Subject: Do wax candles burn at different rates because of dyes?

I'm doing a science fair project about which candles burn the fastest, 
and it seems that white candles and colored candles burn at different 
rates.  Does the dye in a candle affect the burning rate?

Also, does the shape of a candle affect the rate of burning, or is it 
just the total amount of wax in the candle?

I'm also assuming that candles made of different materials (for 
example, wax and beeswax) would burn differently. 

Re: Do wax candles burn at different rates because of dyes?