Trondak U-40 LS Supreme High Build review- Part I
Note: I bought the High Build version of U-40, not the regular. Whenever I say "U-40" in the following report, I'm referring to U-40 LS Supreme High Build. The same thing for Flex Coat: when I say Flex Coat I'm talking about Flex Coat Ultra V.
I read somewhere that a lot of the epoxies out there are the same thing, only in different packaging. This cannot be said of U-40. The resin component is much thicker than the resin in Ultra V, while the catalyst is slightly thinner. While mixing, I also noticed that U-40 has a stronger smell than Flex Coat.
Mixing: I did a little experimenting, and so far U-40 seems to mix best when I mix it the same way I mix Flex Coat. My technique is mix 1 minute, heat, and then keep mixing, heating at intervals of 45 seconds until you have mixed for a total of 4 minutes. Do not count the time heating as part of the four minutes. After mixing, heat the epoxy one final time and then cover it and let sit for ten minutes.
Viscosity: U-40 is considerably thicker than Flex Coat, and so you can probably use fewer coats. For example, if you use three coats of Flex Coat, you can probably use only two coats of U-40.
Bubbling: In my limited experience, U-40 appears to bubble more than Flex Coat. But on the package, it says to pour the mixed epoxy on a piece of foil, and I haven't been doing that. I will pour it out in the future to see if that fixes the bubbles.
Heating: U-40 doesn't react to heat the same way Flex Coat does. Heating Flex Coat while mixing will pop a lot of the bubbles, and at the end of the ten minutes most of the bubbles are gone. When I heated U-40 a lot of the bubbles would pop, but I still had quite a few bubbles in the mixed epoxy. More of the bubbles popped when I was brushing the epoxy on, but it for me it hasn't been as bubble-free as Flex Coat. Also, heating U-40 after it's on the lure doesn't do much to remove bubbles; it will pop some of them but it will also generate more.
Dry Time: U-40 sets up faster than Flex Coat, and is dry to touch in 4-6 hours. Flex Coat takes longer, usually 6-8 hours to dry. However, Flex Coat appears to cure faster than U-40, and after two days of cure time for each Flex Coat is a little harder than U-40 mixed on the same day. On the package it says that U-40 takes 5 days to fully cure, so I'll see how hard it is then.
Appearance: U-40 gives a beautiful, glossy finish very similar to Flex Coat.
Yellowing & Durability: I haven't had U-40 long enough to know how well it resists yellowing and teeth marks, but I'll try to post info in the next part of my review. That could take several weeks, so stay tuned.