Subject: Why do candles weigh more after burning?

Our experiment was as follows:  5 different votives were weighed, they were 
placed in 5 different holders (all the same) and the holders were weigh.  
The holders weighed 3 oz each.  4 of the candles weighed 1 oz each and the 
5th candle weighed .75 oz.  The holders are glass and shaped like a flower 
pot so the candles were sitting down in the holder.  The top of the holder 
is completely open.  Each candle was burnt for 2 hours.  After the two hour 
time frame we let the candles cool down and then measured them in the 
containers.  (we figured we could subtract the weight of the container from 
 the total weight since we measured everything before burning the candles). 
 When we weighed the candles in the holders, they were now 1 oz heavier 
than the total weight of both the holder and candle before they were burnt. 
 What would cause them to have gained weight instead of losing it.  

Re: Why do candles weigh more after burning?