Thermafoam has a medium weight. It is made of a polyester and cotton blend; 70 percent of the material is polyester and 30 percent is cotton. The material also has a slight feel of rubber in its texture.
While thermafoam itself is medium weight, this lining is designed for use with all weights of fabric, from light to heavy. It offers some limited sun protection. It does this by diffusing light shining against it, but it cannot completely black out the sun's rays.
Blackout lining is another available option. It is also made of a polyester and cotton blend. It contains the same percentages of each material as thermafoam, but blackout lining is a heavyweight drapery lining option.
Blackout lining is made to work with both medium or heavyweight drapes. It completely blocks out the sun's fading rays. It is not specifically made for lighter-weight drapes, but can accomplish complete blackout of the sun if an additional lining is used. This additional material is an interlining used to increase the thickness of the blackout lining.