A heat sink bonded with the wrong adhesive can look mechanically sound for months before the real problem shows up as a slow, cumulative overheating trend rather than an obvious joint failure. Incure's Epo-Weld™ TC-9033 exists specifically to keep that bond line from becoming the weak link in a component's thermal path, pairing aluminum-filled thermal conductivity with the paste consistency that heat sink and cryogenic bonding actually require. An Aluminum-Filled Epoxy Built to Replace Non-Conductive Adhesives TC-9033 is a two-part, aluminum-filled epoxy engineered specifically for thermal management applications where a standard structural adhesive would otherwise create an unintended insulating layer between a heat-generating component and the surface meant to draw that heat away. Bonding a heat sink with a non-conductive adhesive doesn't just underperform — it actively works against the sink's purpose, trapping heat at the interface instead of letting it move through. TC-9033's aluminum filler gives the cured bond line meaningfully better thermal conductivity than an unfilled epoxy, while still delivering genuine structural performance: 12,000 psi flexural strength and 2,600 psi tensile shear at a Shore D70–D80 cured hardness, figures that hold up under the mechanical vibration and thermal cycling that power electronics assemblies see in continuous service. Thixotropic Paste Consistency Solves a Real Dispensing Problem TC-9033's thixotropic paste consistency is a deliberate process choice, not an incidental property. A flowable adhesive is efficient on a flat, well-defined bond line, but it runs or sags on a vertical surface or an irregular heat sink fin geometry before it has a chance to cure — exactly the situation TC-9033 is formulated to avoid. The paste holds its shape and stays where it's placed, which matters on assemblies where the bond geometry isn't a simple flat interface, or where the joint has to be positioned and held without an oven step available to lock it in early. That same consistency gives TC-9033 genuine gap-filling capability, bridging minor surface irregularities between a heat sink and a component rather than requiring both mating surfaces to be machined to a tight, uniform tolerance before bonding. Email Us with your heat sink geometry and bonding process, and Incure's engineers can confirm whether TC-9033's paste consistency fits your application. NASA Outgassing Compliance Opens Up Cryogenic and Vacuum Assembly TC-9033 meets NASA outgassing requirements, a specification that matters well beyond aerospace work. Any bond line inside a sealed or vacuum enclosure risks off-gassing volatile compounds over time, and that off-gassing can redeposit as contamination on nearby optics, sensors, or electrical contacts — a slow-developing failure mode that's difficult to trace back to the adhesive once it's already caused a problem. That makes TC-9033 a fit for cryogenic component bonding and other sealed-enclosure assemblies where the adhesive needs to hold a structural bond without becoming a long-term contamination source for whatever sensitive equipment shares the same sealed space — the manufacturer's own catalog names cryogenic components specifically among TC-9033's intended applications, alongside general heat-sink bonding for power electronics. Cure Schedule Trades Oven Capacity for Cycle Time TC-9033 cures…

A high-power resistor that runs hot enough to need protection also runs hot enough to punish the wrong protection choice — a thick potting compound that traps heat instead of shedding it can push a component past its thermal limit faster than leaving it uncoated. Incure's Epo-Weld™ HTEC-202 solves that specific tension: a light gray ceramic coating engineered to insulate electrically while adding almost no thermal resistance of its own. A Thin Dielectric Coating, Not a Thick Potting Compound HTEC-202 is a low-viscosity, single-component ceramic coating rather than a bulk encapsulant, and that distinction is the point. Where a thick potting compound protects a component by burying it — at the cost of trapping the heat that component needs to shed — HTEC-202 forms a thin dielectric layer that provides electrical insulation without significantly impeding thermal dissipation. That makes it suited specifically to components that generate heat as part of normal operation, like high-power resistors and rheostats, where the coating's job is to prevent electrical leakage and shorting without becoming the thing that causes the component to overheat. Built for Dip-Coating, Not Dispensing HTEC-202's thixotropic paste consistency is formulated for dipping resistors and coating heating coils rather than bead dispensing along a defined path. That process fit matters on a production line: a resistor or coil geometry with an irregular surface — windings, leads, mounting tabs — is often faster and more consistent to dip-coat than to trace with a dispensing needle, and the paste's thixotropy keeps it from running off vertical or irregular surfaces before cure the way a thinner liquid coating would. The tradeoff is that dip-coating suits batch processing of small-to-mid-size components better than it suits large or oddly shaped parts that would need an impractically large dip tank. Email Us with your component geometry and coating process — dip, brush, or another application method — and Incure's engineers can confirm whether HTEC-202 fits your line. Stability to 2600°F, With a Straightforward Room-Temperature Cure HTEC-202 maintains its dielectric integrity and mechanical properties up to 2600°F, preventing the coating breakdown and electrical leakage that would otherwise develop as a resistor cycles through repeated heating and cooling in service. That ceiling is paired with a Shore D80 cured hardness, 9,500 psi flexural strength, and 2,100 psi tensile shear — a rigid, durable coating rather than a flexible one, appropriate for a protective shell that isn't expected to absorb joint movement the way a structural bonding adhesive would. Cure is a straightforward 24 hours at 77°F, with no oven step required, which keeps HTEC-202 usable in facilities without a high-temperature cure oven dedicated to this step. Durability Against Moisture and Thermal Cycling in Service A dielectric coating that only performs on the test bench isn't doing its job — a resistor or rheostat in service sees repeated heating and cooling as load varies, plus whatever ambient humidity or condensation the enclosure exposes it to, and the coating has to maintain adhesion and dielectric integrity through both. HTEC-202 is formulated to…

A structural bond only has to do two things well: hold under load and reach every surface it's supposed to reach before it cures. Incure's Uni-Weld™ 1013 is built around that second requirement as much as the first — a low-viscosity urethane acrylate that flows into tight, precision joints by capillary action rather than requiring a syringe to force it into place, then cures to a tensile bond strength that outperforms most of its own product line. A Tensile Strength Leader, Not an Elongation Leader Within Incure's broader Uni-Weld™ multi-substrate bonder lineup, elongation varies enormously by grade — some formulations stretch past 700% before failure, others stay under 5% for rigid, dimensionally stable joints. Uni-Weld™ 1013 sits in between at 50% elongation, giving a bonded joint enough give to absorb shock and vibration without behaving like a rigid, crack-prone glass line. Where 1013 actually distinguishes itself is tensile strength: 7,100 psi on plastic substrates and 4,100 psi on metal and glass, both figures among the highest in the entire line rather than a middling compromise. The plastic-substrate figure is limited by the substrate's own fracture point rather than the adhesive's ceiling, meaning the bond itself is typically stronger than the plastic part being joined — a useful distinction when specifying an adhesive against a material that might fail before the bondline does. That combination — moderate flex, leading tensile strength — makes 1013 a better fit for joints that need to survive mechanical loading in service than for joints whose primary requirement is absorbing continuous flex. Low Viscosity Built for Wicking Into Precision Joints At 550 to 1,100 cP, Uni-Weld™ 1013 runs thin enough to wick into narrow gaps and capillary joints under its own flow rather than needing to be packed or dispensed under pressure — a property that matters most on precision assemblies where the bondline is too small or too enclosed to access with a dispensing needle after the parts are mated. Optical fiber splicing is a direct beneficiary: the adhesive draws into the splice point around the fiber rather than requiring the joint to be built around adhesive access. Wearable device assembly sees the same advantage on a different scale, where enclosures and internal components are staked together in gaps too tight for conventional bead dispensing. Combined with the line's characteristically fast UV cure, that wicking behavior reduces cycle time on high-throughput precision assembly lines where a bead-and-clamp process would otherwise bottleneck the line. Email Us with your joint geometry and substrate pairing, and Incure's engineers can confirm whether Uni-Weld™ 1013 fits your assembly process. Mixed-Substrate and Wide-Temperature Service Rated from −55°C to 80°C, Uni-Weld™ 1013 spans cold-storage and outdoor-exposure conditions on one end and elevated ambient or under-hood service on the other, without requiring a substrate-specific reformulation at either extreme. That range matters most on mixed-substrate assemblies — plastic bonded to metal or glass — where the two materials expand and contract at different rates across a thermal cycle. The 50% elongation gives the bondline…

An organic paint on a furnace manifold doesn't fail gradually at high temperature — it carbonizes, and once that happens the coating stops protecting the metal underneath entirely rather than just degrading in performance. Incure's Epo-Weld™ HTSG-791 solves that failure mode with a genuinely different chemistry: a silicone binder filled with glass frit that fuses into a continuous barrier when heated, rather than a coating that simply tolerates high temperature without actively transforming under it. Glass Frit Fusion Is What Separates This From an Ordinary Silicone Coating HTSG-791 cures by a single 1-hour cycle at 400°F, and that heat step isn't just curing the silicone binder — it's fusing the glass frit filler into a continuous, glass-like protective layer, which is a fundamentally different mechanism than the room-temperature-cure silicone sealers elsewhere in Incure's catalog. A standard silicone coating stays a flexible polymer film regardless of service temperature; HTSG-791's glass frit component actually vitrifies during cure, producing a harder, more continuous barrier than a purely organic or silicone-only coating can achieve. That's also why HTSG-791 requires a genuine oven step rather than offering a room-temperature path — the fusion reaction that gives the coating its oxidation-resistant properties simply doesn't happen without reaching that temperature. It's supplied as a single-part, silver, viscous liquid at 400–800 cP, thin enough for brush or spray application, and cures to a Shore D70 hardness once the fusion step is complete — a genuinely rigid finish compared to the softer, more flexible elastomeric films typical of room-temperature-cure silicone products. Built Specifically to Stop Oxidation, Not Just Seal a Surface HTSG-791 is rated to 1400°F and formulated to prevent the specific failure modes that show up on unprotected metal and ceramic in that service range: surface scaling, oxidation pitting, and chemical corrosion, rather than the more general moisture-and-weathering protection a typical protective coating targets. It also resists moisture, acids, alkalis, and salts directly, and doubles as a sealer for porous ceramics, extending the service life of refractory materials that would otherwise degrade from surface porosity letting corrosive atmosphere reach deeper into the material. It's also RoHS compliant, relevant for any facility with existing procurement standards around restricted substances even on industrial process equipment that doesn't fall under consumer-electronics compliance requirements directly. That combination — active oxidation protection on metal plus porosity sealing on ceramic — is what makes HTSG-791 suited to furnace components and exhaust manifolds specifically, assemblies that routinely combine both substrate types in the same service environment. The oxidation-pitting failure mode it targets is a real distinction from ordinary corrosion: pitting concentrates material loss at small localized points rather than eroding a surface evenly, and a coating that only slows general corrosion without actually stopping localized oxide penetration can still let a component fail early at just a few weak points even while the rest of the surface looks intact. Email Us with your substrate, service temperature, and whether oven capacity is available for the required cure step, and Incure's engineers can confirm whether Epo-Weld™ HTSG-791…

A thin dielectric sealer that's perfect for coating a flat electronic assembly runs straight off a vertical furnace wall before it has a chance to cure, and a thick, non-sagging paste made for filling a large void is needlessly heavy-handed on a simple flat seal. Incure's Epo-Weld™ high temperature silicone sealer line solves that mismatch with three grades that share identical mechanical and electrical properties and differ almost entirely by viscosity — a genuine viscosity ladder rather than three products competing on strength or temperature rating. All three are also single-part, room-temperature-cure formulations, so there's no mixing ratio or pot life to manage on the shop floor regardless of which viscosity a job actually calls for — the only real decision is where the joint sits on that ladder. A Three-Step Viscosity Ladder From Thin Coating to Non-Sag Paste HTSS-260 sits at the thin end at 200–300 cP, a clear, flowable sealer built for coating ceramics, metals, and glass in electronic assemblies where a thin, even hydrophobic film matters more than gap-filling capacity. HTSS-261 steps up to 2,000–4,000 cP specifically to solve the problem HTSS-260 can't — sealing porous ceramics and refractories on vertical surfaces, where a low-viscosity sealer would run off before curing. HTSS-263 goes further still to 18,000–25,000 cP, a very high-viscosity paste engineered to stay exactly where it's placed during application and cure, built for filling large voids and gaps in ceramic insulators rather than coating a surface at all. Moving up that ladder trades flowability for gap-filling and vertical stability, and picking the wrong end of it means either watching a thin sealer run off a vertical joint or applying a thick paste where a simple flat coating would have worked just as well with less material and easier application. The roughly two orders of magnitude separating HTSS-260's thinnest rating from HTSS-263's thickest is a wider spread than viscosity variants typically show on Incure's other product lines, reflecting how differently a coating film, a vertical seal, and a void-filling paste actually behave during application even before cure begins. Mechanical and Electrical Properties Stay Identical Across All Three All three grades share the same Shore D80 hardness, 9,600 PSI flexural strength, 1,600 PSI tensile shear, 800°F temperature ceiling, and 24-hour room-temperature cure — none of that changes as viscosity climbs from HTSS-260 to HTSS-263. Each also delivers the same dielectric strength and flexibility, preventing electrical leakage and prohibiting the coating from fracturing under thermal stress, and the same resistance to humidity, chemical vapors, and UV exposure. That consistency is what makes viscosity the entire selection variable here — a facility isn't trading away strength, temperature rating, or electrical protection by choosing the thinner grade for a flat seal instead of defaulting to the thicker paste out of caution. Email Us with your joint orientation — flat, vertical, or a void that needs filling — and Incure's engineers can confirm which Epo-Weld™ silicone sealer viscosity actually fits. Matching Each Grade to the Joint It Was Actually Built For…

A thermal interface grease at a heat sink joint has to solve the same basic problem every time — eliminate the air gap between two mating surfaces so heat actually transfers instead of stalling at the interface — but whether that joint also needs to carry electrical current or ground a connection changes which filler metal actually belongs in the grease. Incure's Epo-Weld™ thermally conductive grease line covers both cases across three grades, unbonded and reworkable rather than curing into a permanent joint the way an adhesive does. TCG-10 Moves Heat While Staying Electrically Insulating Epo-Weld™ TCG-10 is an alumina-filled grease built specifically to conduct heat while remaining electrically insulating — a combination that matters directly for mounting transistors and rectifiers, where the thermal interface sits close to live circuitry and can't become a path for current leakage or signal interference. It maintains stable, non-drying performance up to 550°F, holding its consistency at the heat sink interface rather than separating or hardening over sustained thermal cycling the way a lower-grade grease would. That non-drying behavior matters specifically because a grease that hardens or crumbles over time reintroduces the same air-gap problem the grease was applied to eliminate in the first place — an interface that looks fine at initial assembly can quietly lose most of its thermal performance months later if the filler system doesn't hold up under repeated heating and cooling. TCG-30 and TCG-40 Both Conduct Heat and Current, Split by Filler Metal Epo-Weld™ TCG-30 and TCG-40 take the opposite approach from TCG-10, both formulated to conduct heat and electricity simultaneously through the same interface — the property TCG-10 is specifically built to avoid. TCG-30 uses aluminum filler for grounding connections and high-power electrical contacts, providing a low-resistance path for both current and heat at a moderate cost. TCG-40 steps up to copper filler, delivering genuinely lower contact resistance and better electrical conductivity than aluminum, positioned for high-current switches and grounding lugs where minimizing voltage drop across the interface is the primary requirement rather than a secondary benefit. That's the same cost-versus-performance trade-off found in Incure's thermally and electrically conductive adhesive line, just applied to a non-curing grease interface rather than a permanent structural bond — aluminum for cost-effective general-purpose conductivity, copper where contact resistance genuinely needs to be minimized. Both also resist moisture and oxidation, keeping their conductivity stable rather than degrading as the metal filler itself corrodes over years of service — a genuine concern on any grease relying on a bare metal filler for its conductive path, since an oxide layer forming on the filler particles would raise contact resistance right at the interface the grease exists to protect. Email Us with your interface's electrical requirement — insulating or conductive — and whether cost or minimum contact resistance matters more, and Incure's engineers can confirm which Epo-Weld™ thermally conductive grease grade actually fits. Same Mechanical Profile Across All Three, Filler Chemistry Is the Only Real Variable All three grades share the same thixotropic paste consistency and…

Most adhesives get applied straight from the container, but an inorganic binder is often the raw ingredient a formulator mixes into a custom refractory cement, coating, or casting compound — the binder itself isn't the finished product, it's what holds the finished product together. Incure's Epo-Weld™ high temperature inorganic binder line spans ten grades built for that formulation role, plus a smaller group of phosphate-bonded grades structural enough to function as finished potting and casting compounds in their own right. Five Liquid Binders Formulate Custom Refractory Cements and Coatings HTIB-101, 104, 105, 109, and 116 are all liquid inorganic binders used to formulate custom high-temperature cements, coatings, and wash coats rather than applied as a finished product on their own — differentiated mainly by viscosity and chemistry. HTIB-104 runs thinnest among this group at 200–500 cP, built for thin-film coatings and deep impregnation of porous substrates. HTIB-101 sits at a general-purpose 400–800 cP for formulating custom refractory cements and potting compounds broadly. HTIB-109 shares that same 400–800 cP range and is built for deep impregnation and sealing of porous ceramics and fibrous insulation — worth noting precisely because it isn't actually the lowest-viscosity grade in this group despite its own description emphasizing penetration; HTIB-104 and, further below, HTIB-110 both run thinner. HTIB-105 steps up to 600–1,000 cP with high alkalinity specifically for stabilizing dispersions of basic refractory oxides like magnesia and alumina, preventing the settling and agglomeration a less compatible binder would allow. HTIB-116 is the thickest of this group at 3,000–4,000 cP and chemically distinct — an acidic alumina binder formulated to avoid silicon contamination entirely, positioned specifically for nuclear and aerospace applications where that purity requirement is non-negotiable. 110 Is a Standalone Fiber-Rigidizing Binder, the Thinnest in the Line HTIB-110 breaks from the formulation-ingredient role of the five grades above it: a colloidal silica binder at just 10–20 cP — genuinely the thinnest grade in the entire line — built specifically to rigidize and harden refractory fiber boards and blankets. Rather than being mixed into a new compound, it's applied directly onto a soft, friable fiber surface to convert it into a hard, erosion-resistant shell that stops dusting at elevated temperature. That's a meaningfully different job than the five formulation binders above: those are ingredients for building something new, while HTIB-110 treats and strengthens a surface that already exists. Email Us with your formulation goal, target viscosity, and whether the binder needs to go into a new compound or treat an existing surface, and Incure's engineers can confirm which Epo-Weld™ inorganic binder grade actually fits. Four Phosphate-Bonded Grades Are Structural, Not Just Formulation Ingredients HTIB-117, 118, 125, and 126 all carry real cured mechanical specs — Shore D80–D85 hardness and roughly 9,600–10,500 PSI flexural strength — setting them apart from the liquid formulation binders above, which mostly show no hardness or flexural rating at all since they're additives rather than finished materials. HTIB-117 is built for the investment casting industry specifically, replacing standard colloidal silicas in shell building…

An ordinary hydrocarbon grease lubricates a joint just fine at atmospheric pressure and then quietly sabotages a vacuum system the moment the pump starts pulling — the grease itself outgasses into the chamber, extending pump-down time and contaminating anything sensitive nearby. Incure's Pyra-Sil™ 802 high vacuum silicone grease solves that specific problem, formulated for the demands of vacuum, pressure, and chemical processing equipment rather than general mechanical lubrication. Low Volatility Is the Property That Actually Matters in Vacuum Service Standard greases contain volatile components that evaporate under reduced pressure, releasing vapor into the very vacuum a system is trying to maintain — a failure mode that shows up as longer pump-down times, unstable base pressure, or contamination redepositing on nearby optics and sensitive surfaces. Pyra-Sil™ 802's exceptionally low volatility is what actually distinguishes it from a general-purpose grease, keeping the formulation stable rather than slowly evaporating into the chamber it's meant to seal. Its thixotropic gel consistency reinforces the same goal from a different angle: it stays exactly where it's applied on a vacuum flange or O-ring rather than migrating or dripping away under gravity, which matters as much on a joint that sits in the same position for years as it does during initial application. That combination of properties is also why substituting a general-purpose grease into vacuum service, even one that seems mechanically similar on a datasheet, is a genuine risk rather than a minor compromise — the volatility difference doesn't show up until the system is already under vacuum and the base pressure won't stabilize where it should. A Wide Service Range Covers Cryogenic to Elevated-Temperature Process Equipment Rated from −45°C to 204°C, Pyra-Sil™ 802 spans both ends of the temperature range vacuum and process equipment actually operates across — cold enough for cryogenic fitting seals that see genuinely low service temperatures, and hot enough for chemical process equipment running well above ambient. That range matters because a grease formulated only for room-temperature service can stiffen and lose its sealing conformability in cold service, or soften and migrate away from the joint in hot service — either failure mode defeats the purpose of applying it in the first place. A single grease covering both ends of that range simplifies inventory on a facility running equipment across genuinely different thermal environments, rather than stocking separate greases for cold and hot service. Email Us with your service temperature range and application — sealing, lubrication, or both — and Incure's engineers can confirm whether Pyra-Sil™ 802 fits your vacuum or process equipment. Five Applications, One Grease O-ring and gasket lubrication is the most routine use, reducing friction and wear on seals that get opened and reseated repeatedly, extending the O-ring's own service life rather than letting dry friction degrade it prematurely with each cycle. Vacuum flange sealing draws on the same thixotropic gel behavior to fill microscopic surface irregularities on a flange face, improving the seal beyond what metal-to-metal or elastomer-to-metal contact alone achieves. Valve and stopcock lubrication in laboratory…

A standard cyanoacrylate bond can fail well before the substrate itself is under real thermal stress — the adhesive's own glass transition point, not the parts being joined, is often the actual limiting factor. Incure's Heat-Resist™ line addresses that directly with five rubber-toughened, single-component ethyl cyanoacrylate grades built specifically for thermal shock resistance, organized around viscosity and substrate scope rather than one shared "high-temp CA" spec. Rubber toughening is the shared chemistry behind the whole line's thermal-shock resistance: a standard, unmodified cyanoacrylate cures into a rigid, brittle film that cracks under the stress of rapid temperature swings, while the rubber-modified formulation flexes enough to absorb that stress at the bond line instead of transmitting it straight into a fracture. Two Viscosity Pairs, Each Available in Black or Clear Heat-Resist™ 311 and 340 share the same high viscosity (2,000–3,000 cP) and the same broad substrate scope across plastics, rubber, metal, fiberglass, ceramic, and wood — the widest bonding range in the line — plus the highest temperature ceiling at 145°C. The two differ only in color: 311 is black, 340 is clear, letting a line pick based on whether bond-line visibility matters for inspection or cosmetic reasons rather than on any mechanical difference. Heat-Resist™ 319 and 328 form a second matched pair at medium viscosity (400–600 cP), again split by color — 319 black, 328 clear — but with a narrower substrate focus on plastics and metal rather than the full six-substrate range of the 311/340 pair, and a slightly lower temperature ceiling at 135–140°C. Choosing between the two pairs comes down to whether the joint spans the broader substrate range or stays within plastic-to-metal bonding, since the medium-viscosity pair doesn't carry the same rubber, fiberglass, ceramic, or wood bonding claim. 320 Is the Thinnest, Fastest-Wicking Grade in the Line Heat-Resist™ 320 stands alone as the thinnest grade at just 260–370 cP, thin enough to wick by capillary action into an already-assembled tight joint rather than requiring the parts to be coated before mating — the same low-viscosity wicking behavior found in Incure's UV-cure gasket lines, just applied to cyanoacrylate chemistry here. It shares the medium-viscosity pair's plastic-and-metal substrate focus, but its temperature ceiling drops slightly further to 135°C, the lowest in the line. That combination makes 320 the grade to reach for on fine-gap assembly work where a thicker grade would sit on the surface rather than flow into the joint, provided the application doesn't need the higher-viscosity grades' extra 10°C of thermal headroom. Because 320 only comes in black, a line that needs both wicking viscosity and bond-line clarity for inspection has to choose one property over the other — no clear, low-viscosity grade exists in this line the way one does at the medium- and high-viscosity tiers. Email Us with your substrate combination, joint geometry, and service temperature, and Incure's engineers can confirm which Heat-Resist™ grade actually fits. Shared Chemical Resistance and Bond Strength Across the Line All five grades deliver the same headline bond strength figures —…

A UV-cure adhesive fixes instantly wherever light reaches it and does nothing wherever it doesn't — which is exactly why a dual-cure silicone that finishes shadowed areas by moisture exposure solves a real problem on any assembly with a housing, an overlap, or a connector blocking the light path. Incure's Pyra-Sil™ UV silicone line covers that dual-cure need across four grades, plus one grade that breaks from the UV-cure pattern entirely. 901 and 904 Are a Viscosity-Matched Pair for General-Purpose Bonding Pyra-Sil™ 901 and 904 are both one-part, UV/moisture dual-cure, high-temperature silicones formulated for bonding a wide range of substrates as form-in-place gaskets, conformal coatings, and sealants — UV light fixes exposed surfaces fast, while ordinary moisture in the air fully cures whatever the light couldn't reach within 72 hours. The two share the same -45°C to 260°C service range and dual-cure chemistry, differing mainly in viscosity and hardness: 901 runs thicker at 6,500–8,500 cP and cures to Shore A30–A40, while 904 is noticeably thinner at 2,000–3,000 cP and softer at Shore A20–A30. That gives a line running general-purpose bonding and sealing work a genuine choice between a heavier-bodied grade that holds its shape on a gap or seam and a thinner one that flows more readily into finer features, without giving up dual-cure convenience either way. Both are compatible with manual dispensing and automated or spray equipment, so the viscosity choice is driven by the joint geometry itself rather than by what equipment the line already runs. 905 and 909 Add High-Altitude Arcing Protection on PCBA, at a Softer Hardness Scale Pyra-Sil™ 905 and 909 are also a matched dual-cure pair, but they're built specifically as a conformal coating for PCB assemblies, protecting against moisture, ozone, and — notably — high-altitude arcing, a failure mode specific to circuit boards operating at reduced atmospheric pressure where dielectric breakdown happens more readily than at sea level. Both cure on the O-scale rather than the A-scale used by 901 and 904 — 905 and 909 both land at O65–O95, a softer, more gel-like hardness measurement suited to a thin conformal coating rather than a structural gasket material. The two differ mainly in viscosity: 905 is the thinnest grade in the entire line at 350–750 cP, suited to spray or dip coating over populated boards, while 909 runs thicker at 2,500–3,500 cP for more controlled bead or brush application. Both fix under UV light in seconds and fully cure shadowed areas by moisture within 72 hours, the same dual-cure logic as 901 and 904 but tuned specifically for board-level electronics protection. The arcing-protection framing is worth taking seriously as a real selection factor rather than boilerplate marketing language — a board that never leaves sea level doesn't need it, but one destined for aerospace, high-altitude telecom, or any enclosure that depressurizes in service does, and the general-purpose 901/904 pair doesn't make the same claim. Email Us with your substrate, service temperature, and whether the assembly has shadowed areas UV light can't reach, and…