How To Tape Curved Lines For Painting a Rainbow

Step 1: Prep the Surface Before Painting

Before applying tape and paint, it’s important to prepare the entire surface, whether it’s natural wood or a painted surface. This means ensuring that the surface is both clean and dry.

In this post, I didn’t cover the process of painting the desk before applying the rainbow design. If you have any questions about that, including the best paint to paint a desk, please check out the video tutorial or leave a comment below.

Step 2: Measure Out the Curves

Step 3: How to Draw Curved Lines with a Pencil 

To create curved lines, the best thing to use is a pencil and a string.

First, tie the string around the pencil. Then, select a fixed starting point, like a nail or the corner of a desk. Place the pencil at the point you have already measured and keep it vertical.

Lastly, pull the string taut and draw the curve of the line. By using this method, it avoids needing a steady hand to draw the lines precisely.

Step 4: Best Masking Tape for Curved Lines

The best tape for curved lines is precision masking tape or modelling tape. Tamiya tape and Modelcraft both do good flexible tapes.

This type of tape is stretchy, allowing you to wrap it around the curve of the rainbow for more precise lines. Also as it is low tack, you can remove and readjust it until you are satisfied with the shape you have created.

To achieve a crisp edge with your painting, smooth out the tape as much as possible to remove any air bubbles.

To apply the tape, attach it to the outer edges of the coloured lines you’re painting. Not on top of the lines. This will ensure that the lines remain visible.

After the tape is in place, use an eraser to remove any pencil marks if they are too dark. As they will still be visible under lighter colours of paint. Make sure to do this before applying the coat of sealer.

Step 5: Seal the Edges of the Masking Tape

When painting curved lines, using flexible fine line tape and sealing the tape is equally important.

Applying a thin coat of sealer to the edge of the tape creates a barrier that prevents the paint from seeping under it.

This base coat is the key to achieving a nice sharp line when painting.

Allow the sealer to dry before moving on to the painting coat.

Step 6: Paint the First Set of Curves

When painting multiple stripes alongside each other, like in a rainbow, it’s important to paint them in two stages. Begin by painting the outer edge colour and then each alternate stripe.

Make sure to finish painting these stripes with as many coats of paint as needed before moving on to the in-between stripes. All the paints used here needed two coats, except for the yellow which required four.

This fine line masking tape is flexible, and it comes in different widths ranging from 2mm to 10mm. The piece of tape here is 3mm wide.

It’s essential to be careful while using narrower tape as you have to ensure that you don’t paint over the edges. If you’re using narrower tape, you can double-tape the curved line to give yourself more margin for error.

But if you accidentally paint beyond the outer edge of the tape, try to remove the paint with a wet wipe quickly. If left to dry, you can paint over it with the colour that it should be.

Step 7: Remove the Masking Tape

When you remove the tape, the paint should be dry to the touch which usually takes about an hour.

You don’t want to wait too long between each step. Taping, sealing, painting, and repeating with the other colours, takes a while to make progress.

Step 8: Tape and Seal the Second Set of Curved Lines

To paint the in-between curves, follow the same process as the first set. Ensure that the paint is completely dry as the tape will be applied on top of the painted curves.

Apply the tape so that a small edge of the painted colour is visible.

Then, seal each line of tape before painting the next set of colours.

Step 9: Paint the Inner Stripes of the Rainbow

Then finally, repeat the painting process with the inner stripes of the rainbow.

The only paint colour that required mixing was indigo.

To create it, you can combine the purple and blue paints to achieve a natural midpoint colour. Make sure to mix enough paint to account for multiple coats. As it may be challenging to match the exact colour if you don’t make enough the first time.

Does Flexible Masking Tape Work for Straight Lines?

Finally, I continued the rainbow pattern down the sides of the desk to give it more dimension.

You could use Frog Tape to mask the straight lines. However, this flexible masking tape still works well for a straight edge.

This type of tape is perfect for getting clean lines on both curved and straight edges.

Desk Makeover with Painted Curved Lines

Painting curves with tape is a straightforward process. It requires a few simple steps and a bit of patience to let each layer dry.

Each part doesn’t take a long time to do. But it does take time over many hours.

This technique can be used to get clean paint lines on both furniture and walls.

The extra straight lines on the edges of the desk create an interesting dimension that enhances the painted rainbow effect.

If you don’t feel confident in creating curved lines by hand, this is a great way to achieve professional-looking results.

Using these bright colours, you can transform plain furniture into fun and vibrant pieces.