303 Mold & Mildew Cleaner & Blocker - 16oz

The 303 Mold & Mildew Cleaner & Blocker – 16oz is purpose-built for boat owners, anglers, and marine equipment enthusiasts who understand that mold and mildew are relentless threats in saltwater and freshwater environments. After years on the water, any boater knows that moisture, shade, and warm conditions create the perfect breeding ground for fungi that compromise gel coat, upholstery, canvas tops, and engine compartments. This specialized formula tackles existing growth while creating a protective barrier that inhibits new spore formation—essential maintenance for protecting your investment and preserving resale value.

This cleaner works through a dual-action mechanism: active ingredients penetrate and dissolve mold colonies on contact, while a secondary treatment layer blocks moisture and UV exposure that fungi need to thrive. The 16oz format is sized for targeted application on deck hardware, cabin interiors, vinyl seating, fiberglass surfaces, and storage lockers where mold commonly takes hold. Its concentrated formula means you get multiple applications per bottle, reducing the frequency of reordering during peak boating season when humidity and confined spaces accelerate fungal growth.

Serious boat owners—whether you're running a center console offshore, maintaining a sailboat, or storing a cabin cruiser—benefit most from preventative use before seasonal layup and as part of routine spring commissioning. The blocker component delivers ongoing protection between applications, making it ideal for high-moisture zones like engine bilges, head compartments, and covered areas with poor ventilation. Compatible with all standard marine materials including fiberglass, vinyl, canvas, and wood trim, this product integrates seamlessly into any maintenance regimen and delivers the kind of reliable performance that keeps your vessel—and your time on the water—free from mold-related headaches.