PVB vs EVA vs SGP: Choosing the Right Laminated Glass Interlayer

Laminated glass gets its strength from the interlayer sandwiched between the panes, not just the glass itself. PVB, EVA, and SGP are the three interlayers most fabricators choose between, and each one calls for a different autoclave cycle. Picking the wrong film for the application, or running it on the wrong cycle, is the difference between a laminate that holds together after impact and one that delaminates at the edges within a year. This guide breaks down what each interlayer does well, where it falls short, and how its processing temperature lines up with what a glass laminating autoclave needs to run it correctly.

PVB gives up edge durability for optical clarity and sound damping

Polyvinyl butyral is the interlayer most laminators reach for first. It produces some of the clearest laminates on the market and dampens sound better than most alternatives, which is why it shows up in automotive windshields and acoustic architectural glass. PVB also absorbs impact energy well, holding shattered glass in place instead of letting it scatter.

The tradeoff is moisture. PVB is hygroscopic, meaning it draws in humidity from the air, and exposed edges that aren’t sealed properly can haze or delaminate over time in humid or outdoor settings. Layup has to happen in a controlled, low-humidity environment, and the film needs careful handling before it goes into the autoclave.

EVA cross-links during the cycle, trading some clarity for moisture resistance

Ethylene-vinyl acetate cures differently than PVB. Instead of simply melting and re-solidifying, EVA cross-links chemically during the autoclave cycle, which is what gives the finished laminate its resistance to moisture. That makes EVA a common choice for solar panel encapsulation and for decorative glass, since the film also takes silk-screening and patterned rolling well.

EVA’s weak point is UV exposure. Left in direct sunlight for years, it can yellow or discolor, which rules it out for architectural applications where the laminate needs to stay clear long term. It processes at a lower temperature than PVB, which shortens the heat-up portion of the cycle, but the cross-linking reaction still needs to run to completion before the glass comes out.

SGP trades a narrower process window for roughly five times the strength of PVB

Ionoplast interlayers like SGP sit in a different category mechanically. At the same thickness, SGP is roughly five times stronger and about a hundred times stiffer than PVB, so a laminate keeps its structural integrity even after the glass itself has cracked. That stiffness is why SGP shows up in structural glazing, hurricane-rated assemblies, and other applications where the interlayer has to keep carrying load after a break.

SGP is also more moisture-sensitive before lamination than PVB or EVA, so pre-press assembly needs a low-humidity cleanroom and a vacuum step to pull trapped air from between the layers. Its processing window is narrower too: the autoclave has to hold temperature and pressure more precisely than a PVB or EVA cycle requires.

Processing temperatures and typical applications side by side

Matching the interlayer to the autoclave’s cycle

Each of these interlayers needs a different heat-up rate, soak time, and cooling profile, and running the wrong cycle is as much a risk as picking the wrong film. PVB and EVA both tolerate a wider temperature band, but SGP’s narrower window means the chamber has to hold temperature uniformity tightly and follow a controlled, gradual cooling ramp to avoid thermal stress in the laminate.

Because the three interlayers don’t share a cycle, the equipment matters as much as the film. If you’re specifying or replacing a glass lamination system, tell us which interlayer you’re running and we can help scope it around that cycle; request a glass autoclave quote to start that conversation.