Enhancing the potentially monochromatic

One of the creative "problems" in composing for a group like a flute quartet is the ensemble itself.  With minor exception this is a homogenous ensemble.  The sound quality and color is very similar from top to bottom.  I am used to composing for ensembles with contrasting colors.  I like to have a veritable palette of colors inherent in the ensemble to draw from.  It is not to say that an ensemble such as a flute quartet is monochromatic.  There is a color palette there, I just need to be creative and draw it out.  I believe that this is the first time I have come across this issue since I composed my trombone quartet in 1999.

I know that this is a good challenge for me.  One of my primary interests as a composer is using tone color and drawing upon diverse sounds.  My challenge is to get creative and really figure out what the flute can do.  What techniques are there that really make this instrument special?  I don't think that trying to compose a flute quartet without digging in and exploring techniques and performance styles would allow me to create the piece that I want.

I also need to remind myself of basic elements that can add another layer of color and interest to the music: articulations.  As a composer there are times when this element becomes an afterthought and I include them in the score to add interest.  I think I should challenge myself to focus on some articulations and compose parts of this piece with that as a primary feature.