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How do I print with light toned letterpress inks on dark paper?

With letterpress, we most often 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 to show through. Think “chalkboard” for the end results. 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, you can run a piece through the press twice to create a more dense color. Metallic inks will be more opaque and are the most popular choice for paper cover-up with dark papers.

How do I firm up my thin letterpress ink?

Add magnesium carbonate to your ink. Magnesium carbonate is available in our Supplies section from Boxcar Press.  Inks are measured by their tackiness or stickiness and their body or how stiff it is. An ink’s body can be drippy like chocolate syrup topping or thicker like frosting or paste.  The ink can also be described as being long or short.  Long inks are tackier and when pulled up straight from the can will have a long tail.  The white powder of magnesium carbonate will stiffen your ink and reduce tackiness.

What letterpress ink should I use: oil base, rubber base, or acrylic?

We recommend rubber-based inks for general letterpress printing—it’s the type of ink we use in our own print shop. Rubber-based inks dry by being absorbed into the paper. That makes them ideal for the cotton and bamboo blends of paper used in letterpress. Use the oil-based inks if you’d like a glossier ink that works well with coated papers . Oil based inks dry by oxidation or air drying. That is why they can form a skin on the top of the can after opening and why you won’t want to keep it on your press overnight. Try the acrylic if you’re looking for a glossier ink that can still stay open on the press. Acrylic inks will also harden in the can quicker than rubber-based inks so long term storage can be a factor.

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

Tell me how to put new adhesive on an old letterpress plate.

If you start to see gunk stuck in the adhesive (cat hair, human hair, your lunch crumbs, etc.), then it’s time to put new adhesive on your polymer plate. This should be a pretty easy process but does require a little muscle.

First, peel up the old adhesive to remove it. You’ll need some good fingernails to get between the adhesive and your plate. 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. If you have purchased a 12” x 18” sheet of adhesive, lay the blue release paper on a flat surface and have the brown silicone paper side face up. You will remove this silicone paper to show the sticky adhesive. If you have a roll of adhesive, pull out or unroll the adhesive so the sticky side is face up. When you first mount the adhesive to the plate, start with one side or corner of the plate and lay down the plate to the adhesive so that it makes as few air gaps or bubbles as possible. If the bubbles happen, work them out with your fingers or pierce them, through the back of the adhesive, with one prick of 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 BACK of the plastic backing of the plate (the blue side) to release the trapped air.

Can I lock up two different Boxcar Bases and use them together?

Yes, you can certainly lock up two Boxcar Bases into one chase and print, and in most situations print a letterpress plate that spans the two bases. We inspect our Boxcar Bases and verify they are within plus/minus 0.001” in thickness, parallel and flatness. Still, we’d like your bases to be even closer in height than +/- 0.001″ if possible.  Here’s how to do this depending on your situation.

  • You purchase one base and have it cut into two pieces: use each piece individually or lock them both back up together for a larger base surface. Your two cut sides should match up perfectly. Slide them together and using quoins, furniture and leading, fill the chase on all sides around the two bases to support the pieces and have a good strong lock-up.
  • You already have two different bases in your shop: These should be fine to print. There may be slight variation within the +/- 0.001″ tolerance, so find the two sides most similar in thickness and slide them together.
  • You have a base. You want to purchase another base to print with at the same time: We keep detailed specs on each base we sell. When you order your second base, let us know your original base’s serial number—we’ll make sure the bases we ship to you are identical heights so you can butt them together and have a very even printing surface.  Where do you find your serial number – on the bottom edge under the Boxcar text.
  • You are going to purchase two bases to print with at the same time: Just let us know that you’re planning to print with them at the same time, and we’ll choose the two closest in height from our inventory.

Is there a checklist for me to review with my files before submitting to platemaking?

To ease file prep woes and to ensure a smooth production transition from file to plate, it is a great help to all to give your files one last review before submitting them. The first few things to make sure is that your file’s artwork is set to the right dimensions, that you’ve checked your artwork to make sure all plate type line minimums are met, that your file is in the proper color mode or image mode and that your file is in the proper file format and extension.

When working with a file that requires multiple colors for separations, please make sure all objects are assigned to their appropriate Pantone swatch or spot color. Adobe Illustrator and InDesign are excellent programs for setting up and checking such files.

Please also remember to check out any other file prep questions to answer any unresolved questions that you may have.

If I’m scanning an image, what resolution (DPI) should it be?

Most folks want clean line art, and if this is what you’re seeking, scan at least at 600 DPI, though 1200 DPI is even better. Open your scan in Photoshop to convert your file to the Image mode of Bitmap via the 50% threshold method and an output of 600 – 1200. If you lose too much detail, you can make adjustments to your image by using Image Adjustments > Levels or Image Adjustments > Brightnesss / Contrast.

If you’d like a halftone, you can use a 300 DPI scan. With halftones, keep the image in the grayscale color mode in Photoshop, and let us know the LPI / line screen.

Either way, save your image as a TIFF with LZW compression. This will make your file size more manageable when placing into another program like Illustrator or uploading to your job ticket.

Is there a preferred LPI (Lines Per Inch) for halftones?

The ideal LPI depends on your paper and presswork, but most printers printing on uncoated paper use a 100 LPI. It’s a good balance of fine screen and easy printing. The higher the line screen, the more difficult it will be to print, because the high line-screen plate plugs up with ink in the shadows and looks murky over-all. Some printers prefer playing it safe and order 85 or 65 LPI. Using a lower LPI does make the dots coarser and more obvious. The finest line screen that we usually process is 133 LPI, although we would even question the use of 133 LPI, except on coated or hard papers.

If you’d like a halftone for your image, don’t adjust or apply an LPI in your file. Just tell us what LPI you’d like us to use, and we’ll take care of the rest.

If you tell us the paper, the type of press you’re using, and what you hope to accomplish with your halftone, we would be happy to recommend a line screen for you!