One of the most common issues we face here in the Platemaking Department at Boxcar Press is determining a sufficient line thickness. Making that ruling means explaining to customers two things – how do you go about checking to see if lines or text are thick enough to hold on your particular plate? What’s the thinnest line that can hold on the plate?

Surprisingly, there’s just one tool you need to utilize in either Adobe Illustrator or InDesign: The Line Tool. If you are using Adobe Photoshop, the Line Tool unfortunately reverts to a minimum line thickness of 1pt. If you are only using Adobe Photoshop to create your file, we highly recommend placing your final file in InDesign and using the Line Tool to check your work.

What do we mean when we talk about our line thickness guarantee? Simply put, if your lines meet or exceed the line thickness as outlined below, we will guarantee they will hold on your plate. If they are under that thickness, it’s hit or miss. Some days you are lucky and other days, you might lose details.

The first thing you need to determine is your line thickness based on your plate type:

- If your plate type is the KF 95, Jet 94FL, or 94SB, you have a line thickness guarantee of 0.25pt or thicker.

- If your plate type is the KF152, 152SB, or 145SHSB, you have a line thickness guarantee of 0.35pt or thicker.

- For all plate types, your dots (like the ones above the letter “i”, periods, or dotted lines) must be 1pt to 1.25 pt or thicker.

THINK FAST! Quick quiz here – what is usually the most common culprit of too thin lines? Crop Marks! More on that later.

Here’s how to use the handy Line Tool to check to see if your lines are thick enough (and plate friendly, too):

You need to first open your file in either Adobe Illustrator or InDesign. We’ll be using a small type sample in Adobe Illustrator to check to see if our lines are plate-friendly for a KF152 plate type. The KF152 plate type has a line thickness minimum of 0.35pt for lines and 1pt to 1.25 pt for dots. We can see that it looks like there are some thin lines in the serif of the Didot typeface… but will they hold?

First, click the Line Tool icon in the tool palette on the lefthand side of the screen in Adobe Illustrator to activate it. If you cannot find it, hover your mouse over the icon that looks like a line to see “Line Segment Tool (\)” pop up in a yellow box .

Next, in the control panel up at the top, we’ll select the words “1 pt.” in the dropdown area next to the word “STROKE” with our mouse. You’ll be substituting the “1 pt” and replace it with “0.35pt”.

We’ll select the Zoom tool (Z) and move in because we’ll be doing some close up viewing in the area you are inspecting. Select the line segment with your mouse and move it so it is right next to the bottom part of the “L” in “Letter”. Draw a short line so it is parallel with the thin line you are checking on your art board. It doesn’t have to be very long but this little line segment will be our “ruler” to compare thicknesses.

At this close magnification, we see that our line segment set at 0.35pt is much thicker in comparison to the thinnest line in of the serif on the letter “L”. We will need to add a hairline stroke to boost our text’s thickness to correct this.

To add a stroke, using the selection black arrow tool (V), select all the characters in the word “LETTER.” In our Control panel at the top our screen we should see that the letters only have a fill and that we’d like to add a hairline stroke (about 0.15pt). Click the white area next to “STROKE” to activate the area so we can type in “0.15pt”. Immediately single-click the white area anywhere on the board. This will deactivate your selected text and add the hairline (0.15pt) stroke.

Zoom in again using the Zoom Tool around the line segment we created with the Line Tool and the letter “L”. We can now visually see that the serif on the “L” is as thick as the 0.35pt line. Success!

Delete your line segment and zoom back out. Continue around your artboard to visually check to see if other areas look “safe” as well.

For dots, such as the ones around the heart shape, we’ll need to set our Line Tool weight to “1pt” just to be on the safe side. We’ll repeat the same steps mentioned above to create the line, to zoom in, and visually compare the dots’ diameter against the 1pt line segment we just drew on our art board. Like the thinner lines on the “L”, we’ll need to correct this by adding a much thicker stroke of 0.3 pt to boost our dots’ diameter up to 1pt.

Using the Line Tool to check your work should be a “Must Do” test before submitting your files to your platemaking ticket. If anything appears too thin, you will need to correct it.

A few final instructions to help you be aware of potential trouble spots:

-When creating crop marks in your files – the program default setting is often 0.2 pt or 0.25 pt. Keep this in mind so you can make the necessary changes to your crop mark thickness when you place them.

-Thin lines that curve, particularly in wispy script or calligraphic fonts, are always suspect for being too thin. Give them the support they need to hold on the plate with hairline stroke (if needed).

Stay tuned, letterpress lovers — next we’ll solve the mystery of how to create multiple color files!

Related Blog Posts

Learn to Love Color Separations – A Boxcar Press Checklist
Did You Know That … 100% CMYK Black Is a Breeze?

Are your polymer plates starting to curl at the edges?

Like our skin, plates can be affected by the weather and age. When humidity levels are low, the plates can look and feel brittle. And with the passage of time, the thinner polymer on the edges of the plates are pulled towards the denser polymer text and images on the front which causes curling. There is a natural aging of the plates as they do have a limited life expectancy but we can offer a few simple steps that can hydrate and give extra life to your plates.

Printight, maker of Toyobo plates KF95 and KF152, offers these suggestions if you have a platemaking system. Boxcar also gives similar steps for the majority of you who are without such equipment.

1. Place your plate back in the washout system for one minute or immerse in water. We suggest room temperature for a quick dunking, a minute may only be necessary if your plates are severely curled.

2. Sponge off the water and place back in the drying oven of the platemaker for 5-10 minutes. We also suggest, alternatively, a hair dryer to warm the plate and make it more pliable (placing your plate in a box and blowing the hair dryer into the box will keep the warm air more contained).

3. After the plate warms and starts to uncurl, place the plate in its bag and set a heavy object on it to keep the shape.

This should help your plates relax so you can adhere them to your base for additional print runs. Some warnings for you – take care to avoid putting your hair dryer too close to the plates and be patient as warming the plates takes time. And watch that you don’t handle them too roughly after the wash and during drying so your relief images don’t chip.

Store your plates flat. One last tip, you may have to check your adhesive backing to determine if it needs to be re-applied to the back of your plate for a secure hold on your base.

If you have some storage and uncurling tips, tell us about them so we can share. It’s great when we can all learn from each other!

Greg peels a plate off the washout unit on the platemaker. In the water are brushes that have taken off non-inking areas of the plate.

Here is a piece of Harold’s metal cut ( or illustration ) collection: A bride in classic form.

In case you haven’t heard, Boxcar has a recycling program for plastic-backed photopolymer plates called Boxcar Press Photopolymer Plate Recycling Program or BPPPRP. Learn more about this recycling program here.

Inside this formidable cabinet lies a plethora of plate types that one can order from us. You can choose metal or plastic backed, and a variety of plate heights.

Today’s job is a double-sided trifold wedding program. This lovely classic piece is printed in taupe ink on white Smock bamboo paper. Next the program will go on to be scored for smooth folding. Then it will be trimmed, inspected, packed and shipped to the happy couple. That makes us happy.

In pre-press, King Tut stands guard over the imagesetters, helping wand off unruly files.

Here is a plate being proofed in the platemaking department- a test print to make sure everything appears properly. This is a KF152 plate. We make a variety of plate types in different thicknesses, in metal or polymer depending on the customer’s plate mounting system.

by Carrie Valenzuela, letterpress printer. 1:38 p.m.