Blotches

Blotches are irregular patches of color or shading on a surface. They can occur on living tissue, textiles, paper, or natural materials, and may range from subtle to conspicuous. A blotch is typically larger than a spot and lacks a uniform border.

In dermatology, blotches describe patches of discolored skin. They may be flat and vary in color from light brown to dark red. Common types include age spots, birthmarks, vitiligo patches, and pigmentary or vascular conditions. Some blotches are benign, but new or changing patches should be evaluated by a clinician, especially if they alter in size, shape, or color.

In printing, painting, and photography, blotching refers to uneven ink or pigment distribution that creates irregular patches. Causes include paper absorbency, moisture, changes in ink viscosity, or drying conditions. Remedies involve adjusting materials, improving drying, or using blotting techniques to even out the surface.

In biology and ecology, blotches are natural color patterns that can help with camouflage or warning. Animals may display blotched fur or skin, while plants can have blotched leaves due to disease or nutrient deficiency.

On built environments or artifacts, blotches can arise from moisture intrusion, mold growth, or chemical reactions that alter surface color. Proper cleaning, sealing, or replacement may be required.

This term is generally descriptive rather than diagnostic; specific meanings depend on context.