Rainbow Watercolor Resist Painting

The watercolor resist technique produces results that feel like magic — children draw with white crayon (which seems to make no mark at all), then wash watercolor over the top, and the hidden drawing appears. For St. Patrick's Day, drawing a white crayon rainbow that reveals itself under a wash of rainbow colors creates a moment of genuine wonder.

What You'll Need

• White crayons — Crayola works well; avoid generic brands which can be too translucent
• Watercolor paints — either pan watercolors or diluted liquid watercolors
• Watercolor paper or thick cardstock — thin paper buckles under the wash
• Paintbrushes — medium and wide, for applying watercolor washes
• Water and paper towels

How to Do It

Step 1: Draw with white crayon. On white paper using white crayon, draw a rainbow arc with heavy pressure — the key is pressing hard so enough wax transfers to the paper to resist the paint. Draw clouds at each end and a pot of gold beneath.

Step 2: Check the wax transfer. Hold the paper at an angle to the light — you should see a slightly shiny area where the crayon was applied. If not, press harder.

Step 3: Mix watercolor washes. Mix each rainbow color in a separate paint container with plenty of water for a transparent, bright wash.

Step 4: Paint the rainbow bands. Apply each color in a wide stripe following the arc of the hidden rainbow. As the paint meets the crayon wax, it beads up and pulls away, revealing the white lines underneath.

Step 5: Add background. While the rainbow dries, paint the sky blue above and green grass below. Let areas bleed together slightly for an impressionistic effect.

Step 6: Reveal and discuss. Ask children why the white shows through — introduce the concept of wax repelling water.

Skills Your Child Will Develop

Scientific thinking — Observing that wax repels water introduces material properties and cause-and-effect reasoning.

Color mixing — Watercolors bleed into each other at edges, creating unexpected combinations.

Fine motor pressure control — Pressing hard enough with the crayon requires sustained intentional pressure.

Tips & Variations

• Use white oil pastel instead of crayon for an even stronger resist effect.
• Draw a shamrock outline in white crayon for a simpler version.
• Extend the science: test which other materials resist water (oil, Vaseline, wax paper).

My Two Cents

The reveal moment — when the watercolor hits the wax and the hidden image appears — is genuinely thrilling for preschoolers. Build it up: "I wonder if anything is hiding on that paper." Then let them discover for themselves.