Experimenting and creating eschar effects

For my snake bite wound design, it has involved eschar on the wound and on below, I have tested out what method I should use to create a more realistic eschar effect and the rough texture of it. 

http://yxzl.baiduyy.com/chm11/jzyxtp/Ch.16_files/image032.jpg

With supracolor palette:
I have started off using the black color on the supracolor palette and use the back of the brush and stipple the color onto my hand.

 By using the supracolor palette, I think it doesn't work to create the eschar effect as the texture is not seen clearly and also I can't create the rough texture with it because it is very smooth and a bit shiny. 

After that, I started to think what I can use to create eschar texture and then I have come up an idea using ground coffee beans. After that, I have tried out this idea on my hand to see what it looks like.

With ground coffee beans:

https://cdn.shopify.com/s/files/1/0360/6353/collections/ground_coffee

 In order to stick the ground coffee beans onto the skin, I have used the multi gel and stick them onto the skin.

On below, it shows what the ground coffee beans looks like when putting on top of the multi gel on the skin. Although the ground coffee beans melts, but I like how you can still see the texture of it and I think it will works with the eschar effect. In order to create the black color for the eschar, I have tried to use the black color of the supracolor palette and applied on top of the ground coffee beans. I think the ground coffee beans work well with the eschar effect but in order to improve, I can apply more ground coffee beans onto the skin and lesser multi gel to let it dry quicker.