are using the plates for a long period of time, this plate resists curling and brittleness the longest.  Another option is the KF95 plate. However, some printers find they prefer printing with our hardest plate – the Jet 94 Clear (94CHFB). The harder plate has the least compression when printing, and gives less distortion than the 94FL on type smaller than 8 points. However, the 94 clear plates do get brittle in as little as 3 months so they are best for short term or limited use jobs.  All 94/95 plates are the same price per sq inch for our platemaking service.

Deep Relief Boxcar Base users: The KF 152 plates work with our Deep Relief Boxcar Base.

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I have a Patmag base. What plates do I purchase?

For the Patmag base user: we recommend the 152SB plate for most letterpress printers. Some printers find they prefer printing with a harder plate, the 145HSB. This harder plate gives less distortion than the 152SB on type smaller than 8 points or on thin lines. However, the 152SB holds slightly better detail. The 145HSB plate is a little less flexible than the 152SB and may crack if flexed too much on the magnetic base.

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I have a Bunting base. What plates do I purchase?

For the Bunting base user: the Bunting Base can be any height, but typically, the bases pair up with the 152SB or (less often) the 94SB. Bases that measure .858” use the 152SB. Bases that measure .880” use the 94SB. Use a micrometer or calipers to measure your base. You can also send in a polymer plate that’s worked on your Bunting Base in the past, and we can match it up to the appropriate plate.

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I want to use photopolymer to do something other than letterpress printing. How do I know what plate to use?

While our troubleshooting only extends to using photopolymer plates for letterpress printing, there are literally dozens of other uses for photopolymer plates. If you know the tech specs of the plate that you need, or if you can send us a sample of the plate required for your application, we would be happy to try and recommend a plate that we have in stock that will work for you.

We have innovative people using our plates for metal clay jewelry making, translucent porcelain, and leather work. We always like to hear what you want to try.

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Is processing a photopolymer plate toxic?

None of the byproducts of processing photopolymer plates are known to have health risks, except if you’re allergic by contact to plastic. Check out the MSDS’s for more specific health information. You can find each plate’s MSDS on it’s product page: plastic-backed plates; steel-backed plates; intaglio plates.

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How do I process my photopolymer plates?

Because processing your own plates can get complicated – and the results need to be excellent for quality letterpress printing – we recommend using a dedicated photopolymer platemaker. If you don’t already own one of these machines, we can help you source out light boxes, washout and exposure units, whatever your budget. If you’d rather learn how to hand-process your plates, we recommend checking out Letterpress Commons and, if you can, taking a class at one of these great book arts centers: Center for Book Arts (NYC); Minnesota Center for Book Arts; San Francisco Center for Book Arts; Columbia College Center for Book and Paper Arts (Chicago). You’ll find essential exposure information in your plate’s datasheets, though you’ll want to use a Stouffer Gauge to perfect exposure. We can always process your plates professionally for you through our platemaking services.

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How do I process my intaglio plates?

Boxcar Press provides unexposed plates for intaglio and etching artists who want to create prints using a safer and more environmentally friendly process. Because we specialize in letterpress printing, we do not process intaglio plates at our shop. We can’t offer instruction on how to process these plates. But in an effort to assist artists with their intaglio process, we recommend the following books and web sites, written by people who are creating and experimenting with polymer in terms of correct UV exposure, wash out times, creating transparencies, homemade UV light boxes and more.

Overviews and Glossary

Technique

Instructions and Suppliers – Light Boxes, Brayers, Inks, Aquatints, Negatives

Learn more with videos and books

  • Video on Etching and Screenprinting – Chicago Printmakers Collaborative
  • Intaglio: The Complete Safety-First System for Creative Printmaking: Acrylic-Resist Etching, Collagraphy, Engraving, Drypoint, Mezzotint By Robert Adam, Carol Robertson
  • Etching and Photopolymer Intaglio Techniques, by Colin Gale
  • Printmaking in the Sun, by Dan Welden and Pauline Muir (Amazon)
  • Polymer Photogravure: A New Method for Photographers and Graphic Artists, by Taneli Eskola and Kan Holopainen
  • Intaglio Printmaking (Printmaking Handbooks) By Mychael Barratt

Other links to useful and interesting Sites

We hope this information helps you in the process of what you’re trying to achieve. Please help us to spread the good news by letting us know about other useful sources.

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I’m a metal clay artist. What photopolymer plates do I use?

We carry plates that are very similar to those recommended by Art Jewelry Magazine. Many metal clay artists have used our plates to great success. We have several plate types that will suit your needs and preferences.

What Boxcar photopolymer should you use for metal clay?
Art Jewelry Suggests Boxcar Press plate Boxcar plate thickness Plate material Impression
0.8mm 94FL .94mm/.037” plastic backed shallower
1.52mm KF152 1.50mm/.060 plastic backed deep
0.9mm or greater 94SB .94mm/.037” metal backed shallower
0.9mm or greater 145HSB 1.40mm/.057″ metal backed medium
1.52mm 152SB 1.50mm/.060″ metal backed deep

Boxcar Press offers two options to metal clay artists. We can sell you unexposed polymer plates for do-it-yourself artists to create their own negatives and process themselves. Check out our new Plates by the Pound service for our plastic backed plates under our Supplies. Or we can take your digital files or images and professionally create plates for you, quickly and economically.

In either case, you will want to store your exposed plates in a zipper bag out of sunlight. You may also want to consider using a silicon spray to protect the plate from the moisture in the clay. You will want to clean the plate with vegetable oil.  Exposure to too much light and moisture will cause your plates to deteriorate.

Remember, we’re a letterpress shop, and letterpress is our expertise. We can’t answer specific questions about how our plates work with your process, but we can offer information on the polymer plate material, thickness, exposure times, and processing.

For additional information, you may also want to check out:

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Do I need to order adhesive if I’m having a plastic-backed plate processed by you?

No! Any plate that will be printed on a Boxcar Base will have Boxcar film adhesive applied at no charge.

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What’s the maximum size polymer plate I can print on my base?

Your maximum plate size is actually the size of your base — your photopolymer plates can go right up to the edge of your base. Obviously your relief images and text should not hang over your edge. This is true for both magnetic bases and the Boxcar Base.  If you need a little more base for occasional projects, consider a Boxcar Base scrap to add that extra ½” – 1”.  Read more about maximum base size.

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What do I need to be able to letterpress print with your photopolymer plates?

You’ll need:

  • a printing base. The polymer plates we create aren’t type high by themselves. They need to be mounted on a base to make a type-high printing surface. We recommend our Boxcar Base system. Letterpress printers also use magnetic bases from Patmag or Bunting. If you are printing on a DIY press such as L Letterpress, please refer to this tutorial.
  • a Printing press. Remember that most letterpress printing presses people purchase will not be ready to print beautifully right away and a little tender loving care will be needed. Be prepared to purchase new rollers or do other maintenance on your press!
  • Ink. we recommend Van Son rubber-based letterpress inks, which you can order in any uncoated Pantone number! Or you can purchase the Van Son base colors and mix your own colors. View the inks we carry.
  • various pressroom supplies, including printers furniture, quoins, tympan paper, type gauge, ink knife and (if using a platen press) Kort gauge pins or Henry gage pins.
  • a fashionable printing apron

We now sell letterpress starter packs, which contain a lot of what you’ll need to get started.

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What’s the biggest problem that printers new to photopolymer encounter?

Photopolymer plates offer an way to letterpress print extremely detailed designs with a deep heavy impression (or a kiss impression if you’re so inclined). The chief problem that new photopolymer users encounter usually deals with roller height/roller condition. But no worries! Unlike larger problems like war or global warming, roller issues do have concrete and relatively easy solutions. We recommend rubber rollers and, if using a platen press, solid trucks. If switching from lead type/magnesium plates, you’ll want to keep a much closer eye on your rollers. You may find our general printing FAQ’s useful, especially if you’ll be using a Boxcar Base.

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