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"Faraday Wax" - recreating old school high-vacuum epoxy!

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ChristofferB:
Hi! I've posted about this on some other forums but I thought you guys might be interested as well!

I'm doing a lot of high vacuum stuff, and this gets expensive fast, if one were to do things by the book. The standard high vacuum epoxy, Torr Seal (by Varian) is very expensive, and the generic high vacuum epoxy, Hysol 1C is not available in EU.

EDIT: I got around to making a quick video on how to use the wax for sealing purposes, I hope it's OK I attach it here:



Apparantly, in the olden days, a red wax was used to seal vacuum systems, make glass-to-metal seals etc. well into the 20th century. A famous example is Lawrence's first 4-inch cyclotron in 1930:


I found a recipe in a review from 1936 (L. Walden, J. sci. instrum. 13, 345) that describes "Faraday wax" - as first described by Michael Faraday in "Chemical Manipulation" from 1827.

By weight:

1 pt. yellow beeswax
5 pt. colophony (Rosin)
1 pt. Venetian red

Melt beeswax, add rosin gradually, add Venetian red and stir until uniform, stir while cooling. I poured mine into strips on baking paper to be touched to the preheated surfaces to be joined. Can also be applied with brush if used directly from the melting pot. Mine melted nicely around 130-140*C

I sealed a KF25 flange with a 10mm hole with a small brass plate, by first waxing the sealing surfaces and then pressing together after reheating.
Mounted on my turbo-pump vacuum system.

THIS 200 YEAR OLD NATURAL PRODUCT WENT DOWN TO 10^-7 mbar!

-No increase in pump-down time, ultimate vacuum or turbo pump load. I was stunned!

So yeah, this is well worth having a stick of around! Only downside is, it can't be heated. duh.

Gregg:
It looks a lot like old fashioned sealing wax that was commonly used to seal documents over a century ago.  It came in sticks that could be melted with a candle flame and dripped onto the closing flap of a document and a metal embossed unique seal form pressed onto the surface.  It was somewhat pliable but friable enough to clearly show any tampering.

ChristofferB:
It does, and it smells like it too, with the notable difference that it cannot be used as sealing wax! I tried, ended up with all of the wax stuck in the seal  :palm:

jpanhalt:

--- Quote from: ChristofferB on May 23, 2021, 10:23:56 pm ---
Apparantly, in the olden days, a red wax was used to seal vacuum systems, make glass-to-metal seals etc. well into the 20th century. A famous example is Lawrence's first 4-inch cyclotron in 1930:


--- End quote ---

Brings back memories.  In 1959, I made a linear accelerator with a Van de Graaff generator that was based on a Scientific American Amateur Scientist article.  Used the same recipe for my sealing wax, except I didn't add any coloring.  A very nice chemist/glassblower at CalTech gave me the diffusion pump.

YetAnotherTechie:

--- Quote from: ChristofferB on May 23, 2021, 10:23:56 pm ---
THIS 200 YEAR OLD NATURAL PRODUCT WENT DOWN TO 10^-7 mbar!

--- End quote ---
But how does it compare against plain-old epoxies??

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