I am in need of producing some small investment-cast yellow brass parts for small scale models. I have been told that casting yellow brass is prohibited at DMS due to hazmat issues?
Is this an internal DMS policy or EPA or local government restriction? If this is an internal policy, then it should be reviewed…after all, 60/40 solder used by electronics…not to mention the welding and stained glass labs! 
This is an internal committee policy that was established when we first got casting equipment several years ago. We also do not permit the casting of pewter for the same health concerns. I don’t know if local restrictions or EPA have had anything to say about it.
I can’t speak to the other committees, but I for one will fight against any attempts to change this jewelry committee policy.
Bronze casting is permitted.
Then I would suggest that you fight to close down both the Welding and Electronics Labs and Committees for the same reason…after all, 60/40 will kill you!
The issue here is Zinc (Zn) fumes, correct? Not lead (Pb). Brass is 1/3 Zn roughly - the rest being Copper (Cu). And 60/40 solder is the ratio of Tin (Sn) to Pb - not Zn related.
FWIW, the last time I checked, Metal shop does NOT allow welding of galvanized metal due to the Zn fumes. (https://dallasmakerspace.org/w/images/f/fa/Metal_Shop_Safety_for_Hot_Processes.pdf – page 11)
OK. I was previously told that the restriction was due to lead content.
What bronze alloys are permitted? Need a alloy with a very fine grain structure and 60/40 solderability to produce very small model parts with excellent detail and that can be painted. Any recommendations?
Non-Zinc alloys.
Disclaimer: I have minimal knowledge of specific alloy properties.
That said, it is my understanding that bronze doesn’t like to be soldered. I’m not sure if we’ve got anybody who understands all the nuances of bronze alloys. I mean, photomancer (David) didn’t expound.
And, @darrent, you are correct. Metal Shop still doesn’t allow any welding of zinc anything.
I know there are different types and they vary by alloying metals for different applications. Mainly familiar with silicone bronzes as they are used in marine applications - which are usually cast then machined. As far welding or soldering - not familiar with them. I would suspect if solderable it would be with silver solder as it creates strong joints, but that also depends on various fluxes that can be used.
I quick look online shows everything from 50%-100% silver solder but people have problems at times with blackening and oxidation.
Yes the zinc content is the initial issue we have with casting brass. The yellow brass casting alloys I found also have 1% lead which I wasn’t even aware of until now!
Bronze is what we used for all of my school projects and this involved a lot of soldering on it, it was silicon bronze
Do you remember the type of solder? Assume Silver, but what percentage and also the type of flux? This would be helpful to those attempting it? Any brazing for even stronger joints? As I’ve said, my experience has been with solid castings that were machined.
We used gold solder because it’s not as visible 14k i think, 10k sucks to work with. I’m not sure how silver solder would behave with it.
Flux ws borax paste, and soldering fine jewlery is really what a welder would consider low temperature brazing, I don’t know why we refer to it as soldering.
Here, for clarify when I refer to soldering, this technique is what i am referring to, torch soldering, not using a soldering iron. I always forget most people think of soldering as the techniques used in stained glass and electronics!
When I think of soldering/brazing as the material used to join the metal. In aerospace we did a lot of brazing on tubing and such, almost always done with paste in vacuum furnace or sometimes in controlled atmosphere - usually mounted on fixtures.
The types of electrical soldering for circuit boards was either reflow ovens (surface mount) or weirs (though board, which is cool to watch). Terminals on wires or terminations of wires on to something were usually hand soldered. In HS did some soldering on sheet metal projects, similar to what @Mrholthaus teaches sans soldering, using massive soldering irons put in a furnace.
Lots of different ways
In personal use, probably the most common soldering I’ve done is copper piping “Sweating Joints” together. First time I personally used silver solder was at DMS and some foil soldering in a stained glass class.
Soldering vs brazing is, I think a matter of historical usage more than definition. Though I tend to think of soldering as filler that could successfully be applied with propane air torches. Things that require at minimum Acetylene air or MAPP air seem to be on the fence, soldering or brazing depending on the particular trade. And things that require oxygen are pretty much always brazing, until you start melting the base metal.
Don’t get me started on the trade with a certain subset that seems to think that just because you are using the smallest refillable O/A bottles, what you are doing is welding. Let me see you melt that copper and use an extremely high copper alloy, or pure copper filler, then you will get my respect for your welding skills. But you most likely won’t be doing that on 3/4 copper pipe with that setup.
I will also note that country and language seems to make a difference. Chinese soldering (normal 60/40 or lead free) seems to always translate to welding when translated to English.
I know that you can get some pretty fine detail with aluminium casting
Jewelry also has the Hydro-flux torch. We used a soldering/brazing technique, as we didn’t melt the silver. Although – I think we could have. I remember that Ann said she’d just melted her earwires trying to solder them.
One wonders if you could call it brazing if you’re not using brass…
Chinese may not differentiate between welding (base metal is melted) and soldering/brazing (only the attaching metal is melted).
Soldering vs brazing is a matter of the temp difference. Anything below 840 degrees f is considered soldering. Above that 840 mark is brazing. I’m my trade we still call it silver soldering even though it’s brazing. My guess is to why we use this misnomer is because 45% or ever 56% silver filler comes usually in rolled up form.
As to brass, there are so many variants. Some have lead, some do not.