What's the best etchant for etching aluminum enclosures?

[esauvisky]

What do you guys think is the best etchant for aluminum enclosures? Why?

To my understanding, there are three common etchants: ferric perclorate, NaOH and muriatic acid with hydrogen peroxide.
I've already tried Ferric perclorate and NaOH, these are my results:

Ferric perclorate was very, very corrosive.
With the box submerged, it even etched protected parts of the enclosure.
Also, the etched surface came completely uneven, like waves.
I know I should try applying the etchant with a pippete, that's my next step.

NaOH was clean, with good lines, but way too slow/weak.
Took me 2 hours with the box submerged and I still screwed it when sanding as it was very shallow.
It seems to make a flat etched surface, which is good.
One problem I have is that I don't know what concentration to use, because here on Brazil we only have NaOH as caustic soda in little white rocks, and I don't have any ideas of how much should I dilute them.

Do you have any thoughts on this?

[pakrat]

Non diluted ferric chloride works great for me. The trick to etching is to heat the etchant and agitate the box as it is submerged. This makes it etch faster and probably more evenly. To cut down on the pitting and etchant getting under the toner, try painting over the toner in as many areas as you can. Slade has a great tutorial on etching boxes: http://www.diystompboxes.com/smfforum/index.php?topic=80962.0

[R.G.]

I bet difluorine dioxide would work a treat. 

Look up "Things I won't work with" and "FOOF", FOOF being the actual chemical layout of difluorine dioxide.

'Course, there might be some problem getting your resist to work well...

[psychedelicfish]

In what form do you get NaOH? If you get it in the form of drain cleaning crystals it dissolves aluminium pretty quickly.

[esauvisky]

Non diluted ferric chloride works great for me. The trick to etching is to heat the etchant and agitate the box as it is submerged. This makes it etch faster and probably more evenly. To cut down on the pitting and etchant getting under the toner, try painting over the toner in as many areas as you can. Slade has a great tutorial on etching boxes: http://www.diystompboxes.com/smfforum/index.php?topic=80962.0

Do you heat your etchant? I have seen many recommending against it. How long does it takes you to get a good etching?
Also, how do you cover your holes and exposed areas? Do shapies pens work well?

In what form do you get NaOH? If you get it in the form of drain cleaning crystals it dissolves aluminium pretty quickly.

I do get them in the form of drain cleaning crystals, but they are white, not blue like yours. And they seem pretty weak, even when adding the least as water possible.
Also, NaOH seems to dissolve nail enamel and sharpies paint. How do you cover your holes and exposed areas?

[samhay]

NaOH will definitely work (http://www.youtube.com/watch?v=gihAT6eXaoc) and there is no need to heat it as NaOH gets hot when it dissolves in water. It will also eat glass (but not most plastic), so be careful how you store it once it is wet. As to how much to use - you may have to experiment.
Wet NaOH and skin/fat don't get on very well - this is one way to make soap - so be careful with it. If you are working at concentrations of it that will quickly etch aluminium then you should probably be wearing gloves and safety glasses- we do when we play with it in the lab.

[Maik]

Try HCL!
15% and take 2 minutes to etch. Very fine lines. And please dont do it with warm water.
Take 50ml water and 50ml 33% HCL.
IMPORTANT: first water and then HCL or the HCL flies into your face. Wear handgloves and glasses!!! And do it outside, do NOT breathe the steam in.
Some pics (all made with HCL)
http://imageshack.us/a/img716/3489/030tvr.jpg
http://imageshack.us/a/img821/1290/bilders2051.jpg
http://imageshack.us/a/img718/4553/bilders2012.jpg
http://imageshack.us/a/img547/2180/022ro.jpg

[pakrat]

Non diluted ferric chloride works great for me. The trick to etching is to heat the etchant and agitate the box as it is submerged. This makes it etch faster and probably more evenly. To cut down on the pitting and etchant getting under the toner, try painting over the toner in as many areas as you can. Slade has a great tutorial on etching boxes: http://www.diystompboxes.com/smfforum/index.php?topic=80962.0

Do you heat your etchant? I have seen many recommending against it. How long does it takes you to get a good etching?
Also, how do you cover your holes and exposed areas? Do shapies pens work well?

In what form do you get NaOH? If you get it in the form of drain cleaning crystals it dissolves aluminium pretty quickly.

I do get them in the form of drain cleaning crystals, but they are white, not blue like yours. And they seem pretty weak, even when adding the least as water possible.
Also, NaOH seems to dissolve nail enamel and sharpies paint. How do you cover your holes and exposed areas?

I have never tried any of the other methods mentioned because I have a case of ferric chloride. Yes I do heat it but not to the point that it's hot and it definitely etches faster when it's warm. As others have mentioned, do the etching in a well ventilated area. I etch outside or next to my range hood with the fan sucking the fumes out next to an open window.

[Canucker]

I have used the same mixture of muriatic acid with hydrogen peroxide (50/50) as I use to etch boards with....I don't heat anything because it heats up on its own as its working...I'm not 100 percent happy with the results because I get some pitting...if you see on the photo attached...there is pitting where I used press n' peel blue but none where I used a stronger packing tape and nail polish....I nail polish over the edges of the tape to try to prevent the tape from raising...its really time consuming to paint everything with the nail polish and then remove it after. The pitting can look pretty cool but I'd love to be able to control it. I changed the mixture of acid to peroxide to make it weaker but the results weren't very good and I had to waste a lot of time sanding and then restarting. Also I found using marker to mask off areas is fine for pcbs but for the aluminum work it did NOT work.

[pakrat]

That looks great Canucker! I understand about controlling the pitting, it happens to me too and while prepping the box with paint and tape can be tedious, it is extremely important to achieve a clean etch. You have the pedal forever so the time it takes to prep is short compared to that. I should point out, that I heat ferric chloride to etch, I don't think that applies to other etchants. Your box still looks cool though, pits or not....

[Canucker]

That looks great Canucker! I understand about controlling the pitting, it happens to me too and while prepping the box with paint and tape can be tedious, it is extremely important to achieve a clean etch. You have the pedal forever so the time it takes to prep is short compared to that. I should point out, that I heat ferric chloride to etch, I don't think that applies to other etchants. Your box still looks cool though, pits or not....

Thanks for the compliment! I won't have all of my pedals for ever! Friends keep requesting I build them stuff! Its a shame that prepping them really isn't one of the jobs that gets faster (per box) if you do multiples. I mean I could populate the board of I'm guessing 8 of the same design pedals in the time it takes me to do 2 of different design. It seems people I know all want vintage rats after they hear mine (and some before!). I wish I made ten in one go rather then one..then another one...then two at once. I could have saved a fair amount of time.
I wanted to just do face plates with an etched design and hold them in place on the box by drilling holes in them and feeding the volume/distortion pots through. The steel that i tested this with didn't etch well though...the press n peel started lifting before the etch went deep enough to look good and it took a LONG time since it is much harder then the aluminum. I guess I'll have to find a thick enough sheet of aluminum and cut it to size.

[pakrat]

I'm no expert at all! I've only etched about 15 boxes so far and the first few were pitted badly. I think it will always be a learning process for me, but that's ok. Agitating the crap out of the box while etching really makes it go fast. The last one I did got so hot I couldn't even touch it and it etched in 5 min. Maybe it got hot from the evilness of........
THIS!!

[J0K3RX]

I'm no expert at all! I've only etched about 15 boxes so far and the first few were pitted badly. I think it will always be a learning process for me, but that's ok. Agitating the crap out of the box while etching really makes it go fast. The last one I did got so hot I couldn't even touch it and it etched in 5 min. Maybe it got hot from the evilness of........
THIS!!

Yeah, I think it's cursed! does spin around on the floor, levitate and spew green vomit?  

Does it come with a bud inside and some Zig-Zags? by the way - get that evil ho some chapstick, I think she got some killa cotton mouth!

[pakrat]

I'm no expert at all! I've only etched about 15 boxes so far and the first few were pitted badly. I think it will always be a learning process for me, but that's ok. Agitating the crap out of the box while etching really makes it go fast. The last one I did got so hot I couldn't even touch it and it etched in 5 min. Maybe it got hot from the evilness of........
THIS!!

Yeah, I think it's cursed! does spin around on the floor, levitate and spew green vomit?  

Does it come with a bud inside and some Zig-Zags? by the way - get that evil ho some chapstick, I think she got some killa cotton mouth!

Yes, yes, and..... yes!

[CodeMonk]

You should add one of these for etching (be it enclosure or PCB):



The most important part isn't visible in that picture.
I use an air pump from a fish tank.
This creates lots of bubbles, doing the agitation for you.
That black thing there is the floor padding  from a horse trailer.
Like this stuff : http://www.floormatcompany.com/trailers-mats-c-112.aspx

I drill holes through it slowly, and hook up the air pump.
Gives me lots of bubbles.

I haven't given enclosure etching a try since my first attempt a few years ago.
It didn't come out so good
(Although over the years, I have grown somewhat "attached" to it).

[pakrat]

Sick!! Now that is ingenious man. How well does it work?

[CodeMonk]

Cuts the etching  time in half, roughly. Especially the larger boards.
The little pink things in there are plastic toothpicks. They keep the PCB above that block.

[Canucker]

I gave away two fish tank air pumps this winter!!! stupid me!!! Looks like you misspelled Evil! 

[pakrat]

Doh! Well I'm sure you could find some pumps at the first garage sale you see    Wouldn't the base and toothpicks get gooped up with spent etchant over time, or do you clean it after using? I don't think that setup would like the ferric chloride much.

[CodeMonk]

I just rinse it out after each use.
That includes hooking up the air hoses to an outside faucet and forcing water through the whole thing.
Except the pump of course.

Also, I keep the pump at a higher elevation than the rest of it when I use it.
I read something about it siphoning after turning the pump off. I think that was in the pump's instructional doc.

The pump I have is 2200 cc per minute.
And it has two outlets. Both are used.
Cost me about $10 at Walmart.

Edit:
And that rectangular plastic container previously held potato salad from Walmart.
And the bigger round one held ice cream