In thermal power plants, deposition of fly ash on the surfaces of the heat exchanger causes a significant drop in the heat-transfer efficiency and this inhibits effective fuel utilization. It is widely accepted that alkali metals such as sodium and potassium are the trigger for fly ash deposition given that the alkali metals potentially form low-melting-point materials which have adhesive properties and can be deposited on the surface of the exchanger. However, detailed mechanistic studies of this process are challenging due to the chemical complexity and diversity of fly ash samples collected from commercial thermal plants. Herein, it is demonstrated that fly ash deposition triggered by alkali metals can have different mechanisms due to the effects of interparticle and/or surface adhesions. A key enabler for facilitating detailed mechanistic studies is the combined use of tensile and shear strength testers linked to a synthetic ash strategy that utilizes chemically synthesized inorganic particles.