Dammit!

[Project355]

In a pinch pulverized black charcoal will sub as carbon introductory media, AKA Kasenit, which was bone charcoal. Gotta grind it REAL fine tho, like dust.

 

[SGW Gunsmith]

Amazon has a similar product to Kasenit:

https://www.amazon.com/s?k=kasenit&ref=nb_sb_noss

Bottom of the page that comes up.