Bubble glazing is a fun, simple way of decorating pottery.  To bubble glaze, you will need some bisque ware pottery, some underglaze, dishwashing liquid soap, and a straw.

Simply add a few tablespoons of water into a mug or glass.  Then add an equal amount of dishwashing soap to the water.  Choose the color of underglaze that you want the bubbles to be, then add a few tablespoons of underglaze to the glass as well. 

Find an old, shallow kitchen tray that you don’t need any longer, and put your bisque ware rim down in the tray.

Place your straw into the mixture in the glass and start to blow into the mixture.  The mixture will start to bubble up.  Allow the bubbles to spill out over the top of the glass and let them fall naturally onto the bisque ware in the tray. 

Move the glass of bubbles around as you blow, allowing the bubbles to cover the bisque.  Once covered, you can let the bubbles burst in their own time.  This will take a few minutes. 

When the bubbles have burst, they will leave behind a colored bubble effect impression in underglaze on the pot.

After the pot and underglaze have dried thoroughly, you can carefully apply a couple of layers of clear glaze before glaze firing your piece.    

Bubble Glazing Tip

One tip is that bright and darker colored underglaze works best with this technique.  Because the bubble pattern is quite delicate, muted or pale colors don’t stand out quite as well against the ceramic background.   

Reference -  thepotterywheel.com -