So you have set up your Copelandia kit correctly and after a week or so a white layer starts forming on top of the substrate, is this a problem?
The short answer is no. If you would be growing a Cubensis mushroom this would be a reason for concern, but not for the Copelandia. This is part of the normal process. First, they will make a big layer of fluff, as seen in the picture below, and after this you will see little pins start popping out in the next week.
When you see the little pins coming out you should make sure that no water gets onto the mycelium anymore. The Copelandia really doesn’t like water, so if you have water droplets lying on top, like in the picture below, the little pins might abort (see here for more info) prematurely or become black.
When this happens, spray some water in the bag every 2 days. When you do this, take the kit out of the bag and place it on a well-sterilized surface. Then squeeze the bag so all the old air will be pushed out and fill it again with fresh air. Spray some water once on both sides of the inside of the bag and place the kit back in the bag. Close it up and put it back on your grow spot. For more info about how to set up your kit properly please see here
If you see that the drops are forming again on the substrate or the mycelium you know you are spraying too much.
pic1. White Copelandia mycelium growing on top of the substrate