¶ Hard Soldering
In what ways and who/when hard soldering is allowed is still in conversation!
¶ Current state
The current concerns I (ronja) as the jewelry curator have heard are the following:
- ventilation:
- propane with a proper burner burns very cleanly
- hard soldering at around 730°C uses fractions of grams of material and uses alloys that do not produce dangerous fumes or particles
- pickling with jewelers pickle (acid bath at around 50-60°C) has some minor off-gassing, but is not generally considered dangerous, we can set up a local filter.
- melting small amounts of silver or bronze is safe and does not produce hazardous fumes or particles
- melting larger amounts of material isnt viable with the initial blowtorch setup anyways
- melting brass or other zinc alloys with melting points >900° do produce hazardous particles and will be forbidden
- (permission for smelting alloys will be given on a case-by-case basis with proper research, similar to lasercutter material list)
- fire safety:
- the table to solder on will be fire-proofed
- we will buy a gas alarm that warns in case of leaking gas
- hard-soldering will only be allowed with an extensive introduction and if people dont seem trustworthy during the introduction they will not be allowed to use hard-soldering
- the idea was brought up to get an igniter to make restarting the flame more effortless and disabling it when not actively in use: https://www.zujeddeloh.de/produkte/werkzeuge_+_zubehoer/loeten_und_schweissen/brenner_und_zubehoer_--216/automatischer_gasanzuender--_8509.html
- I suggest we have a small amount of trusted people who will be allowed to open the propane tank and who's responsibility it is to close it before they leave, never having the main valve be open without supervision.
All these ideas of mitigating dangers have been talked through with my goldsmithing teacher who has many years of learning, doing and teaching goldsmithing.
¶ Intermedia state suggestion
There was talk about using smaller handheld blow-torches for getting goldsmithing with hard soldering off the ground as these have smaller tanks and as such can't leak as much gas. If people require proof for the cleanness in terms of air quality, these can also be used to test-run that and collect data with air quality monitors.
If we go with the suggestion of having a small amount of "fire keepers" they could also function as back-up when none of them is around to be responsible for opening the tank.