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This is a question Home Science

Have you split the atom in your kitchen? Made your own fireworks? Fired a bacon rocket through your window?
We love home science experiments - tell us about your best, preferably with instructions.

Extra points for lost eyebrows / nasal hair / limbs

(, Thu 9 Aug 2012, 17:25)
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Home Etching Device
Being into electronics when I was younger, I decided early on that standing next to a tray of etching fluid with a PCB in it just so I could tip it back and forth for 20 minutes was boring as hell.

So I set about thinking up designs for an etching machine.

After several attempts to build a motorised tray agitator from lego (I still have Technic lego with orange stains on to this day), my attention turned towards bubble etching.

Not having a suitable thin tank to place the pcb in, I found the biggest glass jar I could (Nutrasweet jar I think).

Now, the bubbles would be provided by a 12V car screen washer pump and some plastic tubing from Halfords. All I needed was a basket to put the pcb in and lower into the jar full of etching fluid.

Whilst at Halfords, I noticed a pack of aluminium mesh, the type used for car bodywork repairs. Purchased, and off home to sculpt a basket. After hours of careful cutting, folder and stitching together, the basket was ready.

The time came to try out the Mark II etching machine. Parents out that evening, PCB laid out with transfers, into the basket and etching fluid at the ready. I lowered the basket into the jar full of etchant, closed the lid and turned on the pump.

WOW! Look at all the etchant fizzing up - it's working great.

Hang on, the fizz is up to the lid, what happens if it keeps going?

Simple, the pressure build up causes the etchant to force its way through any channel it can find around the lid, out over the table top and start pooling up! Shit! Mop it up, mop it up. Why won't it stop?? Bollox, how do I get this out of the house?

I disconncted the tubing, dumped the smoking/fizzing bottle of brown acid onto a tray, covered it in newspaper, ran outside and dumped it in an inconspicuous area of the garden.

The cleanup job was hard enough, the smell quickly removed by opening doors and windows, and on the parents' return they knew nothing.

Next day, I awoke to the sound of my dad in the garden...bollox! Later on, he asked if I knew what the hell the glass jar of brown sludge in the garden was. I explained it was a PCB I was etching, but left out a lot of the detail!

On closer examination, the aluminium basket had completely etched away - all that was left inside was my PCB, perfectly etched.

So now I know, etching fluid isn't just for copper - it's also for 14yo kids to mix with raw aluminium in a sealed jar for potential explosive fun.
(, Wed 15 Aug 2012, 12:30, Reply)

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