Talking to experts built my confidence - I'm going to try for composite baffles, done with high temp epoxy. Klaus uses an aerospace product I can't access, so when pressed for a recommendation he offered: - make sure it's a laminating epoxy and test the sample with a scratch test. There will be a transition temperature where it goes from a hard ceramic-type scratch result to something like a rubber sheet. That transition is the measured temperature for this use. - The outer edge of a cylinder fin will be a lot cooler than 400 degrees - closer to 200. - An epoxy with a two-stage curing cycle has a chance of meeting the standard. He likes MGS. I have West, Aeropoxy, Max HTE (high temp), Max GRE (fuel resisistant) and a number of general purpose epoxies. Only the Max HTE comes anwhere close to the target temperatures, so I'll make a test blank with it, then stress test a toaster oven! Here's the write up on Max HTE: MAX HTE A/B is a two-part epoxy based system especially formulated to provide structural strength at temperatures of up to 200⁰C or 390⁰F under pressure or load. It is formulated as an impregnating resin for fiberglass, Carbon Fiber, Kevlar, Spectra Fiber and other specialty materials that require heat performance. MAX HTE A/B can also be utilized as an adhesive, encapsulant or potting compound, tooling resin for high temperature applications. MAX HTE exhibits exceptional toughness and other mechanical properties such as adhesion, compressive strength and flexural modulus at high temperature exposure. MAX HTE also provides excellent chemical and water resistance. Fillers and colorants can be added to modify it for a specific use. MAX HTE provides a long pot life at room temperature suitable vacuum assisted resin transfer molding or VARTM, fiber pultrusion, pre-impregnation process with a relatively short heat cure time. It is specially designed to withstand continuous high temperature service, high impact resistance and exposure to harsh conditions. MAX HTE A/B is 100 % solids, low odor and toxicity and does not contain Ozone Depleting Chemicals (ODC).