Replies to This Discussion

Permalink Reply by JUJU on March 5, 2011 at 11:35am

i have heard bleach works - the method > place the Brass part on supports in a plastic bag ,  tub or whatever needs to be able to seal it to a degree the bleach goes in the bottom of the Plastic bag, or tub and the supports stop the Brass part from touching the actual bleach supposidly it's the fumes from the bleach that do the work thats why you need to be able to seal the Bag or container i have not tried this myself as yet it's something i was told the other day if i had known before i assembled the tricone build i would have tried it myself

hope that helps and hope it works keep me posted if you would

juju :)

Permalink Reply by JUJU on March 5, 2011 at 11:36am

PS it takes 12 hrs ish ! and make sure the part has no fingerprints on before hand

Permalink Reply by Roadkill a.k.a. John Maw on March 5, 2011 at 11:42am

Hi Juju and thanks for the quick response. Sounds like chlorine gas is the idea - I think that's what bleach gives off. I will try it tonight. Although I have more work to do on it (and therefore more filing and papering), at least I will know if it works, and yes, I will report back. Thanks again.

Permalink Reply by Wes "I'm Baaaaack" Yates on March 5, 2011 at 11:52am

Salt? Soak and see if that will make a patina. Heat and dip in a salt solution

-WY

Permalink Reply by JUJU on March 5, 2011 at 12:35pm

also viniger and salt mixed works on copper so it will work on brass as there pretty much the same - Method Malt vinegar (sarsons) heat up in a pan add a good dose of table salt and desolveit in the hot vinegar  leave to cool - i used a plant sprayer to apply it to the copper gave it a light coat every half hour for about two hours then left it overnight - washed the copped down in soapy water and it was tarnished

heres the copper plate i did this was brand new copper before hand

Permalink Reply by Roadkill a.k.a. John Maw on March 5, 2011 at 1:18pm

Thanks Wes and Juju.

I have the brass in a sealed food container with something to keep it off the bottom and some bleach. Will see how that does and then try the salt and vinegar treatment tomorrow (Couldn't just blast it with salt and vinegar crisps under pressure could I? Maybe that's where they got the idea for the crisps.) That pic of the copper plate and the pickups looks terrific.

Thanks to both of you for the help.

Permalink Reply by Wiley Rutledge on March 5, 2011 at 2:33pm

I THINK most methods that use acids or chlorine beach will take at least a few hours or maybe a couple of days.  I used to polish brass for band uniforms and the worst tarnish was usually after hot, sweaty competitions especially when it was humid or rainy.  I think the salt involved and the small amount of ammonia in the sweat was the acting agent, and I've seen heavy tarnish on Monday after a Saturday band trip.  The old backwoods gun makers, when the raw steel of the barrels were usually browned instead of blued would stand the barrel in a corner of a fence and urinate on them as well as let them weather, then sand lightly and oil heavily for the finish.  The ammonia and salt in the urine seems to have been a heavy rusting agent, and I think when polished brass wasn't wanted on a service weapon they used the same methods.  The acid/salt of the vinegar should work if the bleach doesn't, but don't expect it to happen before your eyes.  (Or carry them with you to a heavy workout and leave them in your sweats for a couple days and see what happens. :>) ).

Good luck.

Permalink Reply by Shawn on March 5, 2011 at 5:26pm

I have used a mix of miracle grow plant food and water made into a paste and let it sit for a few hour gave it a greenish brown look. Then I heated it up to get the the dark look of old brass just right. I think the ph in the miracle grow etches it as it was not smooth anymore.

Permalink Reply by Wes "I'm Baaaaack" Yates on March 5, 2011 at 5:27pm

Silly, but i think Wiley had so ething there -- urine. No joke. I know folks soak dyed material inurine to set the colors and urine has urea, sodium, chlorine and potassium. I bet that would work tho it could stink.

-WY

Permalink Reply by Jarmo Katajisto on March 5, 2011 at 11:39pm

Hydrochloric acid perhaps?

 

I read in Wikipedia at everybody find that own stomach but it might be difficult use it in your problem, maybe you find that in pharmacy.

Permalink Reply by Roadkill a.k.a. John Maw on March 6, 2011 at 6:04am

Wow. Thanks Wiley, Shawn, Wes and Jamo.

Some really interesting suggestions. So far the bleach and the salt + vinegar combination have left it largely untouched. I did get a little pink colour around the edges when combining the salt/vinegar with heat from a soldering torch but even then only slight. I have done a bit more digging elsewhere and it seems as though brass comes in many forms (alloy combinations I suppose) and with different properties. I don't know what it is so it's difficult to predict.

 

I found some other recommendations but they all involve chemicals that may be hard to get. I will ring the pharmacist tomorrow and see if it is possible to obtain any of them. Just in case anyone is interested here is the list.

 

1pt copper sulphate to 2 parts water

 

barium sulphide (hot)

 

Ammonium sulphide 1gm

Water 7oz

 

Potassium sulphide 1gm

Water 7oz

 

Copper nitrate 1gm

Ammonium Chloride 1gm

Calcium chloride 1gm

Water 20gm

 

Phosphoric acid (no quantities given)

 

I was no good at chemistry at school but some of this sounds as if it might be hazardous. My problem is also that I would prefer to get the bridge on pretty soon so I really need something that works in a few hours (at most) rather than a few days. If all else fails it will have to go on as is and acquire it's ageing in the natural way.

 

Again, thanks to all for the help. Out of interest here is a pic of the piece in question.

 

Permalink Reply by Murray on March 6, 2011 at 8:27am

I think the green patina on copper & bronze is poisonous. It obviously occurs on copper flashing & gutters & statues, but they aren't normally handled.

 

This is probably no better, but if anyone has old photography chemicals from dormant darkrooms, selenium toner for b/w print paper will make copper a dull dark gray pretty quickly (minutes at most). I don't know it's health risk rating at that  point. I batted that around with some people on a photo forum once & we couldn't be sure what compound was formed on the surface or if it was stable. Sulfides & selenides were suspected. Either one based on copper might be a crude semiconductor.

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