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I am doing some mods to my still over the winter and require hard solder to put a few of the pieces together. I have searched high and low and all the rods I have found so far contain zinc, even the silver solder. There is roughly between 10% and 40% zinc in these solders and from what I have read on here, zinc is not still compatible. Does anybody know where I could get some of the food contact safe rods please? I only need about 10 rods or so. Thanks.

Zinc is OK, it's lead you want to avoid.

Zinc is not ok. Have a look on eBay or ask at your local welding supplies store.

Have a look on eBay or ask at your local welding supplies store

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I have done that and exhausted every other option I can think of including searching google, youtube and pretty much every distiller / homebrew forum on the net including this one. I wouldn't of asked if i hadn't already looked.

It worries me that people recommend using silver solder when all I can find here in the UK is the zinc laden stuff. How many people have built a still and not known?

Try these
http://www.ebay.co.uk/itm/WELDING-ROD-H ... 508733595?


NOMINAL CHEMICAL COMPOSITION:
Silver 4.8-5.2 %
Phosphorus 5.8-6.2%
Copper Balance
Other Totals 0.15 % maximum
PHYSICAL PROPERTIES:
Available forms
Solidus 1190°F (643°C) Electrical Conductivity 9.6
Liquidus 1494 -1506°F (812-819°C) Electrical Resistivity 18.1
Brazing Temperature Range 1320 - 1500°F (716 - 816°C) Specific Gravity 8.14

Sorry I should've been a bit more specific. I am going to be brazing some copper to stainless. From what I have read phosphorus and iron containing alloys don't work well together. Also I am really trying to get rods local to me because shipping from overseas is killer. Badbird, the rods you mentioned are £10.91 which is reasonable but the postage is £8.18! And that is for just five rods which weigh next to nothing.

The Harris safety silv range is rated for food processing but it contains zinc too.
Safety-Silv® 56
Description: High-silver Brazing Alloy
High silver content alloy; makes premium-quality brazes. Free-flowing with unsurpassed capillary attraction and deep penetration with high ductility.
Typical Application: Suitable for use in the food processing industry. Silver color is excellent match for stainless steel and silverware applications.

Composition:
Cu - 22%
Zn - 17%
Sn - 5%
Ag - 56%

This could be another case of "Food safe is not necessarily still safe"

Myself and lots of others have had good success soldering copper to stainless using Harris stay clean flux and Harris stay brite solder. The stay bright solder is 96% Sn and 4% Ag

Myself and lots of others have had good success soldering copper to stainless using Harris stay clean flux and Harris stay brite solder. The stay bright solder is 96% Sn and 4% Ag

I actually need hard solder to do some joints. One part of my still is a soldered part within a soldered part. I use hard solder for the inner part because of the high melting temperature and then use soft solder like stay bright to do the outer part because of it's much lower melting temperature. That way it all stays together.

If anyone is interested, I also figured out a way to use plain old plumbers solder to connect copper to stainless without loads of cleaning and fuss. Simply add a tiny amount of phosphoric acid to your plumbers flux, about two drops per teaspoon sized amount. I use 81% hydroponic grade phosphoric acid.

Liberally apply this flux to your stainless part and use a 300w soldering iron to tin the solder to the stainless. Don't let the iron get too hot because once this flux starts getting oxadised it will pit the soldering iron. Once stainless is tinned with solder wash the flux off thoroughly. You can then use a blowtorch and normal plumbers solder and flux to connect your parts as you would connecting copper to copper. I connected all of my SS tri clamps to my copper tube this way and they are still going strong after a year and many distillation runs later. Oh, and if anyone's worried about the hidden horrors of phosphoric acid it might be too late. Especially if you drink Coca~Cola, it's laced with the stuff.

Composition:
Cu - 22%
Zn - 17%
Sn - 5%
Ag - 56%

This could be another case of "Food safe is not necessarily still safe"

Looks OK to me at least there's no cadmium.
If you are uncomfortable with the zinc and soft solder wont work, getting someone to tig it for you is probably the only option.
Brazing stainless usually makes a mess anyway.

Looks OK to me at least there's no cadmium.
If you are uncomfortable with the zinc and soft solder wont work, getting someone to tig it for you is probably the only option.
Brazing stainless usually makes a mess anyway.

It is not just cadmium that is a problem. Some rods contain antimony which can be very poisonous too.
Tig was my first option but I know nobody who can do it and I could pretty much make another still for the amount it costs to hire a tig welder for just one day.
Messy stainless isn't a problem. If it works right and is safe, does it really matter what it looks like?

Ok. Its hard to argue that there is any place for Antimony, Cadmium and Lead in what we are doing but zinc as part of an alloy? I can understand avoiding solid or plated zinc but a lot of members seam comfortable using small amounts of lead free brass which as has been pointed out, still contains a very small amount of lead.

The Harris safety silv 56 its essentially 50% fully lead free brass and %50 silver, haven't used it personally as I'm a soft solder fan where stainless is concerned but the silv56 sounds like nice stuff to use.

Ok. Its hard to argue that there is any place for Antimony, Cadmium and Lead in what we are doing but zinc as part of an alloy? I can understand avoiding solid or plated zinc but a lot of members seam comfortable using small amounts of lead free brass which as has been pointed out, still contains a very small amount of lead.

It depends where in the world you are as to how much lead is in lead free brass. In the States for instance the allowable amount has been reduced from 8% to 0.25% since January of this year. Even that reduction is not enough IMO because there is no safe lead level. Another thing about brass is that one of its major constituents is zinc (about 33%) and that in certain moist conditions it is prone to dezincification. Zinc it is still bad for you whether it is part of an alloy or not.

Anyway, if anyone does know of a "still safe" brazing rod that does not contain zinc and is available in the uk please chime in. If you think I am being over cautious or my fears are baseless please chime in too.

Not to bump this but I did some research, a little experimentation and thought it would be a good idea to share.
Zinc is food safe in an alloy as Badbird said but is a health hazard on its own ie zinc plating.

For copper to copper brazing I used these rods: http://www.ebay.co.uk/itm/191368567796? ... EBIDX%3AIT
They are a no brainer and don't require flux when soldering copper to copper. When soldering copper to brass you need flux. You can't use them with ferrous metals because they cause "brittle intermetallic compounds".

For stainless to copper I used these rods: http://www.ebay.co.uk/itm/Silver-Solder ... 27f7bac618
I recommend these as the absolute minimum silver content rods (40%) when using mapp gas. You will struggle like hell to get the rod to flow on larger pieces with less silver in them.
When you are a clumsy brazing novice like me you will find it difficult not to overheat the piece you are working on. If it is stainless, the flux will become exhausted quite quickly and the rod will struggle to flow.
Flux coated rods make a huge difference because you are constantly laying fresh flux into the joint which pretty much ensures a smooth join every time.

I know the above is probably common knowledge but it could be useful to someone someday.

go to a plumbing shop the stuff they use for copper pipes is safe