a b s t r a c t Systematic deformation of a moving precipitation front into a 2D stationary profile by a pH field gener-ated by acidic and basic reservoirs and its design procedure are discussed. Results indicate that in some pattern formation systems, where the pattern emerges by a precipitation reaction of metal and hydroxide ions, phenomena can be governed by a complex pH field. The pattern formation can be described and dis-cussed by taking into account acid–base chemistry. Our approach, which relies on solving either time-dependent reaction–diffusion equations or derived Laplace's equation, provides a reasonable description of the system.