Electroforming Question: Why is my piece dull and not plating?

Electroforming is easy, yet there is a lot to learn.  One of the most FAQs we get is: Why is the copper plating surface not bright and shiny? What am I doing wrong? This happens after plating a few pieces. It's frustrating because it's hard to understand why this suddenly happens when previous pieces plated just fine. The good news is that you can polish it to a high shine because it is simply rough copper. But make sure you formed the copper thick enough before sanding or polishing. Here is a pdf to explain why copper can look dull and how the acids are depleted from the plating solution, even after electroforming just a few pieces. The easiest answer is to buy new plating solution.  However, read this to understand the reasons why:  Maintaining your copper plating solution

Edited to add:
We also have a new video about how to shine up your piece with a brass brush and polishing pads!