At Aus Maker Supplies I'm always looking for ways to make life easier for makers. That means regularly reviewing what I stock to make sure it’s practical, reliable, and actually helps you get better results.
After lots of testing and customer feedback, we’ve decided to move away from Grade 310 stainless foil and focus on Grades 309 and 321. They’re both easier to use, and better suited for the kind of heat treating most makers do day to day.
Why 310 Is Getting Retired
There’s no denying that Grade 310 is high temp resistant. It handles the extreme heat and resists oxidation extremely well. The catch is that it’s very stiff and springy, which makes it a challenge to fold and crimp cleanly.
If you’ve ever tried to seal a knife packet and had the foil spring back or split at the edge, you’ve seen the issue. For most makers, that extra high-temperature capability just isn’t worth the hassle. And although it was cheaper we found the problems it gave our customers not worth the trade-off.
If you've ever bought a roll of 310 from me and aren't happy with it please reach out and I can give you a partial credit to either buy the new 321 or 309 foil.
309 For High-Temp Requirement Jobs
Grade 309 gives nearly the same temp performance as 310 but is much easier to work with. It seals neatly, folds smoothly, and still resists scaling at high temperatures.
If you’re running extended cycles or working with high-speed or high-alloy steels, 309 will give you the same protection with far less frustration. It’s now the go-to choice for high-temperature work.
Practical maximum service temperature:
~1090–1120°C (2000–2050°F) in continuous use
Shorter can go slightly higher for longer ~1250°C
321 For Medium-Low Temp Requirement Jobs
Perfect for Most Stainless steels with lower temp requirements, Grade 321 is the clear winner. It’s flexible, simple to fold, and more affordable than either 309.
It performs perfectly for the temperature ranges most makers work in and seals up without a fight. It’s also great for anyone doing smaller batches or looking for a reliable all-rounder.
Practical maximum service temperature:
~870–925°C (1600–1700°F) for long-term service.
Shorter can go slightly higher for longer ~980°C
Quick Comparison
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310: Too stiff and tricky to fold. Great temp performance but overkill for most users.
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309: The best choice for high-temperature work and long soak times.
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321: Easy to handle, affordable, and ideal for everyday heat treating.
Wrapping It Up
We’re not stepping back on quality. We’re just making it easier to get consistent results without wasting time or foil. 309 and 321 both protect your workpieces beautifully, giving you a cleaner and smoother experience at the forge or in the oven.
If you’re not sure which foil suits your setup best, get in touch with us. We’re always happy to help you choose what’s right for your projects.
Shop Heat Treating Foils
Looking to try the new grades? Check out the range below:
Shop 309 Stainless Heat Treating Foil
Shop 321 Stainless Heat Treating Foil
Both foils are available in multiple widths and lengths to suit your setup.
