The Dark Arts

How does letterpress printing happen, you might wonder. How does it work?

Most of us only see printed images appear fully formed, sliding smoothly out of the 'black box' of a printer or copy machine. The physical process of any kind of printing can seem mysterious, so here's a little intro into the dark arts of letterpress.

Meet the clamshell.

Very basically, the type of letterpress I use, called a platen press, is like a huge, heavy, metal clamshell.

Paper to be printed goes on one side of the shell. An inked 'form' (meaning the raised artwork or text you'll print from), goes on the other, and the two halves of the clamshell get closed up by the press really really hard. The raised letters and/or artwork meet the paper and push into it, making an indent in the paper and leaving ink behind. Viola! An image.

The process is kind of amazingly simple, and at the same time, it requires a lot of experience and skill to print things well. Why? Well, for one thing...

The big metal clamshell doesn't care about OSHA.

These presses were designed a long time ago in an era with very different attitudes about health and safety precautions. There was no OSHA back then, for sure. It was your job, not the machine's, to keep your fingers intact. There are a lot of moving parts to the press - and pretty much just your own constant awareness of where you're putting your hands to keep you safe.

I don't mean to make it sound scary - I just want to convey that letterpress printing requires a more intense focus than you might think. When people see someone in the middle of printing, the press spinning smoothly and rapidly along and the printer rhythmically putting paper in and removing prints, they often say, 'That looks so soothing and relaxing.'

Actually, no!

It is fun and satisfying, yes, but I wouldn't call it relaxing. When I'm printing I'm very carefully watching where my hands are at all times - and I'm also watching the quality of the printing which, this being a very un-automatic un-digital process, depends on lots of micro-adjustments made by the printer to make things consistently print well.

So, shall we print something?

First we mix up some ink.

I dirty a lot of ink knives, that's for sure.

Then, we put the ink on the press.

The press has a cool spinning metal disk which holds the ink supply. I put slashes of ink on the disk, then run the press for a bit without printing anything to let the rubber rollers run up and down across the disk to spread the ink into a uniform very thin layer all over the disk.

As you can see, you can only print one color at a time. Each color is a separate press run.

Lock it up. 

After the press is all inked up, I lock up the artwork I'm going to print in a heavy metal frame, called a 'chase' so I can put it in the press. The chase is the dark metal outer frame with handles in the photo below.

I usually print using polymer plates made from my drawings (more on that whole process in a later post). The polymer plate is the thin transparent sheet above with yellow lines on it.

These yellow lines (or shapes or text) stick up high enough above the rest of the plate to be inked by the press rollers and then print onto the paper. 

Adhesive on the back of the polymer plate sticks it to a metal base underneath. Pieces of wood and metal are put around the metal base to fill the whole length and width of the chase, and then everything is tightened up so that when I pick up the chase to put it in the press, everything *holds together* in the frame rather than falling out in pieces all over the floor. (That would be bad.)

Make it type high.

The press was originally designed to print from metal type, but any raised artwork or text that is reasonably durable, like a woodcut or linoleum cut (or my polymer plates), can be printed on a letterpress as long as it is 'type high', meaning *exactly* the same height as metal type. The metal base under my polymer plate is what makes my artwork type high and printable.

Get ready to make ready.

Next we pick up our locked-up chase and slide it vertically into the press. You can see it below - it's in the back half of the big clamshell, just under the ink disk.

Printing is a little bit like painting a house - the prep time takes a lot longer than the actual painting does.

With letterpress printing, that prep time on press to get a good clean print is called 'make ready'.

You have to get a few things dialed in:

Ink volume: Printers can tell roughly how much ink is on the press by the sound of the rollers going over the disk. Yup, it's that analog. The louder the hiss the more ink is on the press. The larger your text or areas of artwork, the more ink you need to get good coverage. And you have to be careful not to over-ink the disk if you have finer lines and smaller text. A balancing act for sure!

Registration: Adjust the paper guides to get your paper located at just the right angle and location so that your design prints perfectly straight and orthogonal on the paper.

Pressure: Solid areas of ink and large-scale text need more pressure while areas of finer texture, thin lines or small text need less. Pressure is controlled by how many layers of thin 'packing' paper you put behind the sheet of paper you're printing on. 

Like everything in letterpress, getting the packing right is a very low tech process. You build up layers of packing in areas that are printing too light until everything looks evenly inked and the coverage and depth of impression are even and spot on.

Phew! Now you're ready to print away!

For each color in your design, you clean the press and start the process all over again.

Here you can see the color progression of printing our Vine Thank You design, which has three colors, meaning it goes through the press three times.

Ta-dah! It's ready to be trimmed down to finished size, and then you're done! Well, ok, then you score the cards where the fold will go so you get a nice smooth fold - and THEN you're totally done.

You may be thinking - letterpress printing is it a lot of work! Yes, it definitely is, but it has a warmth and texture that no other printing process does.

And it's fun (the vast majority of the time!) to figure out all the variables to make something print well and see the design emerge, color by color, using this durable old cast iron machine.



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