Polymers - Forensics 2026

PET/PETE (Polyethylene Terephthalate)

1

HDPE (High Density Polyethylene)

2

PS (Polystyrene)

6

LDPE (Low-Density Polyethylene)

4

PP (Polypropylene)

5

PVC (Polyvinyl Chloride)

3

PMMA (Polymethyl Methacrylate)

7 (Other)

PC (Polycarbonate)

7 (Other)

Cotton

Burns easily with an active flame, and the fabric tends to burn quickly. Yellow-orange flame. Light gray smoke. Burns with a natural, plant-like smell (similar to burning paper or wood).

Wool

Tends to burn slowly and self-extinguishes when the flame is removed. It can also smolder for a while. Yellow-orange flame with some flickering. Burns with a characteristic smell of burning hair or feathers (because of the keratin protein).

Silk

Burns easily but at a slower rate compared to cotton. It also tends to shrink back from the flame. Yellow-orange flame. Little smoke.

Linen

Burns readily but tends to burn more slowly than cotton. Yellow-orange with some flickering. Light-gray smoke. Burns with a smell similar to burning paper.

Nylon

It is a synthetic fiber and burns slowly when exposed to a flame. It tends to melt before it fully burns. Yellow-orange with a slight blue edge. Black smoke, especially as it melts.

Spandex

Highly flammable and burns rapidly. It will melt and shrink away from the flame, leaving a melted residue. Blue flame with some yellow-orange at the tip. Black smoke.

Polyester

Synthetic polymer and melts when exposed to flame, rather than burning quickly. Blue with a yellow-orange tip. Black smoke as the material melts and drips.

Medulla

The innermost layer of the hair shaft. It is a soft, spongy, and often hollow core that can vary in thickness depending on the individual and their hair type.

Cortex

The thick, middle layer of the hair shaft, and it makes up the majority of the hair's structure. It's located between the medulla and the outer cuticle.

Cuticle

The outermost layer of the hair shaft, consisting of overlapping scales of keratinized cells.

Root

The part of the hair that is embedded in the skin and is responsible for hair growth. It is located within the hair follicle, a tiny sac in the skin.

Hair scales

The overlapping cuticle cells that make up the outermost layer of the hair shaft.

Coronal scales

Resemble stacked crowns or cup-like structures. Small rodents, bats, and some other mammals.

Imbricate scales

Flattened, overlapping scales similar to roof shingles. Humans and many mammals, including dogs and cats.

Spinous scales

Petal-shapes scales that protrude outward. Seals and other mammals.