Natriumperoxidisulfate not working on alu?

[Ge_Whiz]

Etching aluminium with sodium peroxydisulphate is not going to release any copper, as there isn't any present. Anything used to etch copper will end up containing copper by definition. Incidentally, a meal consisting mainly of prawns or shrimps will take you over the industrial exposure limit for copper ingestion for at least 24 hours. Don't blame the Europeans - sodium peroxydisulphate is less hazardous than iron (III) chloride or sodium hydroxide, although in all cases it does, of course, depend on the concentration used.

If you want to colour aluminium boxes, research 'anodising'. Aluminium can be anodised to the oxide fairly easily, after the top layer has been chemically stripped, and you can add pigments to colour the oxide permanently.

[Paul Perry (Frostwave)]

Incidentally, a meal consisting mainly of prawns or shrimps will take you over the industrial exposure limit for copper ingestion for at least 24 hours.

Interestingly enough:
" ...crustaceans, such as shrimp, lobster and crab, are in particularly need of copper because its serves as an oxygen carrier in their blood.
Dr. Lewis, the University of British Columbia oceanographer, notes that "copper concentrations in crustaceans may be elevated compared with other groups since many crustaceans use copper in a blood pigment..."
That is why, if you look closely, blood on an uncooked shrimp looks bluish, a typical color of certain forms of oxidized copper. Copper in marine invertebrates plays the role that among humans is performed by iron, which is present in blood as hemoglobin. "

[WildMountain]

What were the results of this etching project? Any pics? Did you get the $uperpuma skull-effect?

[JimRayden]

Well, after being scared off by this thread, I used water at room temperature and didn't get anything but grayish staining on the surface. Trying to warm up the action and not having a warming device at hand (and not wanting to dissolve it too much with hot water), I placed the box into the etchant and poured steaming water into the aluminum box itself. It heated the box and things were looking up. But soon I had to go since I had been playing around for about an hour or so.

The result wasn't as extreme as I'd expected but it did etch quite a bit. Next time I'll go to my neighbour's kitchen because he has that ventilation system over his stove, so I can keep things warm and ventilated.

Pictures coming right up.

---------
Jimbo

[markm]

Great news Jim!
I'm eager to take a peak.
Post 'em soon.

[JimRayden]

There is some bevel visible under certain light conditions but generally the difference between etched and non-etched surface is the amount of reflection. One can also feel the image by sliding over it with a finger.

http://www.stockdork.com/playout/sodiumhydroxiderocks/waggew.JPG

I'm gonna go for another try in a week or so. This time it'll be a BB. And hot.

[edit] Just for a note, there was nothing wrong with the transfer, it was intended to be blotchy.

---------
Jimbo

[markm]

you guys can't get Ferric Chloride across the pond huh?

[JimRayden]

Doesn't seem like we do... Banzai only has the natrium/sodium sulfate thing and ELFA has this plus NaOH.

I'm sure next time will be more successful with the NaOH.

----------
Jimbo

[gez]

Jim, every UK supplier I know sells Ferric.  Example (you can buy it in smaller quantities and cheaper):

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M61309&XPAGENO=1


Edit: This is how I normally buy it:

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M72531&XPAGENO=1

[JimRayden]

Thanks, I'll look around for that stuff. I'm lazy and only visit only that one electronics store in town. I'll have to go on a ferric-trip out of town.

---------
Jimbo

[JimRayden]

Whaddaya see, Jimbo just found an 'alternate' internet store around here that sells ferric. Oh joy, I won't even have to get off my lazy arse. That stuff is much cheaper than NaOH, by the way.

Second etch-raport to be posted. This time with ferric.

---------
Jimbo

[markm]

That should work much better.
What brand enclosure do you have??
I just etched an Eddystone and it etched REAL quick with Ferric.
Generated a bit more heat than the Taiwan made jobs too.
It was quick but I ended up having to rinse four times during the etch.
Strange.

[JimRayden]

This one was a Taiwanese 125B which I love because of the PCB-ribs and their depth. Next one to etch is a Hammond BB.

---------
Jimbo

[WildMountain]

I have the same problem getting my hands on some ferric chloride. I use sodiumperchlorate for my pcb's. Do you have any experience etching boxes with that stuff and pnp?

[Paul Perry (Frostwave)]

I havn't tried it, but I'm certain that hydrochloric acid (sold at hardware stores as Spirits of Salts sometimes) will etch aluminium or zinc boxes. Do it outside, hydrochloric acid fumes are irritating.