An adhesive that shrinks as it cures builds stress into the joint before the product ever ships. That stress shows up later as bond-line gaps, warped parts, cracked optics, and premature delamination. Controlling shrinkage is a matter of material choice, process discipline, and joint design. Why Adhesives Shrink Curing is polymerization. Small monomer molecules join into a large cross-linked network, and as they bond they pack more tightly than they did as a liquid. The result is a volume reduction, typically expressed as percent linear or percent volumetric shrinkage. The figure varies by chemistry: Filled epoxies: roughly 0.5 to 2 percent volumetric. Unfilled epoxies: 2 to 4 percent. Acrylics and methacrylates: 3 to 8 percent. Cyanoacrylates: 5 to 10 percent. Low-shrink UV formulations: engineered below 2 percent, some below 1 percent. A second contribution is thermal. If the adhesive cures hot and then cools, it contracts further, and any mismatch with the substrate adds stress. See how CTE mismatch causes adhesive bond failure. Material Selection Choose a filled or low-shrink grade Inert fillers such as silica, alumina, or glass microspheres occupy volume without reacting. Raising filler content from near zero to 50 percent by weight can cut volumetric shrinkage by half or more, while also lowering CTE and raising modulus. Prefer controlled cure chemistries Two-part epoxies react through addition polymerization with no byproduct and relatively low exotherm, so they shrink less and more predictably than fast single-part systems. Use low-shrink UV grades for precision work When dimensional accuracy or optical clarity is critical, purpose-built low-shrink UV adhesives hold tolerances that other chemistries cannot. Pair them with a controlled light source; see choosing a UV lamp for resin curing and UV glue versus epoxy for transparent bonding. Process Control Cure slower and cooler A fast, hot cure drives the reaction quickly and concentrates the volume change into a short window, locking in stress. Curing at the lowest recommended temperature for the longest acceptable time lets the network relax as it forms. Meter accurately and avoid over-application Every excess milligram of adhesive is extra material that will shrink. Dispense a controlled, repeatable bead and design the joint so squeeze-out is minimal. Fixture through the cure Holding the parts in a fixture until the adhesive reaches gel and then handling strength prevents shrinkage forces from pulling the assembly out of position. Consider a staged cure For thick bond lines or potting, cure first at a low temperature to reach gel, then step up to complete cross-linking. The gel stage absorbs much of the volume change before the material is rigid enough to transmit stress. For UV adhesives, a two-step exposure, a low-intensity tack cure followed by a full-dose final cure, achieves the same stress relief. Joint and Part Design Keep the bond line thin Total shrinkage scales with adhesive volume. A 0.1 mm bond line shrinks far less in absolute terms than a 1 mm one. Design consistent, minimal gaps. Shape fillets to use less adhesive A concave fillet uses less material than…

A bonded joint is a system, and the adhesive is only its most visible part. The largest single cause of adhesive bond failure in manufacturing is not the adhesive; it is a surface that was never properly prepared. Getting that step right is what separates a bond that lasts from one that peels. The Science of Adhesion Adhesion works through two mechanisms acting together. Mechanical adhesion comes from the adhesive flowing into microscopic pits and grooves on the surface and locking in place once cured. A rougher, cleaner profile gives more of this interlock. Chemical adhesion comes from molecular attraction, including hydrogen bonds and covalent bonds, between the adhesive and the substrate's outermost molecular layer. Both mechanisms need the adhesive in intimate contact with the true substrate. A film of oil a few molecules thick, a fingerprint, a weak oxide layer, or mold release agent breaks that contact and caps the achievable strength at a fraction of its potential. See how CTE mismatch causes adhesive bond failure for a related failure path that surface prep alone cannot fix. Step One: Clean Cleaning removes organic and inorganic contamination before it can be sealed under the adhesive. Grease and oil: wipe with isopropyl alcohol, acetone, or a dedicated degreaser using a two-cloth method. The first pass lifts the bulk contaminant, the second removes the residue the first left behind. Wiping with a single saturated cloth just spreads the oil. Dust and particulate: remove with filtered compressed air or a tack cloth immediately before bonding. Mold release: injection-molded plastics carry silicone or wax release agents that resist solvent alone. These need a dedicated release-agent remover or an abrasion step. Let solvents flash off completely. Bonding onto a wet surface traps solvent in the bond line. Step Two: Abrade For smooth metals and hard plastics, abrasion increases surface area and strips weak boundary layers such as loose oxide and oxidized polymer skin. Mechanical abrasion: hand or machine sanding with 120 to 320 grit, grit blasting with alumina, or a non-woven abrasive pad. Aim for a uniform matte finish with no bright spots. Always clean again afterward to remove abrasion debris. Chemical etching: acid or conversion-coating processes used in controlled production to prepare aluminum, titanium, and some low surface energy plastics. These give the most repeatable results but require handling and disposal controls. Step Three: Activate Low surface energy plastics such as polypropylene and polyethylene, with surface energy near 29 to 31 mN/m, will not hold a durable bond without raising that energy. Plasma and corona treatment: an electrical discharge oxidizes the surface, adding polar groups and raising surface energy above 40 mN/m. The effect is repeatable and line-compatible but decays over hours to days, so bond soon after. Flame treatment: a fast, low-cost oxidation method for large polyolefin parts. Primers and adhesion promoters: a thin coating that chemically bridges the substrate and the adhesive. This is often the most practical route for low-volume work. For plastic assembly, the Uni-Weld plastic bonder grade guide covers…

Dielectric grease and conductive grease look similar in the tube and do opposite jobs in a circuit. One insulates and protects a connection from the environment; the other creates or improves an electrical path. Choosing the wrong one can cause intermittent contact, corrosion, or a dead short. Dielectric Grease: The Insulator Despite the name, dielectric grease does not conduct electricity. "Dielectric" means it strongly resists current flow. It is typically a non-hardening silicone compound used to seal, protect, and lubricate electrical connections rather than to carry current. Its functions are: Sealing out moisture, salt, dust, and corrosive gases at spark-plug boots, battery terminals, trailer connectors, and multi-pin housings, preventing corrosion and tracking. Lubricating rubber and plastic so connectors mate and separate without tearing seals or galling pins. Suppressing surface arcing and flashover in high-voltage boots and terminals by covering the creepage path. A key point that confuses many users: applying dielectric grease to a connector does not block the connection. When two contacts are pressed together, the metal-to-metal force displaces the grease at the contact points, and current flows normally while the grease continues to seal the surrounding area. The grease should coat the housing, seals, and unmated surfaces, not be relied on to be "pushed through" on a marginal contact. Conductive Grease: The Electrical Path Conductive grease is formulated to establish and maintain a low-resistance electrical connection. It carries a filler of conductive particles, such as carbon, graphite, silver, or copper, suspended in a grease base. Its purposes are: Improving continuity by filling microscopic surface roughness and air gaps between mating parts, lowering contact resistance. Preventing the oxidation and corrosion that raise resistance and cause hot spots over time, especially on aluminum conductors. Bleeding off static charge in assemblies with moving or rotating parts. Typical uses include grounding straps, busbar joints, aluminum-to-copper transitions, switchgear contacts, and battery cable lugs, where a stable, low-resistance joint is essential and where a bolted connection alone may loosen or oxidize. Choosing Between Them Ask what the grease is doing at that specific interface. If the connection is a positive mechanical contact, such as a plug and socket or a crimped lug, and the goal is to keep water and corrosion out, use dielectric grease. If the connection relies on broad surface area to pass current, such as a bolted busbar or a ground plane, and the risk is rising resistance from oxidation, use conductive grease, applied per the manufacturer's guidance to avoid bridging adjacent terminals. Never use conductive grease inside a multi-pin connector with closely spaced contacts, where it can bridge pins and create shorts. Never rely on dielectric grease to fix a high-resistance bolted joint; that needs mechanical correction and, where specified, a conductive compound. Email Us with your connector or joint type and environment for guidance on the right compound. Application Best Practices For dielectric grease, apply a light film to the connector housing, the seal or boot, and the exposed metal around the contact, not a thick fill that traps…

Plumber's putty has sealed sink drains and faucet bases for decades. That track record leads some technicians to reach for it on industrial equipment. For most industrial gasket applications the answer is straightforward: it should not be used, and the reasons matter. What Plumber's Putty Is Plumber's putty is a soft, malleable, oil-based compound made for watertight seals around non-pressurized plumbing fixtures. Its defining traits are: Non-hardening: It stays pliable, so fixtures can be adjusted or removed easily. No cure time: Assemblies can be used immediately. Easy to handle: It molds and applies by hand. Those properties suit low-pressure household tasks where easy removal is the priority. They become liabilities in an industrial joint. Why It Falls Short as an Industrial Gasket No adhesive strength: Plumber's putty is a sealant, not an adhesive. It does not bond to surfaces and adds no structural strength, so it shifts under vibration, pressure, and thermal cycling. Limited temperature and pressure range: It can harden, crack, or flow at elevated temperature and turns brittle in the cold. It offers almost no resistance to internal or external pressure, ruling out pressurized lines, hydraulics, and vacuum service. Chemical incompatibility: Being oil-based, it can soften or dissolve on contact with solvents, process fluids, and some lubricants. Material attack: The oils in some formulations degrade plastics such as ABS and PVC and can stain or embrittle porous materials over time. Poor with dynamic loads: A non-hardening, non-adhesive putty cannot hold a seal under the movement and vibration of running machinery. Differential thermal movement alone is enough to break the seal, for the reasons set out in this guide to how CTE mismatch causes adhesive bond failure. Contamination risk: Material that squeezes into internal passages can break loose later and cause blockages or wear. What to Use Instead Industrial joints call for purpose-built sealing materials: Pre-formed gaskets in rubber, fiber, cork, metal, or PTFE, selected for temperature, pressure, and chemical compatibility on static seals. Liquid gasket makers such as RTV silicones and anaerobic sealants, which cure into resilient seals that fill microscopic voids and adhere to the flanges. Thread sealants such as PTFE tape and liquid pipe compounds for threaded connections. Structural adhesives where the joint needs both sealing and load-bearing strength. The rigid-versus-flexible trade-off there is covered in the comparison of UV glue versus epoxy for heavy-duty repairs. Selecting among these means considering fluid type, operating temperature and pressure, joint design, substrate materials, and required service life. Where Plumber's Putty Still Belongs The material is not defective, only misapplied when it goes onto industrial equipment. Its proper home is a non-pressurized, ambient-temperature, low-movement seal that may need to come apart by hand, such as a sink strainer body, a pop-up drain flange, or a faucet base against a sink deck. In those spots its non-hardening nature is the whole point: the fixture stays adjustable and removable indefinitely. It should still be kept away from natural stone and from certain plastics, where its oils can stain or embrittle the…