Copper electroforming solution is made with a blue crystal called copper sulfate, among other ingredients such as sulfuric acid and brightener if you use the Midas Bright from Rio Grande. As you use your solution the other ingredients start to dry up when you don't replenish your solution with distilled water.
Often times you don't notice these blue crystals until you go to filter your solution. Then, you notice at the bottom of your jar, tub, etc. a bunch of large blue crystals, or sometimes you'll see them attached to your anode.
So, what to do with these copper sulfate crystals? Aren't they still good to use? How can I reintroduce them to the rest of my solution?
Simply leave the copper sulfate crystals in your jar while you filter the rest of the solution, often times they sick to the bottom making it easy to filter everything without having to remove the crystals.
Then pour in just a little but of distilled water, swish around your jar if you can, if you're using a larger bath you may just want to let it sit. Add more distilled water as needed until the crystals are re-hydrated and you can add it to the rest of your solution.
Prevent your solution from drying out by periodically adding distilled water to your bath. It's hard to give an exact amount. I use a 16oz mason jar as my bath and I'll add 2-3 tablespoons, by eye, to my bath when I see my bath has evaporated a little. You'll have to get to know your bath and how much you need depending on the size.
If you have any questions pleas leave them below and I'll get to them!