Bubbles and tearing almost always come down to three things: plastic that is too hot or too cold, moisture or trapped air, and plastic that is too soft for the bait. Get your plastisol to over 350°F on the initial heat, stir gently, keep everything dry, and match durometer to the bait, and most problems disappear.
Here is a quick troubleshooting guide to the most common soft plastic problems and how to fix each one.
Bubbles in your baits
- Stirring too aggressively whips in air. Stir slow and smooth.
- Pouring too fast traps air in the cavity. Pour in a steady stream.
- Plastic too cold is thick and holds bubbles. Get it fully to temp and fluid.
- Moisture in the cup or mold is cold and forms condensation. Keep everything bone dry.
Baits tearing off the hook
- Plastic too soft. Add hardener or step up to a firmer durometer.
- Too much salt or softener. Both reduce durability, so dial them back.
- Under-cooked plastic never fully converted. Make sure you reach over 350°F on the initial heat.
Incomplete fills or short shots
- Plastic cooling before it fills. Keep it hot, and warm open pour molds on a griddle.
- Injecting too slowly. Fill with steady, even pressure.
- Cool injector. Keep the injector warm so plastic flows freely.
Scorched, yellow, or smoking plastic
- Overheating. Heat in short bursts and stir. Between them; do not blow past 350°F.
- Too many reheats. Add heat stabilizer to reheat more times without discoloring.
Cloudy or dull finish
- Plastic not hot enough looks cloudy. Bring it fully to temp.
- Dirty or oily mold. Keep milled aluminum molds clean for that glossy, store-bought finish. Use Dawn dish soap and warm water. Avoid harsh detergents and chemicals.
A quick pre-pour checklist
- Everything dry.
- Thermometer handy, target about 350°F.
- Stir slow, pour steady.
- Durometer matched to the bait.
- Mold warm (open pour) and clean.
Frequently asked questions
Why are my soft plastic baits full of bubbles?
Usually air from stirring or pouring too fast, plastic that is too cool, or moisture. Stir gently, pour steadily, reach temp, and keep everything dry.
Why do my homemade baits tear so easily?
The plastic is too soft or under-cooked, or you added too much salt or softener. Use a firmer durometer or add hardener, and fully convert the plastic at about 350°F.
Why won't my mold fill completely?
The plastic is cooling before it fills. Keep it hot, warm open pour molds, and inject with steady pressure.
Why is my plastic turning yellow?
Overheating or too many reheats. Heat in short bursts, stir, and add heat stabilizer.
Pour cleaner baits
A quality injector that holds heat helps prevent bubbles and short fills. Dialing in the basics fixes most issues fast. Browse molds by category to expand your setup.
By the Angling A.i. team