Only use fresh clean wax - don't make the same mistake most make by using 'recycled' comb burr comb, scrapings from inspections etc - I've seen some awful grey and brown wax exhibits being entered before now, even at the 'National' Honey Show. Just use virgin cappings wax, even better if the honeycomb you got the cappings off is newly drawn stuff. Wash it well and pick out any dark or suspect bits, then dry it before melting down in a bain marie but remember never let it get to much more than about 70°C. First filter through a piece of double thichness stocking stretched over a bean tin with both ends removed and held in place with a rubber band, then further filterings should be done through a piece of surgical lint (fluffy side to the inside of the can)