An unusual electrolysis help request.

[boguing]

I need to produce some Copper 'looking' screws. Which I can't find at short notice.

So, I want to de-zincify some Brass ones.

Any suggestions for:-

Brass is +ve or -ve?

Anything special needed for the other electrode?

Using distilled water, is there anything I can add to boost the process?

Finally, what would the ideal voltage be.

If anybody wants the Zinc thus produced, to add back to your tired prop, you're welcome.

 

[VicS]

Not sure that's the way to do it.
To do what you suggest just sitting in some acid ( dilute sulphuric) might do the trick.

To do it by electrolysis you need an electrolyte, not just distilled water. Dil sulphuric acid would do nicely, presumably even salt water would do . You would connect the item to be treated to the positive. IE make it an anode.

Almost anything that conducts but not attacked by the electrolyte would do as the other electrode. Carbon rod would be a good choice .

BUT
IMHO the better method by far would be to plate out some copper onto the surface.

But you would need some copper sulphate to make the plating solution and to get a decent adherent deposit you would probably have to do it from an ammoniacal solution at the very least. Commercially a cyanide bath is used.

 

[Vara]

Even vinegar would have some action, the hotter the better.

 

[AntarcticPilot]

I'm sure you could devise some electrolytic cell to do what you want. But the result will have negligible strength; probably not enough to screw them into anything.

Also, the result won't be a polished copper surface; it will be a powdery red colour.

How about creating a plaster mould of a screw and then casting one? Copper melts easily enough at "domestic" temperatures - a blow torch should do it.

 

[Stork_III]

I need to produce some Copper 'looking' screws. Which I can't find at short notice.

So, I want to de-zincify some Brass ones.

Any suggestions for:-

Brass is +ve or -ve?

Anything special needed for the other electrode?

Using distilled water, is there anything I can add to boost the process?

Finally, what would the ideal voltage be.

If anybody wants the Zinc thus produced, to add back to your tired prop, you're welcome.

You could use some of these or similar? http://www.drainageonline.co.uk/ancillary-items/35mm-copper-screws.htm

 

[boguing]

Great advice thanks folks.

Firstly, the screws are decorative, being used by cost centre #1 for a design project, so strength is not relevant.

Appearance is, however, and anybody that will make them was way too expensive.

Casting them was today's plan, but my torch only gets it bright orange. I can't think of anybody among local friends who has oxy/acet. Tomorrow is Sunday so nowhere commercial open, and she needs them on Monday.

Another thought was to drill steel and hammer red hot copper into it to form a 'rivet' that looks like a screw. Problem is that I've only got sheet or thin wire and nothing to make the nuts from (easily).

So bought brass screws, washers and nuts.

Vic. I have conc. Sulphuric. What %age with dist water would you guess at?

Carbon Rod. CC #2 is just checking the house for dead alkaline batteries...... yes, we have 4 D cells. Will the rods from these work?

So, looks like I've got the basics. I have 3Amp DC supply at 20V. Too much?

 

[VicS]

Great advice thanks folks.

Firstly, the screws are decorative, being used by cost centre #1 for a design project, so strength is not relevant.

Appearance is, however, and anybody that will make them was way too expensive.

Casting them was today's plan, but my torch only gets it bright orange. I can't think of anybody among local friends who has oxy/acet. Tomorrow is Sunday so nowhere commercial open, and she needs them on Monday.

Another thought was to drill steel and hammer red hot copper into it to form a 'rivet' that looks like a screw. Problem is that I've only got sheet or thin wire and nothing to make the nuts from (easily).

So bought brass screws, washers and nuts.

Vic. I have conc. Sulphuric. What %age with dist water would you guess at?

Carbon Rod. CC #2 is just checking the house for dead alkaline batteries...... yes, we have 4 D cells. Will the rods from these work?

So, looks like I've got the basics. I have 3Amp DC supply at 20V. Too much?

Sulphuric acid ?????? 2% by volume perhaps down in that region I would think 5% maybe( dont forget add acid to the water!!)

Dont worry about the carbon if not to hand use a piece of copper.

I'd think 20 volts will be too high 6 volts may do.

No real feel for what you are doing. I'd be happier plating. Electroplating is a documented method of quantitative analysis for copper. I have used the method ... many years ago. Get the conditions right and you get a nice bright adherent layer of copper deposited ( on a platinum cathode )

 

[AntarcticPilot]

Great advice thanks folks.

Firstly, the screws are decorative, being used by cost centre #1 for a design project, so strength is not relevant.

Appearance is, however, and anybody that will make them was way too expensive.

Casting them was today's plan, but my torch only gets it bright orange. I can't think of anybody among local friends who has oxy/acet. Tomorrow is Sunday so nowhere commercial open, and she needs them on Monday.

Another thought was to drill steel and hammer red hot copper into it to form a 'rivet' that looks like a screw. Problem is that I've only got sheet or thin wire and nothing to make the nuts from (easily).

So bought brass screws, washers and nuts.

Vic. I have conc. Sulphuric. What %age with dist water would you guess at?

Carbon Rod. CC #2 is just checking the house for dead alkaline batteries...... yes, we have 4 D cells. Will the rods from these work?

So, looks like I've got the basics. I have 3Amp DC supply at 20V. Too much?

A Meker Burner (http://en.wikipedia.org/wiki/Meker-Fisher_burner) would do it.

 

[boguing]

Not that many of those available at this tome on a Saturday..

 

[Maurice55]

I aggree with VicS, electro-copper plating them has got to be the easiest way round it.

 

[alant]

I need to produce some Copper 'looking' screws. Which I can't find at short notice.

So, I want to de-zincify some Brass ones.

Any suggestions for:-

Brass is +ve or -ve?

Anything special needed for the other electrode?

Using distilled water, is there anything I can add to boost the process?

Finally, what would the ideal voltage be.

If anybody wants the Zinc thus produced, to add back to your tired prop, you're welcome.

Spray them!

 

[VicS]

Spray them!

Copper coloured Hammerite ??

 

[alant]

Copper coloured Hammerite ??

No, find a hobby shop or similar, selling gold/silver/copper/etc sprays for decoration.

 

[boguing]

Snag is that this is my daughter, who seems to have inherited the questioning gene from her aged pa.

She went off around Europe last Summer and came back in love with 'patinated' (or knackered) Copper rooves.

This project requires that patination.

Can't get Copper Sulphate over the weekend, otherwise would have gone for that.

Leaching out the Zinc is the only option. For now.

We are better prepared for next time, and will be equiped to melt or Cu plate for then.

Will let you all know how the process goes tomorrow.

 

[alant]

Snag is that this is my daughter, who seems to have inherited the questioning gene from her aged pa.

She went off around Europe last Summer and came back in love with 'patinated' (or knackered) Copper rooves.

This project requires that patination.

Can't get Copper Sulphate over the weekend, otherwise would have gone for that.

Leaching out the Zinc is the only option. For now.

We are better prepared for next time, and will be equiped to melt or Cu plate for then.

Will let you all know how the process goes tomorrow.

knacker first, then spray!

 

[SHUG]

Why not get nice bronze ones from:
http://www.gtc-direct.com

 

[geoffatstanpit]

Your local boatyard probably has copper rivets for mending clinker boats (if they can remember them!). You could cut threads in them with a die and a slot in the top with a hacksaw.

 

[boguing]

Thanks to Vic, and others who appreciated that this was a must do now project.

Two goes later, I have a complete set of (surface) de-zincified brass screws, nuts and washers.

Two goes?

Well. The washers were a bit slower to react. Due to either:- possibly being lacquered, and/or stamped from sheeet and so more homogenous than the (probably) cast with a little forging, screws and nuts.

Left them all in too long, so the Cu started to disappear from the screws and nuts. Back to Brass. Booger.

Second time, screws, nuts and washers all done separately. Pink everything.

What is absolutely terrifying though, is that on the first run it took 10 minutes at 5% Sulphuric, 5 Volts and 0.6 Amps to do the screws initially.

Second time was 'cleaning up' and about about a minute for each.

Seawater may not be as good an electrolyte as mine, but the YM article that I read recently about a stray current and very quick disintegration of a skin fitting beacame rapidly more believable.

Will put some pics up once CC#1 has completed the project.

ps. If Mr Robson is reading this, you may actually not have been the worst Chemistry teacher that I ever had. Loved all the hot stuff experiments that went spectacularly wrong though.

pps. Mr Jones. You have no mitigation. Apathetic, I think you said. Not this week.

 

[VicS]

Thanks to Vic, and others who appreciated that this was a must do now project.

Two goes later, I have a complete set of (surface) de-zincified brass screws, nuts and washers.

Two goes?

Well. The washers were a bit slower to react. Due to either:- possibly being lacquered, and/or stamped from sheeet and so more homogenous than the (probably) cast with a little forging, screws and nuts.

Left them all in too long, so the Cu started to disappear from the screws and nuts. Back to Brass. Booger.

Second time, screws, nuts and washers all done separately. Pink everything.

What is absolutely terrifying though, is that on the first run it took 10 minutes at 5% Sulphuric, 5 Volts and 0.6 Amps to do the screws initially.

Second time was 'cleaning up' and about about a minute for each.

Seawater may not be as good an electrolyte as mine, but the YM article that I read recently about a stray current and very quick disintegration of a skin fitting beacame rapidly more believable.

Will put some pics up once CC#1 has completed the project.

ps. If Mr Robson is reading this, you may actually not have been the worst Chemistry teacher that I ever had. Loved all the hot stuff experiments that went spectacularly wrong though.

pps. Mr Jones. You have no mitigation. Apathetic, I think you said. Not this week.

Glad to hear it worked. Washers may have been a different alloy. Brasses tend to fall into one or other of two groups with different structures depending on the % zinc.