Muriatic acid/hydrogen peroxide + copper = Cupric Chloride. But how smelly is it

[Skruffyhound]

Well here's mine. I'm also impressed by Peps's no fuss approach. Between this and the UV light box there hasn't been much soldering going on this month. I'm also working on a photoresist/salt etch for enclosures, so it's been more chemistry than electronics for a little while.
I'm really hampered by new restrictions (anti-terrorist measures) in Denmark making it really difficult to get chemicals that were readily available not so long ago. After searching quite intensively today, it turns out that it's impossible to get a stronger solution than 3% Hydrogen Peroxide, so I'll have to go with that, and it comes in fairly small quantities. Not good considering the size of this tank
I also couldn't find a heater that could get up to the fish killing 45 degrees so I'll have to make do with 35 degrees.
The bubble pipe at the bottom is 4mm compressed air line drilled with a 1mm bit at 6mm intervals. A little erratic but possibly good enough. I couldn't find any info on aquarium stones and interaction with acid so I went with this system to begin with.
The plexi is 15mm sides and base and 6mm front and back panels. I actually drilled/tapped and bolted it together in addition to the silicone. Probably overkill, but I just felt more comfortable with some more obvious mechanical strength, and it made construction easier.
Thanks for the good info everyone.

[ralley]

If you use the 3-9% hydrogen peroxide you get from the drug store you will certainly need a bubble tank to re-oxidise the solution if you plan on using it continuously as a etchant .....the peroxide is oxidizing the copper metal and after you've dissolved the copper into the solution, and used up all the peroxide, the copper chloride does most of the etching for you: CuCl2 + Cu -> 2 CuCl. hence the bubbler giving you oxygen without having to add more hydrogen peroxide (as its really 60-97% water your adding, and diluting your etchant)   

Thanks for that explanation, I've wondered why I've always only been able to etch with the primary reaction, finally I know.  Off to track down some stronger hydrogen peroxide now...

Cheers, Rob.

[robmdall]

Peps, you rock. Thanks for the help. Nice etch on the enclosure also!!

rob

[robmdall]

Scruffy, now that is a sweet tank. I have had a concern about using silicone to seal a tank, but you and Peps confirm it is OK.

Thanks guys.

Rob

[caspercody]

Sorry, off question here.

What paper are you using for your transfers?

I was using Staples, but now I read the new stuff is terrible.

Also, anyone use the Radio Shack etchant? That's all I use in a Tupperware container, but wondering if that bubblier would be okay with that stuff?

Thanks
Rob

[peps1]

last paper i used was torn out of an IKEA catalog 

[Skruffyhound]

I got going with this and found that even after start up it has a distinct smell. Too much for me to have just standing around in the workshop. Another problem (I've read others on the net with this question) is how to store this when not in use since at least while the mixture is warm/in good etching condition, it continues to produce a gas, so it can't be kept in a tightly sealed container.
A third question mark over this might be - what gas is coming off it? Is it combustible/corrosive or for example oxygen that might increase the risk of fire. Interesting for me since I need to weld in the same room.
I'm not disagreeing with Peps, it may just be a question of scale, he has what looks like a couple hundred milliliters and my tank takes 2.5 liters.
Just a note for anyone starting to work with this, more later when I get home.

On the positive side, this stuff ate a 2x20x200mm  solid copper plate strip in about 6 minutes. Mine needs heat to work though, its still snow weather here.

[StereoKills]

Also, anyone use the Radio Shack etchant? That's all I use in a Tupperware container, but wondering if that bubblier would be okay with that stuff?

The Radio Shack etchant is Ferric chloride which doesn't require a bubbler.

[peps1]

I got going with this and found that even after start up it has a distinct smell. Too much for me to have just standing around in the workshop. Another problem (I've read others on the net with this question) is how to store this when not in use since at least while the mixture is warm/in good etching condition, it continues to produce a gas, so it can't be kept in a tightly sealed container.
A third question mark over this might be - what gas is coming off it? Is it combustible/corrosive or for example oxygen that might increase the risk of fire. Interesting for me since I need to weld in the same room.
I'm not disagreeing with Peps, it may just be a question of scale, he has what looks like a couple hundred milliliters and my tank takes 2.5 liters.
Just a note for anyone starting to work with this, more later when I get home.

On the positive side, this stuff ate a 2x20x200mm  solid copper plate strip in about 6 minutes. Mine needs heat to work though, its still snow weather here.

Interesting stuff bout the smell Skruffyhound.......can you describe it? I have a 2L glass bottle of etcher i use for larger jobs, and i get nothing more then a little metallic smell from it?  

I think the gas is hydrogen, so dont smoke over that big tank of yours  

i store my stuff in a big le parfait jars under the sink (it stops producing gas after a couple of days...so lid pops when you open it, but the build up of gas is easily contained in the jar.....in my case)

[burningman]

I built a plexiglass tank for muriatic acid too but was told that it may not hold. I used the epoxy that melts/fuses the corners together.
Let us know how this works for you. I might be worried that it would disolve the plexi but who knows, maybe it won't.
Good luck

[David]

What strength of hydrochloric acid do you use?  The 3% or less you buy at the drug store?  I swallow my pride and get 40% from the beauty supply.  With that much catalysis going on, you don't need a bubble tank. 

Do you mean 40% hydrogen peroxide?

If you use the 3-9% hydrogen peroxide you get from the drug store you will certainly need a bubble tank to re-oxidise the solution if you plan on using it continuously as a etchant .....the peroxide is oxidizing the copper metal and after you've dissolved the copper into the solution, and used up all the peroxide, the copper chloride does most of the etching for you: CuCl2 + Cu -> 2 CuCl. hence the bubbler giving you oxygen without having to add more hydrogen peroxide (as its really 60-97% water your adding, and diluting your etchant)   

I don't think so...

It's the muriatic acid that's doing the dissolving.  The hydrogen peroxide is a catalyst to jump start and speed up the reaction.

[Skruffyhound]

Sorry about the long hiatus, I just got chicken pox from my kids, at the age of 42!
@Peps, the smell is err ..... metallic and chemical, it's not bothering me too much while it's cold but when it warms up I notice it quite alot.
On the bright side, I'm welding right next to it, so it doesn't seem to be producing much flammable gas.

Anyone else building a tank - forget the fish tank heater unless you want to run it all the time, I just stick a floor heating fan right behind it to get quick heating results. Also, although my bubble system works well to agitate, I suspect it is not getting much oxygen into the mix and since Peps aquarium stone is the best solution I've seen anywhere I'll be adding a string of them when I get a chance.

Actually, if I was doing this again, I would build a flat system. Like my tank but on it's side (bit smaller perhaps) with Peps aquarium stone idea. The only advantage of the vertical tank is in making double sided boards.

[peps1]

How much dose heating it speed up the etch for you?

I put my etching tank into another larger Tupperware of hot water (bain marie style)....didn't notice it etching faster, but that metallic smell really became noticeable.

think i will sick with room temp & less smell 

[Skruffyhound]

Mine's doing very little at room temp, after the initial catalytic reaction, which creates heat, it slowed right down. I'm working on other things right now, I'll have to fiddle with it some more.

[Brymus]

Hah I read someone couldnt get more than 3% peroxide in an earlier post...
Well a couple of weeks ago I went into the Sally beauty supply in the strip mall across the street,and asked about 30% peroxide
And the girl said she couldnt sell it to me because I wasnt liscened beautician (I guess it was stamped on my forehead  )
So then I asked about muratic acid,suddenly the older lady working the register freaked out "ARE YOU MAKING BOMBS ?"
"WHAT DO YOU WANT THAT STUFF FOR ?"
I tried explaining what it was for but she was to busy trying to find the number for the FBI, who said terrorist havent succeeded in making
our way of life different?
Really this lady was in a frenzy just freaking out when I left.

BTW Scruffy that tank looks really nice I hope it works the way you want.
I wish I could afford to get this http://www.web-tronics.com/lowcosetsysw.html
Maybe in a few months,it has it all heater,bubbler tank

[MR COFFEE]

Hi guys,

Is there any reason to not use a glass tank to etch with the Muriatic and Peroxide bath?

I picked up a glass tank for etching pcbs that is rectangular in shape, about 10" x 2.5" x 15" deep at the World Imports place (I think they sell it for use as a vase for flowers or something). Makes a good etching tank using Ferric or Ammonium Persulphate anyway.

I'm surprised that I haven't seen them mentioned around here. It was about $20. Can't leak unless you drop it or the etchant can eat a hole through the glass or something. Can't be much more than buying the materials to make one.

mr coffee

[John Lyons]

Glass is fine for etching. Just more fragile and breakable if thin.

[Brymus]

OK I found out I can buy VL 20 (from Sally beauty supply) which is 20% hydrogen peroxide,
Online you can buy 35% peroxide as food grade but haz shipping is expensive...
And Leslies Pools carries 29% Muratic Acid for pool cleaning.
Also I read you can freeze 3% peroxide this will yeild 6% peroxide, then freezing again will yeild about 10% peroxide.
Each freezing you are loosing about 50% volume as ice,so to get 10% peroxide you will end up with 25% of the volume you started with.

But after alot of reading,this stuff DOES make bombs,and copper is used to activate it. 
Mostly in torpedoes and rockets its used as propellent but the peroxide will explode when it comes in contact with metals like copper.
It has sunk more than one sub this way.
So just how dangerous is making etchant from peroxide and muratic acid ?
And do you guys heat your etchant to speed it up?
I want to do this ,but I want to be safe ,so please educate me >as online the info is sparse at best and mostly about using it for propulsion.
Thanks ,Bryan

[peps1]

3 or 6%  peroxide is fine, no need for high percentages used in explosives, its only roll is to speed up the oxidation cupric chloride  .