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Making digital cutting files for stencils from simple drawings

This post would probably have been better coming before Part 1. It was initially intended to be a single post, but grew too long. It covers ways to make cutting files for stencils from very simple drawings, using a digital cutter like Cricut.

Software

You will need some sort of photo editing software, but it doesn’t really matter what it is. My examples use Paint Shop Pro (abbreviated from now on to PSP) on a Windows PC, because that’s what I’m familiar with. Options include Photoshop Elements, Affinity Photo, Corel Painter Essentials or any of a myriad phone apps. You’ll need to find for yourself the equivalent tools to the ones I describe. You will also need software to convert the graphic file into a suitable format for your cutter. I will not be addressing that aspect.

You do NOT need to spend large sums on the full version of Photoshop, unless you are a professional graphic designer, in which case you know more than me…

My interest is in creating non-repetitive stencils rather than overall patterns, but the approach I use will also work for the pattern stencil.

Step 1 – create the image

Creating the cutting file for your stencil starts with a sketch design. Use a dense black pen (something like a Sharpie works fine) on white paper. Remember that completely enclosed shapes like rings will not cut properly unless you include a bridge link to the supporting material. Think of the difference between an O and a C. If you cut the outer edge of the O, the inner shape will also drop out, leaving a solid circle. Later, I’ll show you ways to check for areas where this might happen and some tools for avoiding it.

Once you have your sketch, you need to get it into the software. I simply take a photo on my phone, because I’m using freehand sketches and don’t need accurate geometry. If your design is more intricate, such as a Mandala, you will need to take care to keep your phone parallel to the image and ensure even illumination. You can scan it if you have access to a scanner, or you may prefer to do the sketch digitally. This might be a good option if you are working on an iPad/tablet or if you have a graphics tablet.

In my case, working with an Android phone and a PC, I’ve found the easiest way to get the file into my editing software is to share it from the phone to a folder in the cloud such as on Dropbox. Again, use whatever method is most comfortable for you.

Phone photo of simple line drawing with a sharpie pen
Simple line drawing with Sharpie.

Step 2 – resize the graphic image

Once you have the image in your editing package, you need to ensure it is big enough to create a cutting file. My phone produces .jpg files at 72 dpi. My cutter is a Cricut. The Design Space software works at 90 dpi. I simply resize using PSP to produce a file that will print to a maximum of 12” x 12” at 90 dpi. The normal constraints about pixelation are not an issue because this is largely removed on conversion to an .svg file for cutting.

Resizing in PSP

From the Menu select Image, then Resize – select ‘by size’ button and set the size you want, then set resolution at 90 pixels/inch. Ensure that the ‘Resample’ box is selected. If you want to change the proportions of your image, e.g. to convert from rectangle to square, then be sure to unselect the ‘Lock Aspect Ratio’ box. You can use this option too if you tried to create a specific aspect ratio, but you ended up with perhaps 11.5” x 12.1” instead of 12” x 12” or 7.3” x 4.9” instead of 7” x 5”.

Step 3 – convert to black and white

The next step is to ensure the image is just black and white, with no grey shading. In PSP, there are several ways to achieve this. The simplest is to reduce the number of colours to 2.

In PSP Menu – Image/Decrease Colour Depth/2 Colour Palette.

If your lighting is uneven, then this may translate into black areas which should be white. An alternative that usually avoids this is the ‘Threshold’ command, which is my preference.

PSP Menu – Adjust/Brightness and Contrast/Threshold. This brings up a slider control that allows you to fine tune the breakpoint between black and white. You’ll have to find the sweet spot for your particular image yourself.

Sharpie drawing after threshold command

You now have a version of your sketch in pure black and white. If you see odd black marks where they are not supposed to be, just paint them out in white with the brush tool from the icon bar on the left-hand side. Depending on the density of ink in your pen, the lines may not be continuous. You can test this by infilling each shape with a colour (assuming you used the Threshold command.) You can do this by selecting the icon on the left that looks like a paint-can tipping over and picking a colour from the palette on the top right. Then click inside the shape you want to fill. If a line is broken, something like this happens.

Effects of a break in a line

You can reverse this by undoing the fill command using Edit/Undo, or by infilling in white again. Both will take you back to the ‘Threshold’ version above.

Step 4 Fill in any line gaps

Your next step is to fill in any gaps in the lines. You need to zoom in and look for them. If there are only a couple of breaks, use the brush or pen tool to draw across the gap. If the lines are very broken, try using a command called Erode Edges first.

PSP Menu – Effects/Edge Effects/Erode.

This makes the lines less crisp and fills in minor gaps. If you still see gaps, you can repeat the command a couple of times

PSP Menu – Edit/Repeat or from the keyboard Ctrl+Y

Keep testing by infilling each space to see if thee are still leaks. At some point, it will be simpler to draw across any remaining gaps.

Your aim is to end up with lines that are continuous and allow each space to be infilled without any ‘spill over’. Once that is achieved, reduce the colours to 2 again.

Step 5 – prepare the cutting file.

Begin by creating a negative image from your file.

PSP Menu – Image/Negative Image

If you look at the example and think about how a stencil works, you will see that eventually you will be cutting out all the spaces surrounded by lines. This is easier to visualise if you swap the two colours over. The negative image however is now black around the outside of the image and this is not to be cut away. It needs to be turned white again with the ‘Flood Fill’ tool, giving you the image on the right.

You can stop at this point and use this to prepare the .svg file for your cutter, or you can manipulate it further. For example, the image as it stands still has the rough edges to the line created by the ‘Erode’ command. Leaving these in, gives an interesting effect when cut, but also increases the time it takes to cut.

Further options

There are two options you can consider here. They both have similar effects, although not identical, so have subtly different outcomes. The first is an Edge command called ‘Dilate’ This has the effect of shrinking the black shapes slightly by somehow drawing back the line edge. This can create pixel sized gaps that might need touching in with the brush tool. The other command is called ‘Median Filter’ As the name suggests, this smooths the edge by averaging it out. It also enlarges the white gaps between shapes and rounds off corners. The intensity of the effect is controlled by a slider. Both can be applied repeatedly or sequentially, with subtle variations in the outcome. Try them out to get the effect you like. Remember, if it doesn’t work, you can back out with Ctrl+Y.

PSP Menu – Effects/Edge Effects/Dilate

PSP Menu – Adjust/Add or Remove Noise/Median Filter

Rounded edges after use of median filter

Cutting the stencil

To cut the stencil, the .jpg file needs to be converted to .svg format. I do this using the free program Inkscape. I won’t go into that in detail here. The .svg file is then loaded into the appropriate software for your cutter. Again, I won’t go into detail on that aspect.

Your views

This is a long and quite detailed post. I’m sure there are other ways to achieve the same ends. Let me know in the comments if you have done this in other ways or if you find any errors. Menu commands for PSP are as used in the 2021 edition.

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Making stencils for gel printing with a digital cutter – part 1

This is the first of a planned series of posts about making stencils for gel printing using a digital cutter. In my case it is a Cricut Maker, but the principles are general.

Making colour separations

These stencils came out of some thoughts I had about making silk screen versions of my gel prints. I was hoping to use colour separations. This is the process by which original full-colour digital files are separated into individual colour components for four-colour process printing. Every element in the file is printed in a combination of four colours: cyan, magenta, yellow, and black. This is known as CMYK in the world of commercial printing and in silk screen printing. This isn’t an original idea, of course. Anyone familiar with Matisse will almost certainly be aware of his stunning cutouts, but may not be aware that they were also published in silk screen versions.

I began with a scan from one of my prints. I created the CMYK colour separations with Paint Shop Pro (from now on PSP). Unfortunately, I no longer have access to screen beds, so this is currently not an option. In practice, I don’t think I’m fit enough any more, to spend several hours pulling ink through the screens. However, having already used scans of pen drawings to make stencils, I decided to experiment with these separations. The print I’m using here is called ‘Area 52’, available from my shop.

The image below is an example of one of the colour separations. This is from the magenta colour channel. In this form, it clearly can’t be used directly to make a stencil suitable for gel printing.

Magenta colour separation from original image file. Not suitable for making stencils in this form.
Magenta colour separation from original image file

Simplifying the file

To create a version that can be cut as a stencil, it needs to be much simplified. I did this using various tools in PSP, which led to this. (More details of the process by which I did this, will be in later posts. If you can’t wait though, get in touch and I’ll try to help.)

Simplified magenta file suitable for making stencils
Simplified Magenta channel

PSP allows me to digitally recombine these simplified images, which led in turn to this image. This is closer to what you would get with screen printing, but is useful to visualise the outcome.

Digitally image from recombination of simplified image. Simulation of effect of using stencils made by digital cutter.
Digital image created from recombined and simplified channels

Be flexible

However, just because a file is called magenta, doesn’t mean that it has to be used that way. PSP allows me to digitally recombine the image files in any order. With four files to combine, there are 24 possible combinations, so this one below is just one. It helps to make a point though. When the stencils are cut and used to make gel prints, you have complete freedom in the colour you use.

Digital image created by shuffling colour separation files when recombining. Simulation of effect of using stencils made by digital cutter.
Image created by recombining channels in different order.

In the real, as opposed to the digital world, there are other variables. Varying the opacity of the paint used, and varying the order in which you use the stencil, will also give different results.

Finally, just as an experiment, here is a combination image using CYMK files from two different images. I’ve included it just to make the point that once you have the stencil you have complete freedom in their use.

Abstract Digital print in bright colours
Electric Avenue – limited edition digital print

In many ways, this last image is analogous to making a collagraph print from multiple plates. I have experimented with this many times in the past.

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Gel printing – my approach

Multi-layered Gel print

I’ve tried to record the process of making one of my gel prints several times, but without success. This is because my working methods mean I am usually working on perhaps a dozen prints at once, jumping between them. I build up each image over time by adding layer after layer of colour and texture. The closest I have come is a series of photographs of different stages. This post tries to fill some of that gap.

Applying the paint

All gel prints start with paint on the plate. This is the first big variable. I apply the paint with a brush, a roller and even my fingers. Rollers give the most even effect. Even then as the roller loses paint to the plate in one place it can start picking it up elsewhere. The basic aim is to create variations in the thickness of the paint sitting on the plate. This helps to create variations in colour and visual texture in the eventual gel print.

How much variation you want is a matter of choice. For me, early layers tend to have more or less complete coverage using a limited palette. For later layers I may only cover part of the plate, perhaps using a mask or stencil. On any layer, I can create textural variation by applying anything with texture to the paint as it sits on the plate. I use pill packets, bits of card, pieces of scrap plastic with interesting textures or just crumpled paper. I often remove paint completely with cotton buds.

How this will print depends on a range of factors – what colour is it going over, on the use of opaque or transparent paints and on how much is left in the thinnest areas. Using more than one colour at a time on the brush or roller also creates variations and colour blends. Adding acrylic medium also alters things.

Layering

I don’t clean down the plate between every layer. Because the transfer from plate to paper is not always 100% this can leave patches of paint behind. Rolling fresh colour over these patches often picks them up and transfers them to the print, adding texture.

Using transparent paints in a layer will shift the colour underneath depending on the two colours used. If the upper layer is partial this will leave the underlying colour untouched in some areas. Removing part of a layer also allows the underlying colour to come through. The effect will vary between transparent and opaque colours.

I also restrict the area to which I’m applying the paint using masks or stencils. I usually cut or tear these from newsprint. Opaque paint will obscure what is underneath. I do this to simplify messy areas or perhaps to combine separate blocks of colour. Using transparent or semi-transparent paint can subdue contrast between adjacent areas or shift colours by mixing through layering. Acrylic medium can create translucent effects if you mix it with opaque colours.

Eventually the build up of paint on a plate makes the transfer of paint to the print too unpredictable. This is my cue it needs cleaning. The paint left on the plate won’t be wasted however, even if it has dried completely. Start by rolling out an even coat of colour over everything. Then start to take the print as normal, but leave the paper on the plate longer than usual before you lift it. If everything goes well the last layer has bonded with the residue on the plate and most of it will transfer to the paper. You are unlikely to get a print this way that stand in its own right. The idea is just to use it as the first layer for a subsequent gel print.

As the layers of paint build up I look for the happy accidents and try to reinforce them. It is the way that successive layers show through that creates the subtle colours and textures which I think are the defining characteristic of gel prints. Some paints are opaque, other transparent. It is very rare for me to plan out an image. Even when I do that plan is often quickly abandoned when I see something unanticipated but which works! Eventually I get to a point where, as I look at an image it says Stop! That is something I can’t define. IT seems to be a combination of visual balance in terms of shapes and colours and overall cohesion/balance of the image as a whole.

Composition

Building up the image in layer after layer makes adhering to a specific composition difficult. I rarely have a fully planned composition in mind. Even when I do, that can be derailed when something unexpected happens which I like. The closest I usually come is the use of very simple structures like this crib sheet of mine. The artist Bob Burridge produces a rather more refined version you can buy.

Compositional diagrams
Set of compositional diagrams

A final thought on colour

As you add layers to your gel prints, you need to consider not just the area to be printed but the colour you will use. Careful thought here will give you more control over the final image. The first thing to do is to get a colour wheel. If your first layer is pretty much all cadmium yellows, look on the wheel at the colours either side of yellow. Using these colours for subsequent layers will give you a final image which is harmonious and balanced.

Alternatively look on the wheel at the colour opposite yellow – the complementary colours. Don’t just look at the direct complementary, look at the colours on either side of it which form the so-called split complementary. Some wheels also include markings for colour triads and for four colours. Try them. Using these colours will add drama and intensity to your work.

Don’t make the assumption that you need equal areas of complementary colours. Sometimes a large area of a relatively low-key colour can be balanced by a small intense area of its complementary. Think also about the effects of using transparent layers of one colour over its complementary. Think about how the effect differs from using opaques colours side by side. This can have an impact on your composition too.

Examples of my gel prints

There are lots of examples in the shop in the Lockdown Series 2020 and many more in my Instagram feed.