Saflex Evoca RSL

In a horizontal architectural laminating line, Saflex Evoca RSL is handled as a rolled polyvinyl butyral sheet supplied in nominal thicknesses of 0.38 mm, 0.76 mm, and 1.52 mm; the roll is cut to size in a clean room maintained at 18–25 °C and 20–50% RH. Before layup, the sheet moisture content is verified against the lot certificate and adjusted toward a target of 0.4–0.6% because lower moisture reduces PVB-to-glass adhesion and higher moisture drives edge bubble formation during autoclave heating. Typical facade safety-glazing build-ups pair 6 mm annealed or heat-strengthened glass with a 0.76 mm interlayer, yielding a nominal overall thickness of 12.76 mm; interior borrowed lights may use 3 mm / 0.38 mm / 3 mm, while structural or large-format panels move to 8 mm / 1.52 mm / 8 mm or 10 mm / 1.52 mm / 10 mm to improve post-fracture retention. The assembled stack is de-aired through either a nip-roller pre-lamination station or a vacuum bag; the autoclave cycle is then held at 12–14 bar and 130–140 °C for a load-dependent dwell of 90–180 min, after which the load is cooled to below 50 °C before release. Compliance for this segment is demonstrated against EN ISO 12543-2:2022 for laminated glass, ANSI Z97.1 for safety glazing used in buildings, and ASTM C1172 for the laminate specification. The terminal products include curtain-wall vision glass, storefront laminates, elevator enclosures, and interior partitions. Process limitations are material-specific: float glass tin-side orientation must be controlled because PVB adhesion to tin-side surfaces can shift when sheet moisture content is near the lower end of the process window, and edge contamination from cutting oils or hand oils must be excluded before layup. When the RSL grade is supplied under a mass-balance or recycled-content allocation scheme, the assigned recycled feedstock percentage appears only on the chain-of-custody document and is not an input to machine settings; the mechanical and rheological controls follow the same PVB lamination window established for the relevant sheet thickness.

What Is the Minimum Interlayer Thickness for EN 12600 Overhead Retention?

The retained-fragment requirement in overhead and sloped glazing is not met by glass type alone; the interlayer must maintain a continuous adhesion plane after cracking so that glass fragments remain adhered to the sheet. Saflex Evoca RSL is typically specified at 1.52 mm for overhead units, often as a single 1.52 mm ply or as two 0.76 mm plies, combined with 6–10 mm heat-strengthened or fully tempered glass. A representative build-up is 6 mm heat-strengthened glass / 1.52 mm Saflex Evoca RSL / 6 mm heat-strengthened glass, with the heat-strengthened route preferred where large glass fragments are required for residual load transfer. The lamination process for sloped units requires a longer de-airing stage than vertical facade panels because curved or oversized canopies trap air at the edge; vacuum-bag de-airing is generally used instead of nip-roller pre-lamination, and the autoclave dwell may be extended to 150–180 min at 12–14 bar and 130–140 °C to complete flow into the glass surface. The relevant performance tests are EN 12600 for impact performance classification, ASTM E2353 for dynamic impact on overhead glass, and EN 14449 where the laminate is supplied as a safety-glass component. The terminal products are skylights, sloped facades, canopies, and atrium glazing. A specific processing boundary is roller-wave depth on heat-strengthened glass: excessive roll wave prevents complete de-airing and produces edge bubbles; the glass supplier’s flatness data should therefore be checked against the de-airing equipment’s capability before the interlayer is cut.

Balustrade and Point-Fixed Facade Interlayer Mechanics

Because post-breakage load transfer in a point-fixed facade panel is controlled by interlayer adhesion, hole-edge geometry, and the shear modulus of the interlayer at in-service temperatures, Saflex Evoca RSL requires a project-specific design check rather than a direct substitution for structural ionoplast grades where the design relies on high post-breakage shear stiffness. In balustrades and point-fixed facades, the typical build-up is 8 mm / 1.52 mm / 8 mm or 10 mm / 1.52 mm / 10 mm heat-strengthened glass, with the interlayer installed as one 1.52 mm ply or two 0.76 mm plies to reduce optical distortion around the holes. Holes are drilled and finished before heat strengthening and lamination; after autoclave, the interlayer is recessed around each hole to permit clamping hardware and to prevent the bolt from compressing the PVB directly. This interlayer cut-back is typically specified as a 2–5 mm clearance around the hole circumference, but the exact value is project-dependent and should be confirmed by the hardware supplier. The lamination process uses vacuum-bag de-airing followed by an autoclave cycle at 12–14 bar and 135–140 °C; point-fixed panels require controlled cooling because uneven cooling introduces edge stress that can later cause local delamination at the hole perimeter. The structural design is checked against DIN 18008 or EN 16612 for glass strength, while ASTM E1300 may be used for load resistance in North America; the laminate itself remains within EN ISO 12543-2:2022. Terminal products include glass balustrade infill panels, glass fins, point-fixed canopies, and stair enclosures. The main process conflict is the low shear modulus of PVB above 40–50 °C: for facades with high permanent load at the point fitting, the design engineer must either reduce the point-fitting spacing or specify a structural interlayer; published data for this specific configuration is limited and should be validated by a full-size panel test.

Frequently, forced-entry-resistant glazing is assembled from multiple glass plies and two or more Saflex Evoca RSL interlayers to extend the post-fracture load path under repeated impact. A representative multi-ply build-up for a forced-entry rating is 8 mm annealed glass / 1.52 mm Saflex Evoca RSL / 8 mm annealed glass / 1.52 mm Saflex Evoca RSL / 8 mm annealed glass, though project-specific thicknesses are determined by the required resistance class. The de-airing and autoclave cycle for multi-ply stacks is more severe than for single-interlayer panels: trapped air between adjacent PVB plies is removed by vacuum-bag de-airing, and the autoclave dwell must be extended to 180–240 min at 12–14 bar and 130–140 °C to ensure creep of the interlayer into the glass surface. Edge stagger between successive interlayer plies is maintained at 5–10 mm to avoid a straight-line moisture path and to improve long-term edge stability. Compliance is demonstrated through EN 356 for resistance classes, UL 972 for burglary-resistant glazing, and ASTM F1233 for security glazing test methodology. Terminal products include bank teller glazing, convenience-store security partitions, safe-room windows, and embassy barrier glazing. The process limitation is multi-ply glass alignment: even small offsets between plies create a visible step at the edge and can reduce the effective clamped area; batch-to-batch variance in interlayer thickness should be monitored with a calibrated micrometer before layup because cumulative thickness differences across several plies can shift the autoclave press load distribution.

When Traffic-Noise Glazing Combines a Low-E Coating with the Laminated Pane

When a magnetron-sputtered low-emissivity coating is used in the same glazing unit as a Saflex Evoca RSL laminated pane, the coating stack must be edge-deleted and positioned on a glass surface that does not contact the PVB interlayer. The laminated build-up is usually asymmetric for traffic-noise control: 6 mm outer glass / 0.76 mm or 1.52 mm Saflex Evoca RSL / 4 mm inner glass, with the low-E coating placed on the cavity-facing surface of the outer or inner pane in the insulating-glass unit, not on the PVB contact face. The asymmetric thickness shifts the coincidence dip and can improve the sound reduction index; however, the damping contribution of a single PVB interlayer is limited, and acoustic targets often require thicker PVB, multi-ply interlayers, or a dedicated acoustic PVB grade. The lamination process for coated panes requires the coating edge deletion width to match the edge bite, typically 10–15 mm, and the de-airing route must avoid dragging the interlayer across the coated surface before alignment. The autoclave cycle remains at 12–14 bar and 130–140 °C for 90–150 min. Acoustic performance is measured per ISO 10140-2 or ASTM E90; published data for this specific configuration is limited, so project specifications should require a full assembly test rather than a glass-only estimate. Terminal products include railway-station glazing, highway-facing hotel windows, and airport terminal partitions.

For museum and archival laminated panels, the PVB interlayer functions as an ultraviolet attenuator in the 300–380 nm band, reducing UV transmittance to levels suitable for light-sensitive exhibits when a 0.76 mm sheet is used. A common build-up is 3 mm low-iron glass / 0.76 mm Saflex Evoca RSL / 3 mm low-iron glass; low-iron glass is selected to compensate for the slight green-gray tint of the PVB sheet and to maintain high visible transmission. The process for archival panels is a clean-room lamination sequence without a nip roller; vacuum-bag de-airing is preferred for smaller display-case sizes, followed by autoclave at 12–14 bar and 130–140 °C for 90–120 min. Because the interlayer is hygroscopic, the cut edges of an exposed display-case laminate must be sealed or protected from high-humidity environments; prolonged exposure above 60% RH can cause edge clouding and delamination. Optical and UV performance is evaluated under EN 410 or ISO 9050; safety performance is covered by EN ISO 12543-2:2022. Terminal products are display cases, picture glazing, museum partitions, and archival framing. The operational boundary is the plasticized PVB’s low abrasion resistance: the laminate should not be used as a direct wear surface, and cleaning agents containing ketones or strongly alkaline formulations must be excluded from the written maintenance procedure.

Interior Partition Lamination Requires Neutral-Cure Edge Sealing

Interior partition laminates are often produced on smaller vacuum-bag lines rather than high-speed nip-roller lines, and the edge sealant selection determines long-term edge durability of Saflex Evoca RSL. The typical stack for an office partition or glass door is 4 mm / 0.38 mm or 4 mm / 0.76 mm / 4 mm depending on acoustic and safety requirements; 0.38 mm is used for lightweight partitions, while 0.76 mm is specified for doors and movable walls. The lamination cycle uses vacuum-bag de-airing at room temperature followed by autoclave heating at 12–14 bar and 130–140 °C for 90–120 min; after cooling to below 50 °C, the laminate is edge-trimmed and inspected for bubbles or delamination. The edge sealant must be a neutral-cure silicone; acid-curing or acetate-curing silicones release acetic acid during cure, which attacks the PVB edge and can produce local delamination or hazing. Compliance for interior safety glass is demonstrated under EN ISO 12543-2:2022 and ANSI Z97.1; for fire-rated partitions, the laminated panel is usually only a component in a larger system and must be tested as part of the complete framing assembly. Terminal products include office partitions, glass doors, movable walls, and conference-room enclosures. A processing boundary for this segment is the small format: multiple small panels loaded in a single autoclave basket can mask uneven pressure distribution, so basket loading plans should place larger panels at the top and maintain separation between stacked units to prevent surface marking from contacting PVB edges.