Green glass float

I have been working on sketches of a glass floats.  Glass floats are perfect for studying the reflection and refraction of light.  Handmade glass floats were used in many parts of the world by Fishermen to keep their nets, longlines or droplines afloat.  Most floats made in Japan are green because the glass was recycled from sake bottles.  Small air bubbles are often trapped in the float's glass by the rapid heating and cooling of the process.  The blown floats are sealed with a 'button' of melted glass.  Some glassblowers added their mark, usually near the sealing button.

The float was lit by a single strong light source to provide intense highlights and dark shadows.  There are additional reflections and refractions around the glass float.  The challenge was to capture both the solid shape of the object as well as its transparency.  The sketch to the left was done as an exercise, and used as the bases for the final painting.

First I painted the green and yellow washes for the background and foreground.  Then added the light transparent green for all but the area on the glass float that is highlighted.  Additional green glazes were added to darken parts of the float where the glass is thicker or there are shadows.

More glazes of green were added to darken the bottom of the glass float, and yellow highlights were added.  The rope around the near side of the glass float were added, as well as the rope shadows.  Highlights and shadows were added to the rope to shape the twisted  strands.

Lighter impressions of the rope behind the glass float and cast shadows from the rope on the glass float were added.  Additional shadows were added through out the painting.  The use of multiple values is important in creating the three dimensional illusion.  They enhance the round shape of the float as well as explain the translucent and transparent aspects of the glass float.