Saint-Gobain CHR 2995-11R is a glass-foil backing silicone adhesive pressure-sensitive tape supplied in roll form for high-temperature masking, surface protection, and thermal-spray shielding. The backing is a composite of woven glass cloth and aluminum foil, giving the product a reflective, cut-resistant face combined with the dimensional stability of glass reinforcement. Manufacturer-published typical values include a total thickness of 0.18 mm (7.0 mil), a continuous service temperature range from -73°C to 260°C, a peel adhesion to stainless steel of approximately 13.7 N/25 mm (50 oz/in) when tested in accordance with ASTM D3330, and a tensile strength at break of approximately 657 N/25 mm (150 lbf/in) when tested in accordance with ASTM D3759. The silicone adhesive is selected for high-temperature stability and clean removal from metals after thermal exposure, although removal characteristics are substrate-dependent and require process validation.

The aluminum foil face is electrically conductive. The tape is therefore not intended for primary dielectric isolation in high-voltage circuits unless the design explicitly accounts for the conductive foil layer and the potential for short-circuit paths at cut edges. In electrical applications, the product is more commonly used as an abrasion-resistant reflective facing or heat-shielding wrap rather than as a replacement for insulating polyimide or polyester films.

How Does the Glass-Foil Backing Modify Peel Force and Thermal Transfer Relative to Polyimide Masking Tapes?

The glass-foil backing of CHR 2995-11R distinguishes it from polyimide/silicone masking tapes in conformability, thermal reflectance, and resistance to grit-blast erosion. Polyimide/silicone tapes typically have a total thickness of 0.06–0.08 mm and an elongation at break above 50%, which permits wrapping around complex contours and maintaining contact on small-radius features. The glass-foil laminate has a lower elongation at break of approximately 5%, meaning it is less conformable around tight radii but substantially more resistant to cut-through and scoring under angular alumina or silicon carbide grit. The foil face reflects a larger fraction of incident radiant load than polyimide film, reducing heat transfer into some masked regions, while the glass cloth layer contributes tensile strength and limits the tearing that can occur in unsupported foil tapes. Peel force after thermal exposure is controlled by the silicone adhesive rather than by the backing, but the laminate construction can influence removal by resisting stretch and by allowing a controlled near-180° peel without tensile deformation of the tape.

On plasma spray lines, the tape is applied over dovetail roots, cooling holes, threads, and adjacent zones prior to alumina or yttria-stabilized zirconia deposition. Substrate preparation normally consists of wiping the surface with a low-residue solvent such as isopropanol or a ketone-based cleaner and allowing full evaporation. The tape is burnished with a hand roller or squeegee to minimize air entrapment at the tape edge. Overlapping of tape edges by at least 3 mm is a common process practice to reduce grit intrusion, though the required overlap depends on blast angle, blast pressure, and gun-to-part distance. Masking failures in plasma spray operations are most frequently observed at tape termini that face the gun path, where the adhesive edge is exposed to rebound grit. This failure mode is mitigated by orienting splices away from the line of sight and by inspecting edges after each cycle.

Plasma Spray Masking and the Requirement for Post-Cure Clean Peel

The silicone adhesive system is chosen for its ability to withstand short-duration thermal loads during masking operations. After exposure at elevated temperatures, the adhesive builds adhesion to metal substrates, particularly stainless steels, titanium alloys, and nickel-based superalloys. Removal force increases with temperature and dwell time. When the tape has been exposed at 200°C for 60 min, removal is typically performed at a near-180° peel angle and a controlled peel rate below 300 mm/min to reduce adhesive splitting and foil-to-cloth delamination. These removal parameters are process-sensitive: high peel rates can produce adhesive transfer to the substrate, while very low peel rates may leave degraded backing material at the edge. Quantitative peel-build curves for CHR 2995-11R after extended thermal dwell are not fully published in public literature; removal parameters should therefore be established by trial on the actual substrate and with the actual thermal profile.

Silicone pressure-sensitive adhesives are known to migrate at elevated temperatures and can contaminate surfaces that will later receive wet paint, adhesive bonding, or plasma-enhanced chemical vapor deposition. Areas masked with CHR 2995-11R should be treated as silicone-contaminated until verified clean. Post-removal cleaning may require solvent wiping, plasma treatment, or mechanical abrasion depending on the downstream process. The tape is not recommended for masking components that are sensitive to silicone residues and cannot be cleaned after masking removal.

When Autoclave Curing Demands a Silicone Adhesive That Does Not Carbonize Below 260°C

Autoclave cure cycles for epoxy and bismaleimide composite parts often reach 180°C to 230°C. General-purpose acrylic or rubber-based tapes lose adhesion, soften, or leave carbonaceous residue before these temperatures are reached. CHR 2995-11R is appropriate where a silicone adhesive is required to survive the cure temperature without adhesive breakdown, and where the glass-foil backing provides a barrier to resin bleed and reduces mark-off on tooled surfaces. The tape is applied to composite bagging films, tool plates, or caul plates as a flash breaker or protective edge mask. Because the foil face is nonporous, it can limit resin penetration into the tape edge, although resin flow under pressure may still intrude where the tape is not firmly burnished against the tool surface.

The operational boundary for this product is defined by the silicone adhesive rather than by the glass or foil components. Continuous use above 260°C is not supported by manufacturer-published data. Short excursions above 260°C may be possible in non-loaded conditions, but published data for repeated excursions in this specific configuration are limited. The tape should not be used as a fire barrier or as a substitute for ceramic or metallic shielding when process temperatures exceed the continuous rating by more than 30°C for periods longer than several minutes.

For aircraft interior masking applications, burn compliance may need to be demonstrated under FAR 25.855(a). The user should request test data from Saint-Gobain for the specific product and lot because flammability performance can be affected by adhesive thickness, backing lamination, and contamination. REACH and RoHS status should be verified through Saint-Gobain’s product compliance documentation for the specific lot, since raw-material changes can affect declarations.

Adhesion Build, Shelf Life, and Storage Conditions

Silicone pressure-sensitive adhesives typically exhibit time-dependent adhesion build. Initial adhesion after application is lower than adhesion measured after a 24 h dwell at 23°C and 50% relative humidity. This behavior is relevant when the tape is applied and then immediately exposed to grit blasting or high-temperature cure. Where maximum adhesion is required, the tape should be dwelled for at least 24 h at controlled room temperature before thermal exposure, provided the substrate is clean and dry. Adhesion build is slower on low-energy surfaces such as PTFE, acetal, and some powder-coated surfaces, and the tape may not achieve the published peel values on those substrates.

Storage of CHR 2995-11R should follow standard pressure-sensitive tape handling practices: rolls should be kept in their original packaging at 21°C and 50% relative humidity, protected from ultraviolet light, and not stored near strong oxidizing agents or solvent vapors. Material life is commonly stated by manufacturers as 12 months from date of manufacture when stored under these conditions, but the user should confirm shelf-life requirements against the current Saint-Gobain technical bulletin because product revisions can alter storage classifications. Rolls should be allowed to reach room temperature before application in cold environments because condensation on the adhesive can reduce initial tack and lead to edge lift during subsequent heating.

The tape is not a direct substitute for polyester/silicone masking tapes in low-temperature, low-abrasion operations because the glass-foil backing is stiffer and carries a higher material cost. It is also not a direct substitute for PTFE-glass tapes where a low-friction release surface or chemical barrier is the dominant requirement. Selection between CHR 2995-11R and alternative high-temperature tapes should be based on the specific balance of thermal load, grit erosion, conformability, electrical conductivity, and post-removal surface cleanliness defined by the manufacturing specification.