Adhesion Matters - Aerospace Sealants (PPG)

Episode Date: August 3, 2025

PPG's aerospace business is a leading provider of high-performance coatings, adhesives, sealants, transparencies, and engineered materials. With a strong emphasis on quality, reliability, sustainability, and innovation, PPG offers tailored solutions for aerospace OEMs, engineers, defense contractors, and MRO (Maintenance, Repair, and Overhaul) shops. Key areas of focus include advanced sealant application methods (especially 3D printing), high-strength adhesives, protective coatings, and specialized materials for demanding aerospace environments. In this episode, we will talk about their commitment to enhancing aircraft performance, durability, safety, and operational efficiency, while also supporting environmental responsibility through waste reduction and lightweight solutions.

Have you ever really stopped to think about what keeps an airplane? Well, up there, flying safely, efficiently. We often think about the engines, the wings, the pilots. But there are these silent heroes, these unseen materials that are absolutely critical. Today we're doing a deep dive into that world advanced materials and innovative tech, specifically focusing on aerospace sealants and adhesives from a company called PPG. And just so you know, our information for this dive comes straight from PPG's own stuff, their websites, their product guides, even transcripts from their videos.

Yeah, and our goal today, our mission, if you like, is to really uncover how these specialized materials aren't just, you know, parts on a list. They're actually critical enablers. They're transforming how aircraft are built, maintained, even defended. We're talking about driving big improvements in efficiency, safety, and maybe surprisingly sustainability, too. It's really shaping the future of flight. Okay, let's unpack this then, because looking through the material, it seems

PPG isn't just doing one little thing. They seem to be involved in, well, almost everything, aerospace. That's what's really fascinating. They've kind of positioned themselves as this comprehensive, one-stop shot for aerospace materials. Their portfolio is huge. It covers coatings, adhesives, sealants, engineered materials, special packaging, even transparencies like the cockpit windows. This means they're involved across the board, commercial jets, regional planes, military aircraft, general aviation. And importantly, especially for military stuff, they support the entire life cycle, right for manufacturing through all the maintenance, repair, and overhaul the MRO work.

And it's more than just the materials themselves, right? I saw they offer support services, too, like training academies, design labs, support centers globally. Exactly. Things like their Aerospace Academy for Training, the livery lab for design help, and application support centers around the world. They get to the material as only part of the equation. Applying it right is crucial. Okay, so they've got this wide reach, but let's pivot to something that sounds, well, honestly, like science fiction. 3D printing ceilence for airplanes.

That sounds wild. How do that even work? Why is it such a big deal? Right. It does sound futuristic. But if you look at the bigger picture, this innovation, it's not just about doing things faster, it's a huge leap in precision and like we mentioned, sustainability. It tackles some really old, tricky, labor-intensive problems in aerospace manufacturing. manufacturing. PPG calls the technology ambient reactive extrusion or R. Basically, it lets them

3D print, preform sealants in gaskets. So instead of manually applying goopy sealant, smoothing it, trimming it, all that rework, you get a perfectly shaped part ready to go. And it's not just experimental. Some of these parts even have a national stock number in NSN, which is a big deal for military use. It means they're standardized, reliable. Wow. Okay. Preformed precise parts. So beyond just being faster, what are the main advantages? What makes this so revolutionary? Yeah, the benefits are pretty compelling. First, as you guessed, accelerated installation times, we're talking reductions of up to 90%. Parts can go on maybe 10 times faster. A ton times fast. Yeah, huge. Which means less downtime for the aircraft. Second, there's potential

cost savings. Less labor, less wasted material because you print exactly what you need. That ties into the third point. Sustainability. You're virtually eliminating material waste during production. That's a big plus environmentally. And finally, probably most importantly, unmatched precision and quality. You get uniform, consistent, dimensionally perfect parts, less rework, higher safety, higher performance right off the bat. That precision must be key. So where are these 3D printed seals actually being used on an aircraft? Oh, all sorts of critical places. Think about fuel tanks. You absolutely need a perfect leakproof seal there. Also wing seals, which helps with aerodynamics and structural integrity.

Door and window seals, obviously important. They can be used as thermal barriers, protecting sensitive stuff from heat. And for custom seal caps, maybe unique shapes that are hard to do manually, plus other specific spots like wing pads, cockpit seals, gap fillers, even simple O-rings, but made with incredible precision. And getting one of these parts made, it sounds pretty straightforward, like a four-step process. Yeah, they align it pretty simply.

Starts with Discovery, they check out the situation on-site, then design, using CAD or a laser scans, then they make a prototype for fit checks and testing. And finally, if everyone's happy, on-demand production delivery. It's quite agile for a physical part. And the sealant material itself, what are its key properties? Right. So material has to perform. These are rapid cure, high-performance sealants. They said quickly, but stay flexible, good, elastomeric properties. They have excellent resistance to jet fuels like PR-2001, which meets tough specs like AMS 3277. And they also stand up really well to water. alcohols, hydraulic fluids, lubricating oils, basically the harsh stuff found on an aircraft.

It's just incredible how specialized everything is. It really is like a toolkit where every single tool is designed for one very specific job on the plane. It really is. Yeah. And that raises the question, doesn't it? How do all these different materials with different properties work together to make the whole aircraft resilient and perform it? I mean, you've got their foundational brands, PRC, and ProSeal. They're used all over fuel tanks. Stopping corrosion, smoothing surfaces for aerodynamics, electrical insulation, ceiling windshields. But then you drill down and you find even more specific types for unique challenges. Like what? Give us some examples. Okay, take fuel tank ceilons. There's one called HTS-9-410-0 Class

S. It's fast-curing, sprayable, a three-part polysulfide sealant used inside and outside tanks, but it also helps protect landing gear. And its temperature range is huge, minus 55 Celsius, up to 120C. Wow. Then there's PR 1198. It's a sprayable polyurethane coating. Think of it like a secondary safety layer on the outside of a wing box, just in case of leak. It cures clear and stays flexible. And firewalls, obviously critical for safety. Absolutely critical. For that, they have PR 812. It's a high-temps synthetic rubber, seals against air and vapor. Service ranges negative of 65 to 400 Fahrenheit, but it can handle flashes up to 2,000 degrees F. Really heavy-duty stuff. Okay. What else? Any other really specialized examples?

Well, there are electrically conductive sealants, like PR 2225 Class B. It's filled with nickel conducts electricity well. That's important for EMIRFI shielding, protecting electronics from interference, and also acts as a corrosion barrier, good up to 300 Fahrenheit. Or for aerodynamic smoothing, filling tiny gaps to reduce drag, there's PR 2050 Class B. It's a polytheoether compound, cures fast sandable in an hour, stays flexible, resist fuel and fluids, and crucially has low shrinkage, so the surface stays perfectly smooth. They even seem to have things for wiring and connectors. They do. That's where potting and molding compounds come in, like the PR-1500. series. These are polyurethanes used to basically encase electrical connectors and cables. They need

high dielectric strength, good insulators, plus abrasion resistance and hydrolytic stability, meaning they don't break down easily with moisture. And one more for quick jobs needing fuel resistance, maybe in chemical tanks. There's PRC Rapid Seal 901. Apoxicured polytheoether. Low odor. Cures fast even when it's cold and humidity doesn't affect its cure rate. Okay, so moving from sealing to sticking things together. Adhesives. It's clear this isn't just like using glue, right? It's fundamental to making aircraft lighter and safer. Absolutely. And this really shows how material science directly impacts those big things. Fuel efficiency, safety, these are top priorities in aerospace. Take their ballistic armor adhesive systems BAS, specifically PR 2930. This

isn't just strong glue. It's described as a state-of-the-art structural adhesive. Performs in harsh conditions meets tough military specs like Mill, STD, 3, or a 5-9 Group I. What that means for you is it's designed for high-impact situations, directly helping protect personnel in military aircraft. And I saw something about ESPAs, epoxy syntactic paste adhesives. Yes, ESPAs like the PR-2940 series. These are interesting. They're used for joining, filling, and reinforcing honeycomb structures and panels.

You find those honeycomb structures everywhere, wings, doors, inside the cabin in galleys, seats, overhead bins. They're super light but strong. So what are the advantages of using these ESPAs? There are quite a few. a few. First, strength and light weighting. They provide high mechanical strength and bond really well, but they're very low density. Max strength the weight ratio. That helps fuel efficiency. Second, safety. They're flame retardant, meeting FAR-25.853 rules. And they cure at room

temperature, which is safer for workers, less exposure to exothermic heat from the curing reaction. Third, versatility. Good solvent resistance. Various packaging options, cartridges, sem kits, pre-mixed frozen, suitable for hand or robotic application. And fourth, manufacturing optimization. They ensure precise mixing ratios and PPG can even help customers match their production line settings, like flow rate, ensuring consistency. And there was one more type mentioned, shimland adhesives. Right, like PR 2936. It's sort of a two-on-one, a liquid shim and an adhesive. It can fill gaps up to two millimeters while still being strong and flexible, and connecting back to earlier, it's also available in those 3D printed preform shapes.

Okay, so we've got all these amazing materials, but it sounds like just having the right stuff isn't enough. How you prepare, store, and apply it is just as critical. It's a real science, isn't it? It absolutely is. And this brings up an important point about human skill and procedure, even with all this automation. Understanding how to use these materials is vital for performance and safety. Surface preparation is huge. You need meticulous cleaning, often with specific solvents like diso-clean using careful techniques,

like progressive cleaning with fresh cloths to avoid just moving dirt around. And testing adhesion on the actual material you're bonding to is important. Plus, sometimes you need adhesion promoters, almost like a primer. They're strongly recommended for tricky situations, like repairing over old sealant that's soaked up fuel, or bonding to tough metals like titanium or stainless steel. And the packaging itself reflects different needs too, right? Cans, special kits? Exactly.

You've got the basic two-part can kits. Versatile, but you need to mix them really thoroughly by hand. and check carefully for any unmixed streaks or striations. Then there are SIM kit packages, much more convenient pre-measured, easier mixing in application. They have different styles, barrier, or injection, depending on the mix ratio, to make sure it's accurate. For high-volume use, pre-mixed and frozen PMF materials are often best.

Super convenient, just thaw and use. But, and this is a big, but they need serious cold storage, like negative 40 degrees F2 for polysulfides, maybe even 80 degrees FB for polytheoators and specific sawing procedure. Minus 80. Wow. Yeah, serious stuff. And then, of course, you have the preformed options we talked about, like form and place zip seal caps and the 3D printed parts.

An environment must play a role, too, like temperature and humidity affecting how fast they cure? Oh, definitely. It depends on the sealing chemistry. For example, standard manganese dioxide cured polysulfides. Low humidity actually slows the cure. High humidity speeds it up. But the chromate cured ones are barely affected.

affected by humidity. And those epoxy cured polytheo-avers, humidity doesn't impact their cure at all. Temperature, though, generally speeds up the cure for all types. Warmer means faster chemical reactions, so controlling the environment is key for consistent results. And last thing, cleaning up afterwards. Right. Practical point. Uncured sealant usually cleans up with a suitable solvent non-chlorinated is preferred. But once it's cured, you're usually talking mechanical removal, careful scraping, maybe gentle grinding, always being careful not to damage the surface underneath. PPG Semco, their packaging division, actually makes tools specifically for sealant removal and

smoothing too. It's all quite integrated. Well, this has been a really deep dive. We've gone from seeing PPG's huge footprint in aerospace materials acting as that one-stop shop, to the frankly amazing innovation of 3D printed sealants changing how planes are built and maintain, to understanding just how incredibly specific all these different sealants and adhesives are for every little job. And realizing that applying them correctly, that whole art and science, is just as vital as the material itself. So what does this all mean for you listening in? Well, next time you see a plane overhead or just think about the incredible engineering involved, maybe take a moment to remember these unseen heroes, these advanced materials, the science behind them, that are literally making

flight possible, safer and more efficient. And perhaps it sparks some curiosity. Maybe you'll look into how additive manufacturing, like 3D printing, is changing other industries too, or think about the material challenges facing the next generation of aircraft design. Because knowing that these kinds of advancements in precision, efficiency, and sustainability are happening right now, well, it really shows how innovation continues to shape the future of flight and maybe gives a deeper appreciation for the technology all around us.