NOVELTY - Producing a precursor solution, comprises creating a mixture comprising water, resorcinol compound, and a catalyst, heating the mixture to 30-99 degrees C to create a heated component mixture and adding a cross-linking agent to mixture by a programmed-addition method comprising: dividing the cross-linking agent into batches; mixing batches of cross-linking agent to the heated component mixture to form a solution; cooling the solution to 30-99 degrees C; optionally repeating mixing and cooling steps; maintaining the final solution at 45-55 degrees C for 15-480 minutes; and cooling to less than 40 degrees C.    USE - The method is useful for producing a precursor solution, which is useful for producing sol-gel used for making nano-engineered carbon material (carbon aerogel or carbon xerogel) (all claimed), where the precursor solution is also useful to make carbon filter paper, and the nano-engineered carbon material is useful in supercapacitor applications, high-surface-area electrodes, high-voltage electrode, fuel cells, desalination systems, composite materials, reinforcing agents, pigments, insulators, in media for gas separation or storage, controlled-release agent carriers, electro-chemical storage devices, catalysts, architectural daylighting, oil and gas pipelines, coatings formulations, foams, papers, industrial and cryogenic plants and vessels, outdoor gear and apparel and personal care products.    ADVANTAGE - The method: provides safe manufacturing of precursor solutions on a large scale (e.g. 10000 lbs), by controlling the release of chemical energy, thus lowering the risk of container rupture or explosion; and provides nano-engineered carbon material substantially free of impurities.    DETAILED DESCRIPTION - Producing a precursor solution comprises creating at least one component mixture comprising water, at least one resorcinol compound, and at least one catalyst, heating the component mixture to 30- 99 degrees C to create a heated component mixture and adding at least one cross-linking agent to the heated component mixture by a programmed-addition method comprising: dividing the cross-linking agent into batches; mixing one of many batches of cross-linking agent to the heated component mixture; cooling the solution to 30-99 degrees C; optionally repeating mixing and cooling steps as necessary to consume all of the remaining batches of the cross-linking agent to create a final solution; and where each batch comprises the cross-linking agent sufficient to prevent the maximum temperature increase resulting from the reaction occurring in the mixing step from exceeding 10 degrees C per minute; maintaining the temperature of the final solution at 45-55 degrees C for 15-480 minutes; and cooling the final solution to less than 40 degrees C. INDEPENDENT CLAIMS are also included for:    (1) making a sol-gel, comprising preparing the precursor solution and subjecting the precursor solution to at least one heat treatment at 60-99 degrees C for 12-96 hours; and    (2) making a nano-engineered carbon material, comprising preparing the sol-gel and subjecting the sol-gel to at least additional treatment.