What makes Brood Comb such a dark colour???

[TapStoneBees]

Hello,
Had an observation hive today at a local festival....man was it HOT!!!!, And I'm not talking the festival or the attention the hive got, the weather was Crazy,

Had many people come up and look at the hive, they love the way the bees are encased in the glass....though we had a question I didn't know was correct in answering.  The group wanted to know, why is the brood comb dark, and the honey comb light.  What makes the brood comb so dark, age??  Or is it that there is a presence of both Pollen and maybe propalis in the wax comb to make it more nutritionally sound, and to give  better  strength and insulation??   

Didn't give an answer, but told the folk that I would be in touch with them for the answerr Of course that is where the all of you come in. 

Looking forwar to the reply.  I have checked my books, and there seemed to be no answer for that, and this is why I have reached out to the all of you.

Thanks again in advance.
Cheers,
JT

[Casimir]

It is caused by the cocoon around the brood and a pile of waste they produce.


Go down to page 78.
http://books.google.com/books?id=FMSN68-GjWoC&pg=PA78&lpg=PA78&dq=dark+comb&source=web&ots=R2fYz22-qx&sig=taMRJN6T1kAb0F7egFuOMpRjApk#PPA78,M1

[buzzbee]

Also, all the foot  traffic over the brood area helps to darken it.

[Bennettoid]

They need to learn to wipe their feet before entering the hive.

[Michael Bush]

Mostly cocoons.  Some of it is traffic.  But you never seen honey comb that never had brood in it turn black.  Layers of cocoons.  Every generation leaves one behind.