Polyurethane Film: The Complete Guide to Wazoodle's PU Film Material

What Polyurethane Film Is and Why It Matters

Polyurethane Film is a raw 100% polyurethane membrane — the waterproof barrier material that gets laminated to fabric to create PUL (Polyurethane Laminate). Unlike pre-laminated PUL fabrics that come ready-to-sew with the film already bonded to a knit backing, this is the standalone film itself. Available in 3 mil (60 GSM) or 4 mil (80 GSM) thickness at 60–62" width, it provides complete waterproof barrier with breathable vapor transmission.

The appeal is customization and thinness. By working with the raw film, makers choose their own fabric substrate and control exactly how thin the finished product is. Customers report finished items made with PU Film are substantially thinner than those made with pre-laminated PUL — a meaningful advantage in cloth diapers, menstrual pads, and other products where bulk directly affects comfort. The film exhibits 30% bidirectional stretch with full recovery, maintains soft hand feel through hundreds of wash cycles, and blocks 100% liquid penetration.

The tradeoff is difficulty. This is an experienced-sewer material. The film is exceptionally slippery, sticks to sewing machine components, and requires specialized handling techniques that multiple customers describe as "extremely difficult" when starting out. Made in USA by AKAS Tex, CPSIA certified for children's products, Forever Chemicals-Free (no PFAS, BPA, phthalates).

This material requires experienced sewing skills. Multiple customers emphasize that sewing experience is necessary before attempting projects with PU Film. The film slips, stretches, and slides during handling — working with it takes significantly more time than pre-laminated PUL. If you're new to waterproof sewing, start with pre-laminated PUL and graduate to raw film after building confidence with slippery materials.

Working With Polyurethane Film: Essential Techniques

The handling challenges are real — but solvable with the right techniques. Every tip below comes from customer-validated experience.

The Sandwich Rule

Always sandwich the film between fabric layers before sewing. This is the single most important technique. Placing the film between two layers of fabric (such as flannel) dramatically improves workability — prevents slipping, stretching, and sliding. Treat the sandwich like regular PUL fabric.
Pin only at corners and within seam allowances: Every pin hole compromises waterproof integrity. Use binder clips instead of pins wherever possible outside seam allowances.

Machine Setup

Walking foot is nearly mandatory: Sewing without a walking foot is described as "next to impossible" due to the film's slipperiness when layered with fabric. With a walking foot, the process becomes manageable.
Parchment paper prevents sticking: Place parchment paper or notebook paper between the film and the presser foot. The paper prevents the film from adhering to machine components and tears off easily without damaging stitches.
Universal needles over ballpoint: Counterintuitively, universal needles combined with post-sewing heat sealing produce better results than trying to minimize holes with ballpoint needles.

Cutting and Marking

Indelible markers only: Washable pens, pencils, and fabric markers smear on the polyurethane surface. Use permanent markers for pattern tracing.
Cut slightly inside traced lines: The film tends to stretch during handling — cutting just inside the pattern line compensates for this tendency.
Sandwich for cutting too: Securing the film between fabric layers improves cutting accuracy by eliminating slippage.

Sealing Needle Holes

Steam iron on medium-high seals needle holes: After sewing, run a steam iron on medium-high setting over stitch lines. This melts the polyurethane slightly around each needle hole, resealing the waterproof barrier. This technique with universal needles proved more effective than trying to prevent holes with specialty needles.

Common Applications for Polyurethane Film

Cloth Diaper Construction (AI2, AIO, Hybrid) — The primary use case. PU Film creates the waterproof barrier in All-in-Two, All-in-One, and hybrid diaper styles where the film is protected between fabric layers. Finished diapers are noticeably thinner than those made with pre-laminated PUL while maintaining equivalent waterproof performance.
Reusable Menstrual Pads — Waterproof backing layer creating slimmer pad profiles than PUL alternatives. The thinness advantage is particularly valued in menstrual products where bulk affects wearability and discretion.
Bag Linings — Customer-validated for creating waterproof bag interiors where the film provides leak protection for contents. The 30% stretch accommodates bag flexing during use.
Mattress Protectors — Breathable waterproof barrier for bed protection. Vapor transmission prevents heat buildup while liquid blocking provides complete mattress protection.
Custom PUL Creation — Makers laminate the raw film to their chosen fabric substrate using heat bonding, creating custom PUL with specific fabric aesthetics and hand feel.

NOT recommended for pocket diapers. Pocket-style construction requires repeated insertion and removal of absorbent inserts through an opening — the film is too vulnerable to tearing from this handling, plus contact with rings, jewelry, or sharp objects during insert changes. Use pre-laminated PUL for pocket diapers.

Polyurethane Film Care and Specifications

Wash at medium temperature. Dry at medium heat — avoid high heat which can damage the polyurethane. The film maintains soft hand feel and waterproof performance through hundreds of wash cycles. A characteristic "crinkly" sound is normal in finished products and diminishes during use. Avoid fabric softeners which can compromise the waterproof barrier.

Storage note: Customer reports suggest the film can deteriorate during long-term storage. Use within a reasonable timeframe after purchase — material stored for several years may become unusable.

Specification	W-450 PU Film
Material	100% polyurethane membrane
Available Thicknesses	3 mil (60 GSM) or 4 mil (80 GSM)
Width	60–62"
Stretch	30% (both directions, full recovery)
Waterproof	Yes — 100% liquid blocking
Breathable	Yes — vapor transmission
CPSIA Certified	Yes
Forever Chemicals-Free	Yes (PFAS, BPA, phthalates, lead)
Made in USA	Yes

All specifications may vary ±10% due to textile industry manufacturing standards.