Painting Project: Arboreal Abstracts (aka colourful barcodes)

This painting project is about rediscovering the joys of “happy accidents”, of playing with colour, layering and more layering, responding to what’s happened, not working with a predefined outcome in mind but painting your way towards an arboreal abstract . That is, an abstract that’s got strong verticals which you may or may not make look like tree trunks, or stick to it being a colourful barcode.

The starting point for this project isn’t a reference photo, but the colour that reflects your mood today. No one layer or mark is crucial, trust the process (i.e. follow the steps), don’t try to dictate the outcome from the start but meander along towards a finishing point.

You will need:

  • Masking tape
  • A canvas or painting board or sheet of paper that has been gessoed (so the masking tape doesn’t tear it)
  • Any fast-drying paint (watercolours, acrylics, ink)
  • A palette knife or bit of stiff card
  • A spray bottle of water
  • Paper towel
  • Optional: texture paste

(You can do this without masking tape, using strips of card or paper instead to mask off areas, but you have to work more carefully so as not to move these thus counteracting the aim to paint loosely with colour without worrying about what’s already painted.)

What to Do

Step 1: On the back of the canvas or sheet, draw an arrow from the top edge to the bottom. This is simply to remind you which direction to paint the stripes and to put down the masking tape. If you’re gessoing the surface, do it in in the direction of this arrow, from top to bottom.

Step 2: Pick a colour that reflects your present mood. Any colour, bright or muted, light or dark; there’s no right or wrong choice. Paint seven stripes from top to bottom edge — do it freehand, eyeballing it, no measuring or taping. Any width, any distance apart. Do it fast, don’t overthink it’ there’s no right or wrong, and then quickly move onto the next step.

Step 3: Take the palette knife, or bit of card, and pull it across the paint horizontally, spreading out sections that are still wet. You might spray some water onto the surface to encourage it to spread a bit. Stamp up and down with the palette knife too, to ‘print’ random shapes of colour. Don’t stress if it looks a chaotic mess; it’s allowed to, and probably should.

Step 4: Pick another colour, a transparent one not opaque (for transparent: think “stained glass”) and do the same again (steps 2 and 3). Don’t worry about whether the colour already down is dry or not.

Step 5: Pick another transparent colour and, using a thinner brush, paint 11 narrow stripes from top to bottom edge. Mix in some opaque colour or white into this colour, and paint another set of narrow stripes.

Step 6: If you still have any areas that are blank canvas or paper, paint over these with any transparent colour. I suggest a yellow or light blue.

Step 7: Wait for paint to be dry to touch.

Step 8: Place masking tape from the top to bottom edges, leaving at least five stripes to paint. Try to ensure they are not evenly spaced like fence posts; overlapping pieces of tape helps avoid this.

Step 9: Pick a dark transparent or semi-opaque colour, and paint in the sections between the masking tape. Brushing from top edge to bottom rather than sideways helps prevent paint from seeping in beneath the tape. Though it doesn’t matter if it does; don’t bother to ‘tidy it up’. If you can’t decide what colour to use, I suggest a purple. Don’t obsess about getting the paint even across the length of the stripe, variation adds visual interest.

Step 10: Move the strips of masking tape to create another series of stripes, and paint these with a different transparent colour.

Step 11: Move the strips of masking tape again, but this time we’ll use an opaque colour. If this is all testing your patience and you want this to be the last set of stripes you do, pick white. Paint along the stripes.

Step 12: Dilute another colour (some black or Payne’s grey if your stripes are white) so it’s fairly fluid and flick it along the stripes to create random dots. Maybe do it with another colour too. Work fast as you next want to take a rigger brush or the palette knife and pull this horizontally across the painted stripes — where the dots are still wet they’ll become little horizontal lines.

Step 13: Do steps 11 and 12 with white as the base colour of the stripe if you didn’t use it last time.

Step 14: Lift all the tape and ponder the result. Decide which is the right way up.

It might all be working very well already, it might need a few more rounds. Think about whether you might use some transparent colour to darken any sections, as well as opaque colour to lighten sections or hide parts. I usually leave it overnight and then do another round of stripes the next day because I find it “wants more”. Don’t stop too early, the more transparent layers you do, the richer the colour becomes.

TIP: If it feels too bitty or has all gone awry, paint over the whole thing with a transparent dark — I like a purple — which will unify it as well as darken everything slightly (rather err on the side of having your transparent dark too dilute and do another coat than go too dark, you just want it to subdue everything a little not obscrue it). Wait for this to dry and then add a layer of opaque stripes on top.


  • Use texture paste on some of your stripes. I would apply it with a brush working horizontally so the paste has lines across echoing tree bark.
  • Use iridescent colours — gold, silver — in the background or on the stripes.
  • Pick only “ugly colours” or your least favourites.
  • Unexpected colours, especially in in the lowest layers.
  • Flick or brush colours onto the stripes at every step.
  • Use the pipette from an acrylic ink bottle to draw lines, then spray with water to get the paint to spread.
  • Brush a transparent dark down one side of the stripes will give a suggestion of the curvature of a tree trunk (form shadow as the trunk curves away from the light).
  • Work on more than one painting at the same time, using ‘leftover colour’ from the one on the next and a unique colour in each. This helps being impatient waiting for paint to dry so you can reposition the masking tape.
30x30cm, acrylic on wood panel: Autumn, Summer, Winter

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