Tiegrsi
Songster
Have you tried addressing the feather issue through nutrition? I did a quick search and saw several different nutrition and environmental based recommendations. "Silkie feathers" on an Ayam Cemani would look something like this.
I have not, but they eat the same food as my other birds, (20%starter/grower + grit and occasional mealworms), and NONE of my other breeds have this issue. They have had feather issues since I got them (one of them had NO feathers on his back and they took a while to grow in. They weren't plucked out, they were simply not there, like they hadn't formed.) I will get some good pics later tonight to show you.
Is there a particular food or food item or nutrient that is good for making strong feathers besides protein and calcium? (They do not currently get supplemental calcium - I only give that to my layers.)
You can kind of see it here, where at the end it looks like the feather has frayed and the barbules have separated and the feather looks more choppy instead of smooth along the shaft. The point where it goes from smooth to choppy is where the feathers are breaking off on them. It's like a weak point 