The Rishonim maintain, and thus is it ruled in the Mishne Berura, that ink used for sta"m be produced from certain materials, as sofrim have been doing all through history according to an unchallenged tradition.
A new ink recently introduced is derived from the smoke of petroleum combusted together with gas and a small measure of olive oil, plus artificial ingredients which produce an end product of a thick, black silicon-like liquid. The ink is very durable but non-traditional.
The rabbonim of the Eida Hachareidis held a special consultation together with a talmid chochom expert from Bnei Brak. They examined the ink and as a result formulated a sharp letter forbidding the use of this new product, after HaRav Moshe Shaul Klein had already banned its use. Without going into painful details about the marketing of this ink by the dealers (in the hope that they will regret their unseemly behavior and repent), we must nonetheless clarify that one must be very careful in the future in purchasing ink.
In a talk with one of the veteran ink producers we learned that the main ingredients of the special ink used by the scribe are gall nuts, or the gallic acid derived from these nuts; gum arabic, a resin; and copper vitriol (kupper vasser), a bluish stone which gives the ink blackness. Generally speaking, the gall nuts are cooked in water for about an hour. A bit of rubber resin is added to improve the absorption of the ink on the parchment. Then the vitriol is added and the mixture is boiled until half remains. The exact details are a trade secret.
