Introduction: Thermochromic Painting

How to create your own interactive painting ? Well this article is made for you !

I will explain how you can use a thermochromic powder to create a painting with parts revealing only with heat.


Cf: Step 1

Step 1: List of Tools and Materials You'll Need

  • 1 Sheet of a mixed media paper, size A2.(16.5x23.1 inches) : a paper bulky suitable for acrylic painting, gouache, ink, dry or oil pastels, collages and dry technics.
  • Scissors
  • Pages of different books
  • 1 Print of a nebula, size : 8,27 x 11,69 inches
  • 1 Print of a message you want to hide under the thermochromic paint
  • 1 Print of your reference picture, size : 8,27 x 11,69 inches
  • 1 Imitation gold leaf
  • 1 Matt varnish glue
  • 5 Acrylic paints : white, black, blue, pink and purple
  • 1 Eraser
  • 1 Ruler
  • 1 Pencil
  • 1 Charcoal
  • 1 Black thermochromic powder
  • 1 Matte varnish spray
  • 3 Brushes
  • 1 Black pen (a black POSCA if you have)
  • 1 Photo frame (you can choose your size, but it's better if it's bigger than your canvas)
  • 1 Charcoal and pastel fixative

Step 2: Background Conception : the Bonding

Let's begin by the background of your canvas. Take one sheet of a mixed media paper that we'll call "canvas".

1. Glue the books' pages

Rip off some pages, i used 16, from various books and make sure the ripped side is cut straight. Apply glue on a page and stick it on your canvas. Continue this way until all the canvas surface (16.5x23.1 inches) is covered.

2. Glue the Nebula

Tear up the nebula print into chunks and stick to the side of your canvas with varnish glue. Stick as much pieces as you want but don't use too small ones, you want to still be able to figure out what they represent.

3. Stick the gold leaf

Stick the gold leaf by applying the varnish glue on your canvas with a paintbrush and carefully place the leaf on it. Press on it with your hand some seconds, brush the leaf with your paintbrush and to make it crumble a bit.

  • Duration of the step : 45 min
  • Let it dry for 2 hours

Step 3: Background Conception : Customization

1. Prepare the painting

Dilute your acrylic colors (blue, purple and pink) in a cups of water : one cup for each color. The dosage depends on how much you want the color to be opaque on the canvas. It's better if we still see the pages on the background, so don't put too much color.

2. Paint the background

Apply the paint with a sponge up and down in different places of the canvas. The goal is to cutomize it slightly so don't put color everywhere but just in some places.

  • Duration of the step : 10 min
  • Let it dry for 1 hour

Step 4: The Drawing Grid

I present you with one of the methods that allow you to both work on a good basis and make progress : The grid method.

The grid method, which can also be called a proportion grid, is a method that allows you to draw from a photo or a picture and reproduce the proportions accurately while leaving very little room for error.

1. The grid on the reference picture

Take your reference picture, and define the frame on it. Once you have defined it, you can begin to draw a small line every 1.58 inches on the horizontal lines of your frame as well as on the vertical lines of your frame. Next, all you have to do is join with your ruler the marks previously drawn every 1.58 inches and thus make your grid.

2. The grid on the canvas

Next, we just have to draw the grid on the canvas.

The size of our canvas allows us to almost double the size of our reference picture, we will not draw 1.58 inches tiles on our canvas, but 3.27 tiles if we want to double the dimension. But it really depends on your canvas' sizes compared to the original picture's sizes.

Be careful :

Use a light pencil and if you do not have it, try not to force your line because it must be erased easily later.

Don't take too long to erase the grid. The more you wait, the harder it is to erase it as the paper may imbue the marks. So only let 2 days maximum.

  • Duration of the step : 40 min
  • Let it dry for 1 hour

Step 5: The Drawing

This step needs more attention than the others, but if you're careful, the grid's method should allow you to draw properly. To simplify your work don't hesitate to choose a reference picture less challenging and simple.

1. The primary lines

Have you ever played a "Battleship" game ? Well, it's more or less the same rules. Use a charcoal and an eraser to play !

To begin your draw, choose a point or a line on your reference picture and find in which tile of the canvas it should be drawn and where in that tile. Is it in the middle of the tile? The bottom? Top? Left? Right? In a corner?

This will help you be as accurate as possible.

If you want to be even more precise, you can also subdevide your tile into smaller ones.

2. The filling

Once the drawning's complete, you need to erase the grid and keep only your drawing.

Then we can start adding the shadows and all the details of the drawing.

Begin by the darker elements and use the acrylic painting to fill them. According to the size of the element don't hesitate to adapt your paintbrush.

Don't fill with paint the place you want to have your message to. We'll use a special type of paint for this.

For the shadows, use the charcoal and play with your fingers to shade forms.

Once complete you can spray your drawing with the fixative spray.

Be careful :

Only use your charcoal fixative spray until you are sure that your drawing's finished. Once sprayed, it's impossible to erase the charcoal.

  • Duration of the step : depends on your reference image, (3h for my drawing)
  • Let it dry for 1h

Step 6: Prepare and Place Your Message

We now have to glue the message that will appear under the thermochromic powder/paint.

Cut your message and glue it with the varnish glue.

You can also just draw or paint anything instead if you prefer.

Be careful :

Adapt your print to the part of the drawing you want to hide, the message must be totally recovered. For example on my paint i made the message so it doesn't overflows from the underwear.

  • Duration of the step : around 7 min
  • Let it dry for 1 hour

Step 7: Apply Termochromic Paint

Using the hermochromic powder is simple :

Take 1 teaspoon of black (or any color you want) thermochromic powder and 3 teaspoons of matte acrylic varnish on a cup and mix it until the substance becomes homogeneous. Apply it on your canvas as you would with a normal paint.

Don't hesitate to put multiple coats to get something as opaque as possible. But don't put too many coats either. Indeed, when heated, the paint doesn't actually becomes fully transparent. The more coats you apply, the less transparent it will be.

On my paint I put 2 coats.

  • Duration of the step : 2h 15min (with the drying between two applications)
  • Let it dry for 2 hours.

Step 8: Last Touches !

1. Projections

Mix black acrylic paint with water and project it on your canvas with a paintbrush in different places of your canvas.

2. Sign as an artist !

Don't forget to sign your work, be an artist ! Signing your art is part of the creative process.

3. Make it long lasting

After finishing your drawing, spray your canvas with the matte acrylic varnish.

Be careful :

Don't project too much painting on your canvas, keep it subtle.

  • Duration of the step : 5 min
  • Let it dry for 1 hour.

Step 9: Framing the Canvas

To value your work, take a photo frame bigger than your canvas.

Your photo frame is composed of :

- The bottom plate (1)

- A white paper (2)

- The glass (3)

- The frame(4)

1. Glue the white paper

With the varnish glue, stick the white paper on the bottom plate. You can use a ruler to remove the air between by sliding it from top to bottom. Take your time this step need to be carefully done.

Next, let it dry for about 10 minutes.

2. Glue your canvas

Stick your canvas in the center of the photo frame with the varnish glue. Make it so the gap on the left/right and top/bottom are as uniform as possible.

3. Paint the edge

Sticking the white paper is not easy. If you have air bubbles, or if you made any mistakes (paper dammaged with ruler or so) I have a solution for you ! Paint in white the part between canvas and the frame. Don't hesitate to put thick coats of paints to add texture.

Be careful :

  • Duration of the step : 40 minutes
  • Let it dry for 3 hours

Step 10: Enjoy !

Your canvas and your photoframe is dry ?

Time to hang it on your wall ! And try it !

Heat the paint with your hand, an hair dryer or the sun, an watch the magic happen !

You now have a handmade interactive painting !

Be careful :

The glass isn't a good thermal conductor so, if you want to use the heat of your hand to reveal the hidden message, it's better not to put the window above the paint.
But if you want the paint to dispear with the heat of the sun it will be ok to leave the window above the canvas.

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