Soft plastic fishing lures are made primarily of plastisol, a mixture of polyvinyl chloride (PVC) resin suspended in liquid plasticizer, typically blended at a 50/50 ratio by weight. When heated and poured into molds, this combination transforms into the flexible, rubbery material that mimics worms, crawfish, shad, and dozens of other prey shapes. Beyond that base formula, manufacturers add salt, colorants, glitter, scent, and stabilizers to fine-tune how a lure looks, sinks, feels, and smells underwater.
The PVC and Plasticizer Base
At room temperature, plastisol is a thick, pourable liquid. It consists of microscopic PVC particles floating in a plasticizer, which is essentially an oily chemical that keeps the plastic soft and flexible once it cures. The type of plasticizer matters because it determines how stretchy, durable, and pliable the finished lure feels in the water. Most commercial soft plastics have historically used phthalate-based plasticizers. Two of the most common are diethylhexyl phthalate (DEHP) and dibutyl phthalate (DnBP), though both have drawn environmental scrutiny. Even lures marketed as “eco-friendly” have been found to contain PVC and phthalate plasticizers when independently tested.
The ratio of PVC to plasticizer shifts the lure’s firmness. A 50/50 split by weight is standard, but lure makers adjust this to create anything from a stiff jerkbait to an ultra-soft finesse worm. More plasticizer means a softer, more lifelike feel. Less plasticizer produces a tougher bait that holds up better on the hook but may not have the same natural wiggle.
How Plastisol Becomes a Solid Lure
Plastisol doesn’t cure through a chemical reaction like epoxy. Instead, it fuses through heat. When heated to roughly 325°F to 365°F, the liquid mixture melts into a fully flowable state that can be poured into aluminum or silicone molds. As it cools, the PVC particles and plasticizer lock together into a soft, rubber-like solid. This process is reversible: you can remelt old or damaged baits and pour them into new molds, which is one reason home lure-making has become so popular.
Heat stabilizers are added in small amounts to prevent the PVC from scorching or degrading during this heating process. Barium-zinc compounds are a common class of stabilizer used in plastisol processing. Without them, the plastic can discolor, release fumes, or become brittle.
Salt for Weight and Texture
Fine-grain salt is one of the most important additives in soft plastic lures. It serves three purposes: it increases the lure’s density so it sinks at the right speed, it gives the bait a grainy texture that feels more natural when a fish bites, and it provides a salty taste that may encourage fish to hold on a fraction of a second longer.
The amount of salt varies widely depending on the style of bait. A common starting point for home pourers is about two tablespoons of fine salt per four ounces of liquid plastic, but stick-style baits designed to be fished without a sinker use significantly more. A well-known formula for weightless stick baits calls for a 4:2:1 ratio: eight ounces of soft plastic, four ounces of fine salt, and one ounce of additional softener. That heavy salt load is what gives these baits their distinctive shimmy as they fall through the water column.
Color, Glitter, and Visual Attractants
Soft plastics get their color from liquid pigments or powdered colorants mixed directly into the plastisol before pouring. These can produce anything from translucent watermelon greens to solid blacks, and lure makers often layer multiple colors in a single pour to create two-tone or laminate patterns.
Glitter flakes add flash that mimics the reflective scales of baitfish. Most lure glitter is made from polyester film rather than metal. Polyester glitter is lighter than metallic alternatives, which helps it stay suspended throughout the body of the bait instead of sinking to the bottom of the mold during curing. It’s also microwave-safe, which matters for home lure makers who heat their plastisol in a microwave.
Scent Additives
Many soft plastics come impregnated with scent oils designed to mask the chemical smell of PVC or actively attract fish. Common scent ingredients include garlic juice, anise oil, and menhaden (a type of oily baitfish). Some formulations go further, incorporating minced crayfish or cricket material in trace amounts to produce a more natural prey odor. These scent compounds are typically suspended in a carrier like corn oil or beeswax, which helps them release slowly into the water over the course of a fishing session rather than dissipating all at once.
Thermoplastic Elastomer Alternatives
Not all soft lures are PVC-based. A growing number of baits use thermoplastic elastomers (TPEs), which are synthetic rubber compounds that offer a different set of properties. The most common TPEs in fishing lures are styrenic block copolymers, a family that includes materials like SBS (styrene butadiene styrene) and SEBS (styrene ethylene/butylene styrene).
TPE lures tend to be stretchier and more tear-resistant than standard plastisol baits. They spring back to their original shape more readily after being bitten or pulled through cover. The tradeoff is that they generally cost more and can’t be remelted at home as easily as PVC plastisol. They also accept salt and scent additives differently, so the feel and flavor profile of a TPE bait can be noticeably distinct from a traditional soft plastic.
Environmental Concerns
Soft plastic lures are one of the most commonly lost pieces of fishing tackle, and they don’t break down in water. PVC is not biodegradable, and the phthalate plasticizers it contains can leach into the surrounding environment. Research measuring the release of dibutyl phthalate from PVC microplastics in water found detectable concentrations within the first day, with levels persisting through 28 days of testing. Lost lures essentially become small pieces of plastic pollution on the bottom of lakes and rivers.
Efforts to create biodegradable soft baits have been ongoing, but progress has been slow. Independent analysis of lures marketed as environmentally friendly found that they still contained PVC and concerning phthalate plasticizers, suggesting that truly biodegradable alternatives have not yet reached the mainstream market in a meaningful way. For anglers concerned about their footprint, retrieving snagged baits when possible and reusing melted-down plastics remain the most practical steps.