Bubble bubble: a background technique

It's hard to create art when many of your art supplies are packed away and stored at another location. So today I'll share a simple background that many of you may have tried, but always fun, fun, fun to make.
Supplies from left:
shallow bowl of water
Dawn dish washing liquid (this brand seems to produce the best effects)
food coloring
straw
substrate of your choice

Add about twenty drops of color and a small amount of soap to the water

Without stirring your mix, begin blowing through the straw. Be careful not to inhale into, or suck on, the straw.

Continue blowing until you have a mound of bubbles well above the lip of your bowl.

Using very little pressure, quickly press the substrate into the mound of bubbles, being careful to avoid the lip of the bowl. Have your substrate nearby and work quickly, because the bubbles have a tendency to pop if you allow them to sit too long. Blow more bubbles, then repeat. Always blow bubbles each time. For a different effect, allow you substrate to dry and add more than one color to the page.

There are three colors in this completed piece.