BLOCK HARMFUL LIGHT RAYS. Light rays can damage your artwork. Take care to protect watercolor paintings from ultraviolet (UV) rays. These rays are powerful enough to cause damage to organic materials, resulting in loss of color, yellowing and/or darkening. They can cause the paper to become brittle. UV-filtered glass or acrylic will block out most (but not all) harmful rays. "post your opinion in the comments" Or, send me an email Thank You: Join Our Email List Email: BLOCK HARMFUL LIGHT RAYS. Light rays can damage your artwork. Take care to protect watercolor paintings from ultraviolet (UV) rays. These rays are powerful enough to cause damage to organic materials, resulting in loss of color, yellowing and/or darkening. They can cause the paper to become brittle. UV-filtered glass or acrylic will block out most (but not all) harmful rays. "post your opinion in the comments" Or, send me an email Thank Yo