Calcium for your finches

Calcium is very important to finches especially if they are breeding.  Just like humans moms need calcium.  However they all need it for strong bones and beaks, but especially for egg production.  If a hen does not have enough calcium to produce a hard shell, it could rupture inside the bird when she is trying to lay it and this can cause death.  Or if she lays the egg and the shell is not hard, it will crack when she sits on the egg to incubate it.  So it is very important. 
It can come in several ways.  One of my favorites is crushed oyster shell.  Not powder but tiny pieces.  Just think how small their throat is and it must be swallowed to get into the crop.  This also helps with the grinding of the food they eat in the crop. 
Second way is Cuddle Bone.  This should be available like the oyster shell at all times.  They will eat the cuddle bone and also use it to groom their beak.  Very important.  If you can find the softer ones at bird shows rather than the "Manufactured" ones at the pet shops, they are better.  Bigger, cheaper and softer.
Third great way to recycle is when you use eggs for yourself, wash out the shells, and store them in an airtight bag in the freezer.  When you have enough, crush them up, put them on a piece of parchment paper, and put them in the oven at 325 degrees for about an hour.  Once they are very brittle, poor them into a bag and use a rolling pin or crusher to break them up to very tiny bits and give them to your birds in a separate dish like the oyster shell. 
Very important and easy to give.