Grow Your Own Guitar Pedal Finish, Chapter 2

[EBK]

The Chia Pedal was so much fun to make (see https://www.diystompboxes.com/smfforum/index.php?topic=121795.msg1150271#msg1150271)
that I decided to grow something else on an enclosure: alum crystals!

I'm stealing my own idea here, which should be ok, right?  Other people are still free to steal it from me too. 
https://www.diystompboxes.com/smfforum/index.php?topic=121960.msg1168394#msg1168394

I have received my alum today. Alum is basically a home industrial chemical that is useful in making leather, dyed wool, paper, and pickled vegetables.  It can also be used as a styptic to stop minor wounds from bleeding.  Very versatile stuff (there are more applications than what I've listed)!



Note, this is the potassium kind, specifically KAl(SO₄)₂·12H₂O (aluminum potassium sulfate dodecahydrate).
The word "alum" describes a family of aluminum sulfate salts, and there are definitely some that will not grow crystals in a home-kitchen-laboratory/science-fair-project setting.

To get a sense of what I'm planning, you can Google "homemade geodes", which is a craft project involving growing alum crystals on the inside of egg shells.

Edit:  Here is a great description of how to grow alum crystals: https://m.wikihow.com/Grow-Alum-Crystals

Stay tuned!

[Kevin Mitchell]

Neato! Can't wait to see how it develops 



I think you know where I'm going with this.

-KM

[Kipper4]

Intresting.....

[Axldeziak]

Way back in highschool chemistry we grew alum crystals. Had the luck of growing one over a half inch in size (largest in the class history.) It looked like a triangular lozenge with a triangle shaped divet in the center.
I was able to save mine for over 20 years in a small mason jar keeping it submerged in pure grain alcohol. Then one day, it just melted. I had added fresh to the jar every few years or so but forgot to that last time.
I had a chance to talk to the old chemistry teacher and she was amazed as she had never had a student keep one for even a year. She thought it may have had something to do with the fact I really overdid it when it came to dissolving the foil into the solution. (I kept adding it until the acid played out and couldn't dissolve any more.) Also, keeping oxygen from it using the pure alcohol helped as well. She even mentioned kerosene to store it as it would be less likely to take up oxygen from humidity in the air.
On a pedal? You'll have to seal it top and bottom really well. Also keep in mind they tend to be rather fragile. They aren't like natural aluminum crystals like emeralds, sapphires, ect.

[ElectricDruid]

I like the idea of emerald/sapphire encrusted pedals. How do I grow those?!?

T.

[Axldeziak]

The capability to maintain 1200+ degrees Fahrenheit at 10,000+psi for several weeks in an acidic solution of chromium and other pleasantries..

[EBK]

On a pedal? You'll have to seal it top and bottom really well.

But, with what is the question.  Water-based sealants are obviously out.  Rattle can clear coat?  Maybe worth experimenting with.  I've read that CA glue will stick to alum crystals.  Lots to think about and lots to try.  Even failure is a result, so I will forge ahead.   

[bluebunny]

I'm sitting back waiting to see how this pans out.  You're a crazy, crazy man, Eric, but that's what we love about you!    And you can use your creations as Christmas tree decorations too! 

[EBK]

And you can use your creations as Christmas tree decorations too! 

You mean like the salt dough covered Yule Screamer I just now dreamed up?   

[bluebunny]

And you can use your creations as Christmas tree decorations too! 

You mean like the salt dough covered Yule Screamer I just now dreamed up? 

Of course. 

I'm suddenly starting to renew my long-absent love of Christmas.   

[EBK]

I'm suddenly starting to renew my long-absent love of Christmas.   

The phrase "humbugger pickup" just flew into my mind.  I don't have a vision of what to do with it though.
Edit: Never mind. It exists.   

[Fancy Lime]

I like the idea of emerald/sapphire encrusted pedals. How do I grow those?!?

T.

Emerald is a bit tricky. The method is called "Chatham process" or "flux method". Put a generous helping of silicon dioxide (SiO₂) in a crucible and add a flux that lowers the melting point. Boron oxide (B₂O₃) and/or sodium fluoride (NaF) would be obvious choices. I don't have the phase diagrams at hand just now but those should get your melting point down to around 600°C. Heat the crucible to about 50°C above the melting temperature. Add beryllium oxide (BeO) and aluminium oxide (Al₂O₃) in approximately equal amounts. Add a pinch of chromium oxide (Cr₂O₃) for that nice green color. Drop in a seed crystal (a bit or emerald you happen to have sitting around in a drawer) and slowly, very slowly cool your mixture.
That's just the main outline, but should be enough to start figuring out what needs to be refined along the way. There is of course also the hydrothermal method, but that's not as easy to do at home unless you have access to a good machine shop that has experience with high pressure (10 kbar should be sufficient) equipment.

Sapphire is easy. It's called the Verneuil process and is basically just a blowtorch going to at least 2000°C with a feeding mechanism for the Al₂O₃-TiO₂-FeO mixture on the backside. That's absolutely doable for the intrepid hobbyist with a fireproof garden shed. Using the Czochralski process instead would potentially give you bigger, nicer crystals but is much harder to diy. However, if you are using an aluminium enclosure, it is covered in a thin film of sapphire, or more precisely corundum, anyway. Sapphire is just the name for corundum that is colored blue by trace amounts of titanium and iron. Aluminium is not stable in an oxygen-rich atmosphere AT ALL. It will immediately oxidize on the surface and form aluminium oxide, which is corundum. But because this corundum layer is very dense and forms a barrier that keeps the other oxygen away from the other aluminium, this process stops quickly, leaving only a *very* thin layer of oxide instead of rusting away the whole enclosure as would be the case with iron. So, sadly, no naturally growing sapphire crystals on enclosures...


To get back to the alum idea: I would suggest growing alum crystals on the enclosure, so that it is completely encrusted. Then put that into epoxy, so that the whole outside (not the inside, obviously) is encased in an epoxy block. Wait for that to harden, then put the whole thing in water to dissolve the alum. The aluminium enclosure should now fall right out of the epoxy block. Clean the epoxy block on the inside with more water. There are now "negative alum crystals" in the epoxy. Let the whole thing dry and then fill the negatives with colored epoxy. Put the aliminium enclosure back in while the epoxy has not set yet. Grind and polish the outside of the epoxy-encased box after it's all hardened. You now have the shape of  crystals preserved in colored epoxy protected by clear epoxy. A lot of work but a whole lot easier (in terms of necessary equipment, at least) that the emerald or sapphire variants.


Hope that helps,
Andy

p.s.: No, I'm not kidding. 

[EBK]

To get back to the alum idea: I would suggest growing alum crystals on the enclosure, so that it is completely encrusted.

Seems like as good of a place to start as any.
Here is an enclosure brushed with Elmer's glue and dusted with alum.  Hopefully I didn't sprinkle too much. We'll see (I can always start over).


Update:
The enclosure is now in its growth tank, suspended by its own lid, some gaffers tape, and a chopstick. 

t=0 days.

I will check it in a few days.

[duck_arse]

it really should have its own webcam/channel/site thing. on the www. instead of pron.

[bluebunny]

Mr Stephen speaks wisdom.   

[EBK]

it really should have its own webcam/channel/site thing. on the www. instead of pron.

Here you go:

t=1 day.


That's the best I can do on my budget.

EDIT: (I refreshed it.   )

[bluebunny]

Here you go:

Genius.   

[deadastronaut]

following the 'live feed' ....

[tubegeek]

Super bingeworthy!

[vigilante397]

I was already planning on jumping in to follow this thread, now that there's a live feed I'm definitely in.