File:Chromatography.pdf Essentially, a circular filter paper (Whatman #1) with a cylindrical paper wick sitting in a 0.5% solution of silver nitrate is allowed to absorb the solution, which spreads by capillary action, to a certain diameter. The wick is removed and the paper is dried. Meanwhile, the substance to be tested is mixed with a 0.1 to 1% solution of sodium hydroxide and let stand for a period of time. The prepared filter paper is then allowed to absorb this solution and the substance spreads over the paper. When it has spread to a certain distance, the wick is removed and the paper dried. The paper is then exposed to indirect sunlight to let the image develop.