pHpapir

pHpapir, or pH paper, refers to a range of disposable strips or rolls impregnated with pH-sensitive indicators. When dipped into an aqueous sample, the indicators undergo a color change that correlates with hydrogen ion concentration, allowing a quick estimate of how acidic or basic (alkaline) the solution is. The result is typically read by comparing the strip’s color to a reference color chart provided with the product.

There are two main types. Universal indicator paper contains a mixture of indicators that produces a color gradient from acidic to basic across the full pH range, usually shown as a 0–14 scale. Narrow-range indicator papers are calibrated for specific pH intervals (for example around neutrality or in the acidic range) and can offer more precise readings within that interval. Some kits include separate strips for different ranges or a combination pack.

To use pH paper, you dip a strip briefly into the sample, wick off excess liquid, and compare the color on the strip to the chart. Colors should be interpreted at a standard temperature, as temperature can shift the appearance. For turbid or strongly colored samples, the reading may be unreliable, and preparatory steps or dilutions may be necessary. Because color interpretation is qualitative, pH paper provides a quick estimate rather than a precise measurement; for exact pH values, a calibrated pH meter is preferred.

Storage should be in a sealed container, away from direct sunlight and moisture, and strips should be used before their expiration date. pH paper is widely used in education, chemistry, biology, environmental testing, food and beverage production, and hobby contexts such as aquariums and soil testing.