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mkawa:
I want to expand on the ASME standard for pressure vessels. What this means in factual terms is that the welders involved in making the pressure vessel have ASME certification. The facility manufacturing the vessels must also have ISO and ASME certifications. Finally a comprehensive visual and usually x-ray inspection is performed for every finished unit. It is not a guarantee that the unit will not fail. However, it is about the best that we have available. Finally, The vast majority of of ASME certified vessels are made in the USA with traceable sources of steel. I emphasize this because steel and aluminum sourced from overseas is often very high in impurities. These impurities can lead to catastrophic failure despite a sound vessel design.

bcredbottle:
Does anyone have experience with surfactants to facilitate degassing (e.g. BJB AF-4 Anti-Foam)?

At least according to one documented anecdote, it can make a huge difference.

Strangely, I can't find much information about it apart from the post above. And I haven't found any examples of either (A) it being used on a small-scale cast (like a keycap); or (B) its application in gravity-casting.

With and without surfactant:
More

mkawa:
would not recommend. the mechanism of action is going to be something like a viscosity decreasing agent that will change the composition of your casting material. in complex multipart multi-rx materials, that could result in unpredictable cure schedules and worse, non-uniformity of cure (the whole point of thorough mixing..)

HoffmanMyster:

--- Quote from: mkawa on Tue, 03 November 2015, 22:09:47 ---would not recommend. the mechanism of action is going to be something like a viscosity decreasing agent that will change the composition of your casting material. in complex multipart multi-rx materials, that could result in unpredictable cure schedules and worse, non-uniformity of cure (the whole point of thorough mixing..)

--- End quote ---

Surfactants typically affect the surface energy of the substrate (which may have a slight effect on viscosity). The specific surfactant he listed seems to be designed for this application, so I don't see much harm in trying it. In fact, if I ever tried my hand at casting I was going to test some surfactants too.

Also, they are actually pretty common in industry (especially in inks, which yes, are resins in a lot of cases), though the application is indeed quite different.

Your concerns are certainly valid and something to be keeping an eye out for, but if you can't figure it out just revert back to he original recipe. No harm in trying.

mkawa:
Ah, ok. Good to know

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