CA glue (cyanoacrylate, commonly sold as super glue) fails to bond with several common materials, most notably polyethylene, polypropylene, silicone, and PTFE (Teflon). These materials all share one trait: extremely low surface energy, which prevents the glue from wetting the surface and forming a chemical grip. Beyond those outright failures, CA glue also bonds poorly to greasy or oily surfaces, certain rubbers, and glass over time.
Polyethylene and Polypropylene
These two plastics are the most well-known CA glue failures, and they’re everywhere: plastic bags, food containers, bottle caps, cutting boards, storage bins, and many automotive parts. Researchers working with cyanoacrylate actually use polyethylene and polypropylene containers specifically because the glue won’t stick to them during experiments.
The reason comes down to surface energy. For any adhesive to bond, it needs to spread across and “wet” the surface. Plastics with surface energy below about 40 dynes per centimeter resist this wetting. Polyethylene sits around 31 and polypropylene around 29, well below that threshold. The glue essentially beads up rather than spreading into a thin film, so it never makes meaningful contact with the material.
Specialty primers exist that can overcome this limitation. These primers, typically based on ammonium carboxylate compounds, chemically modify the plastic surface so CA glue can grab onto it. In lab testing, the best primers created bonds strong enough that the plastic itself broke before the glue joint failed. However, the primers need to be applied shortly before gluing. Some lose effectiveness after prolonged air exposure because they react with carbon dioxide in the atmosphere or absorb into the plastic surface.
Silicone
Silicone is another notoriously difficult material for CA glue. Its surface energy is very low compared to metals, glass, and most other plastics, which means standard cyanoacrylate forms weak, easily peeled bonds at best. This applies to silicone rubber, silicone sealant, silicone molds, and silicone-coated surfaces.
Researchers have found two approaches that improve results. The first is modifying the CA glue formula itself with additives like silane coupling agents and wetting agents, which roughly doubled bond strength in testing. The second, more effective approach is pretreating the silicone surface with a primer (isopropanol mixed with a small amount of a basic compound). Surface pretreatment pushed bond strength from negligible to around 6 MPa, a roughly threefold improvement over formula modification alone. For most home and workshop users, though, the practical takeaway is simpler: if you need to bond silicone, use a silicone-specific adhesive rather than CA glue.
PTFE, Wax, and Other Low-Energy Surfaces
PTFE (sold as Teflon) has one of the lowest surface energies of any solid material, around 18 dynes per centimeter. CA glue will not bond to it under normal conditions. The same applies to wax, parchment paper, and most release agents used in mold-making. These materials are actually useful as non-stick surfaces when working with super glue, since drips and spills peel right off.
Powder-coated metals can also resist CA glue, not because the metal underneath is incompatible, but because the coating itself may have low surface energy or a texture that limits contact area.
Greasy, Oily, or Contaminated Surfaces
CA glue cures when it contacts moisture on a surface. Even a thin film of water vapor is enough to trigger rapid polymerization. But when a surface is coated in oil, grease, or other contaminants, those substances form a barrier that prevents the glue from reaching the surface itself. The bond forms with the contaminant layer rather than the material, so it peels away easily.
This is why fingerprints on glass or metal can weaken a joint. Skin oils create a microscopic barrier. Cleaning surfaces with isopropyl alcohol or acetone before gluing dramatically improves results on materials that CA glue should otherwise bond to well.
Glass: Bonds but Doesn’t Last
CA glue does stick to glass initially, sometimes quite strongly. But glass is one of the worst choices for a long-term CA bond, for two reasons.
First, the thermal expansion mismatch is enormous. Glass expands at roughly 5 millionths per degree, while cured cyanoacrylate expands at 70 to 80 millionths per degree. That’s a 15-fold difference. Every temperature swing puts stress on the bond line as the glue expands and contracts far more than the glass does. Over enough heating and cooling cycles, the joint cracks.
Second, cured CA glue is vulnerable to moisture, and glass surfaces attract and hold water molecules. Over time, water diffuses into the bond line and breaks down the polymer chains through hydrolysis. This degradation accelerates in alkaline conditions (pH above 7), which is why glass items washed with soap lose their CA bonds faster. For permanent glass repairs, UV-curing optical adhesives or two-part epoxies are far more reliable.
Cotton, Wool, and Cellulose Fabrics
This is less a case of “won’t stick” and more a case of “don’t try.” CA glue reacts dangerously with cotton, wool, and other cellulose-rich fibers. These fabrics are packed with hydroxyl groups, which massively accelerate the curing reaction. The polymerization happens so fast and across such a large fiber surface area that it generates serious heat.
In testing, the reaction between cyanoacrylate and cotton fabric reached average temperatures of 68°C (154°F), with some products hitting 75°C (167°F). That’s hot enough to cause full-thickness burns on skin underneath the fabric. Medical literature documents cases of children and adults burned when super glue (including nail adhesive, which is the same chemistry) contacted cotton clothing against skin. The glue doesn’t fail to bond here. It bonds too aggressively, and the heat generated in the process is the real problem.
Heat and Moisture Limits
Even on compatible materials, CA glue has environmental boundaries that effectively make it “not stick” under certain conditions. Standard ethyl cyanoacrylate bonds begin to fail at around 82°C (180°F). Methyl cyanoacrylate holds slightly higher, to about 90°C (195°F). Specialty high-temperature formulas extend this to 200°C (392°F), and the most heat-resistant allyl cyanoacrylate grades can reach 250°C (482°F), but those are industrial products, not the super glue from the hardware store.
Prolonged water exposure also degrades bonds over time. The ester bonds in cured cyanoacrylate are inherently susceptible to hydrolysis. Submerged or frequently wet joints will weaken and eventually fail, particularly in soapy or alkaline water. For any joint that will see sustained heat or moisture, epoxy or polyurethane adhesives are better choices.