It depends on the plate. If you're purchasing unexposed plastic-backed plates, you'll need adhesive to adhere the plate to your printing base. We sell adhesive in 12x18 sheets and 27 yard rolls. Apply to the back of the plate after processing. If you're purchasing unexposed steel-backed plates, there's no need to purchase adhesive. Adhesive is included if we process the plastic-backed plates for you.
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As long as you're careful about not getting dust or debris on the adhesive, and you carefully replace the silicone release paper after use, the adhesive should remain sticky for many years. Keep in mind that adhesive can always be inexpensively replaced.
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When your rollers are positioned correctly, your printing will look beautifully crisp. This is because correctly positioned rollers deposit a thin film of ink onto the surface of your printing plate (without squeezing ink over the plate’s edges). But if your rollers aren't positioned at the right height, your printing will have a halo effect: dark around the edges and/or chunkier/blotchier than it should be. If you ever notice ink on the back of your polymer plate or on your base -- it's a roller gauge emergency! Adjust your rollers now! Here’s how.

Step 1. While your press is inked up, remove the chase (on platen presses) or the base (on a Vandercook).

Step 2. We recommend checking the roller height in the four corners of the press bed. We’ll start in the upper right hand corner. Engage the form rollers and position them over the upper right corner of the bed.

Step 3. You will be pulling a stripe of ink on the round surface of the roller gauge. Pull the gauge underneath the form rollers so that a stripe of ink is transferred to the rounded surface of the gauge’s cylinder. Measure the stripe of the ink: you want your ink stripe to measure 3/32”. If the strip of ink is less than 1/16”, you’ll have difficulty consistently inking your plate (some areas will appear too light, and some areas will appear too dark). If your strip of ink is wider than 3/32”, your rollers put too much pressure on your plate and cause your printing to be chunky/blurry.

Step 4: On a platen press, to adjust the height of your form rollers: add tape to the rails that the roller trucks ride on. You may have to add several layers of tape. Scotch or masking tape is frequently used for this. If you’re using a press other than a platen press, consult your manual as to how to raise your form rollers.

Step 5: Repeat steps three and four in each corner of your press bed.

Step 6: When your rollers are positioned correctly, you should pull identical 3/32” stripes of ink from the four corners of the press bed, and your printing should be both crisp and beautiful! 

If you continue to notice inconsistencies in your inking after adjusting your roller height correctly, you may need to purchase new rollers and, if using a platen press, roller trucks as well.

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This should be a pretty easy process.

First, peel up the old adhesive to remove it. Since the adhesive holds onto the plate strongly, you can potentially kink the plastic backing if you're not careful. We recommend that you lay the plate face down on a flat surface. Hold the plate down with one hand while peeling the adhesive off with the other. Try and keep the plate from flexing inordinately while you carefully tug the adhesive off the back of the plate. The adhesive might tear into pieces, but you can simply pull it up in strips.

Now, put on the new adhesive. Make sure you're putting down the side of the adhesive covered with the brown release paper onto the plate. The side with the pink release paper attaches to the base. When you first mount the adhesive to the plate, start with one side of the plate and roll out the adhesive so that it makes as few bubbles as possible. If the bubbles happen, work them out with your fingers or pierce them, through the adhesive, with an Exacto knife or awl. You should be able to get all the bubbles out at this point.

If bubbles form underneath the plate when you mount it to the base, first try working these out to the edges of the plate with your fingers. If that fails, you can puncture the bubbles by sticking an Exacto knife through the plastic backing of the plate to release the trapped air.
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Instructions for using the stouffer gauge to accurately figure out the exposure time for your photopolymer plates): The Stouffer gauge is a reusable piece of continuous-tone film that you should use to test photopolymer plate exposures. Place the Stouffer Gauge in contact with a 1” x 6” strip of plate material (after you peel off  the plate’s protective plastic cover). Then expose the plate.

You’ll have to guess the first exposure time because that varies depending on the equipment that you use. Start with the exposure time listed on your plate’s tech data sheet. For exposure times, please keep in mind that these times are for commercial photopolymer platemaking equipment. Any alternative photopolymer platemaking devices may have very different times and you’ll have to experiment more to find your ideal time.

Also check the plate's tech data sheet for the Stouffer value you’re trying to hold during exposure.

For example, the 94FL has a Stouffer value of 18. Make sure that the exposure used with the Stouffer Gauge hardens the plate for all the numbers up to and including #18. If you goal is #18, and #19 and #20 start to harden during your exposure time, then your exposure time is too long– decrease the exposure time. If your goal is #18, and #17 hardens but #18 washes out on the test plate, then increase the exposure time.

You most likely will have to expose several different test plates at several different exposure times to find the perfect exposure. Since the Stouffer gauge is small, you won’t waste much plate material in the process.

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Standard Boxcar Base users: The majority of Standard Boxcar Base owners use the 94FL plate. However, some printers find they prefer printing with a harder plate, the KF95. This harder plate gives less distortion than the 94FL on type smaller than 8 points or on thin lines. However, the 94FL holds slightly better detail.

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

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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.

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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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While we only support using photopolymer plates for letterpress printing, there are literally hundreds 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.
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None of the byproducts of processing photopolymer plates are known to have health risks, except if you're allergic to 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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Because processing your own plates is 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 do sell platemakers in various sizes and for various budgets. If you’d rather learn how to hand-process your plates, we recommend taking a class at some of these great book 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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Boxcar Press provides unexposed plates for intaglio and etching artists who want to create prints using a safer and more environmental 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 experimenting with polymer in terms of correct UV exposure, wash out times, creating transparencies, homemade UV light boxes and more.

• “Polymer Photogravure for More Photographic Intaglio Prints” by Jon Lybrook
• Elizabeth Dove, Technical Notes
• “Photo intaglio - an overview, ” Alternative Photography
• " Intaglio photogravure printmaking 1 of 3,” Alternative Photography
• Solarplate Etching how to
• "Possibilities of Polymer Photogravure," by Kari Holopainen
• Ultraviolet Light Box

• Etching and Photopolymer Intaglio Techniques, by Colin Gale
• Printmaking in the Sun, by Dan Welden and Pauline Muir
• Polymer Photogravure: A New Method for Photographers and Graphic Artists, by Taneli Eskola and Kan Holopainen

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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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. 

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. 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 plates in a Ziploc 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 and/or a very small amount of water mixed with dish soap applied to a sponge. Exposure to too much water will cause the plate 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:

• Metal Clay yahoo group: join this vibrant community of over 3,000 artists. 
• Maggie Berman’s site features a great instructional article on using polymer plates for metal clay, PMC, or precious metal clay artists.

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It is best to mix only inks from the same family – oil base with oil base, rubber base with rubber, acrylic with acrylic.

We recommend rubber-based inks for general letterpress printing—it’s the type of ink we use in our own print shop. Use the oil-based inks if you’d like a glossier ink that works well with coated papers (though you won’t be able to leave the ink on press overnight). Try the acrylic if you’re looking for a glossier ink that can still stay open on the press.
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Try our letterpress ink basic starter kit, which includes Printing Black; Flame Red (032); Reflex Blue; Yellow; Transparent White (mixing white); and Opaque White (printing white). If you’re ready for more, you may want to try the remaining Pantone base colors.
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Add magnesium carbonate liberally to your ink. Magnesium carbonate is available from Daniel Smith Art Supply.

With letterpress, we tend to print dark ink on light paper, because that is letterpress printing’s strength! Light ink on dark paper is really best suited for engraving. That said, if you really want light ink on dark paper, just be prepared for paper show through. Letterpress uses transparent inks. Even with opaque white, printing light ink on dark paper will be like using a thin coat of white paint on a brown wall: you’ll see the brown color through the paint. If using a pure white ink or metallic ink, you can run a piece through the press twice to create a more dense color.
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Oil based inks will dry within a few hours if left unattended on press; dried oil-based inks can take a long time to clean and can even cause rollers to be permanently damaged.

To clean ink off your press, we recommend California Wash used with rags or disposable shop towels. This press wash cleans up acrylic, oil based and rubber based inks well, is a low VOC solvent, and has a mild somewhat citrus odor.
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We offer all 15 base Pantone mixing inks. These inks, paired with the Pantone formula guide, will allow you to mix any of the guide’s hundreds of Pantone colors.  The base inks are: Red (023); Pantone Black (mixing black); Blue (072); Green; Transparent White (mixing white); Orange (021); Process Blue; Purple; Reflex Blue; Rhodamine Red; Rubine Red; Violet; Warm Red; and Yellow. We also carry opaque white for printing white or printing on dark paper stock; universal printing black, the perfect black letterpress ink (available in oil-based or rubber-based only); and custom mixes that match any Pantone number. View a PDF of the Van Son color chart.
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Kreene, a flexible and matte transparent plastic, is used in a platemaker’s vacuum frame to hold films against photopolymer plates during exposure. But over time, it’s the nature of kreene to get wrinkled and lose flexibility. When you find that your kreene no longer seals off the vacuum well, it’s time for a kreene replacement! At Boxcar Press, we replace our kreene every two days, but we process a lot of plates. With lower use, kreene can last for several months.

To replace your kreene: cut out a square of kreene to the size of the previous kreene piece (your kreene will be slightly larger than the grooves in the vacuum table). Pull the round bar off the previous sheet of kreene. Afix the new sheet of kreene to the bar with double-stick tape. Lay the kreene in position on the vacuum table and turn the vacuum on. Work out any wrinkles in the kreene so it remains flat. Using double-stick tape, affix the kreene edge opposite the bar to the vacuum table. You can then roll the kreene over the bar and start exposing your polymer plates.

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A platemaker’s brushes wear out after prolonged use: these brushes should be replaced every 6-36 months. You can tell when a brush is tired out because the bristles are matted down. We sell replacement brushes for all of our platemakers: please e-mail or call us to order these.
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Magnetic mounting rubber and rigid mounting rubber come pre-sealed. Over time, this seal breaks down. You can make touch-up repairs with our green die sealer. Apply green die sealer in a thin bead to the edge of the mounting rubber. Let dry overnight.
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Drain the platemaker often (twice a day if you're using the machine all day). To drain, open the drain valve. The washout water is safe to go down the drain. To refill, close the drain and fill with water. Leave the tank full of water so the brushes don't dry out. If you're leaving the machine unused for an extended period of time, add half a cup of bleach to the water to resist algae.
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