Some etching questions

[danrogers]

Hi all, I've never etched before but I want to make some simple pcbs.

I brought a kit from a high street store that contains a bag of sodium persulphate powder or crystals whatever.

Is this the same as ferric chloride? If not is ferric chloride better to use?

Also, once I've mixed up this sodium solution, will I be able to keep it in a plastic container and re-use it?

Thanks

 

[Hero999]

No, it's less messy than ferric chloride although the etch time is slightly longer and the solution doesn't keep for as long once mixed.

 

[danrogers]

ok thanks mate, i might try it but get some chloride soon

 

[vne147]

I have only ever used ferric chloride and like Hero says it is messy but it works well. I have etched some pretty small footprints before. It's not too bad if you take precautions like protecting counter tops, wearing rubber gloves, etc. I usually heat up the etching solution beforehand by submerging the entire sealed bottle into hot water. Then I put the board to be etched in a plastic container and pour the etchant over it. I then agitate the container by rocking it gently back and forth while holding it over a lightbulb as a heat souce. Just don't put your face directly over it because it's kind of nasty stuff. Also, never spill it on your carpet like I did because you won't get it out. I can't wait until I move out of my apartment and see how much $ they are going to take out of my deposit for that.

 

[Boncuk]

Hi vne147,

have you tried to get rid of the brown spots by applying natriumcloride (aka sodiumcloride), chemical forumula NaCl?

It should partly neutralize ferric cloride.

Try a weak solution of one teaspoon (~7g) of NaCl on one liter of lukewarm water and slowly increase to 10-15g.

Do not use more since then it will start bleaching the carpet.

Or yet a better idea: Bleach the entire carpet. Your landlord won't remember if he put it in.

Boncuk

 

[vne147]

Hi vne147,

have you tried to get rid of the brown spots by applying natriumcloride (aka sodiumcloride), chemical forumula NaCl?

It should partly neutralize ferric cloride.

Try a weak solution of one teaspoon (~7g) of NaCl on one liter of lukewarm water and slowly increase to 10-15g.

Do not use more since then it will start bleaching the carpet.

Or yet a better idea: Bleach the entire carpet. Your landlord won't remember if he put it in.

Boncuk

Let me get this straight Boncuk, you are telling me I can remove FeCl stains with plain old SALTWATER!!! That's awesome! I should have payed more attention in chemistry class. I'm going to try that as soon as I get home. I've tried many off the shelf cleaners and all I've succeeded in doing so far was spreading the stain around. I guess it doesn't help that it's a light colored carpet. I'll let you know how things turn out. If it works, I'll start petitioning to officialy rename saltwater to "Boncuk Juice".

Dan,

Even if the Boncuk Juice works, I'm going to stick with my original recommendation of not spilling any FeCl to begin with.

EDIT: I know all you guys with thousands of posts will probably laugh at this but, it's my 500th post. Yay!

 

[Hero999]

I would say that sodium persulphate is neither better nor worse than ferric chloride, it's just a different material with different properties; each has its advantages and disadvantages.

I've got a large container of sodium persulphate, I know it doesn't keep very long once diluted so I only make up as much as I need. It's slow but I'm never in any great rush so that doesn't matter. I've only ever used ferric chloride at school and college and it does etch well and keeps for ages once diluted but it's really messy.

If you have an area in your home or workshop you don't mind getting messed up and wear old clothes when etching then I'd recommend ferric chloride, but it you want to etch in your kitchen then I'd recommend clean sodium persulphate any day.

 

[Sceadwian]

Once the stain has set (dried) it's likely permanent. From what little I know I like the Ferric Chrloride method better, but that's primarily because I know where to dispose of the wastes it generates, not just safely, but beneficially to both parties.

 

[vne147]

Hey Sceadwian, how's it going?

Once the stain has set (dried) it's likely permanent.

No offense, but this is one time when I'm hoping you are wrong.

I know where to dispose of the wastes it generates, not just safely, but beneficially to both parties.

Care to elaborate? Making moonshine perhaps? Or maybe you have an unfriendly neighbor's flower bed that needs "watering"?

 

[Sceadwian]

I could be wrong, and for the sake of any stains you may have I do hope so as well => Depends a LOT on the material it got on/into weather or not it's simply a surface discoloration or weather or not it actually soaked into/chemically altered the material.

As far as disposal goes I used to work at a Metal finishing plant and I know the owner. Ferric Chloride is often used in the waste treatment process because it adds weight to some of the smaller suspended solids making the floc bigger and getting more of the heavy metals they need to remove out, so they get some free ferric chloride to help with the floc formation and the added copper will fall right out into their waste treatment stream adding neglible metal contenet and it's then turned into a sludge dewatered and dried into something that looks much like common dirt but with a decent amount of heavy metals and shipped off to a hazardous waste dispsoal site. I guess typically what they do is mix it with concrete to makme it harder for it to leach out into ground water and then it goes to special dumps rated for hazardous waste, all nice and legal like.

 

[danrogers]

cheers i think i will probably stick with the stuff i got then for the first few goes.

how did the stain removal go vne any luck? lol

 

[Boncuk]

Let me get this straight Boncuk, you are telling me I can remove FeCl stains with plain old SALTWATER!!! That's awesome! I should have payed more attention in chemistry class. I'm going to try that as soon as I get home. I've tried many off the shelf cleaners and all I've succeeded in doing so far was spreading the stain around. I guess it doesn't help that it's a light colored carpet. I'll let you know how things turn out. If it works, I'll start petitioning to officialy rename saltwater to "Boncuk Juice".

Dan,

Hi Dan,

I suggest to taste NaCl for a quick test. I doubt it will taste salty, but I'm sure it will bite your tongue. .
As a matter of fact natriumchloride is also used to produce soap.

It should at least do something to the spots on the carpet. I never use gloves when etching a board and my fingers, especially the finger nails turn brown. Using natriumchloride and washing my hands with the solution the brown colour disappears rapidly, burning the fingers a bit.

As an alternative you might try TESCO LOTUS bathroom cleaner (violet plastic bottle). I dissolves organic stuff without leftover.
(Saves funeral expenses as well. )

Applying some vaseline the fingers look like new.

If it does something good to your carpet you might go ahead and call it "Boncuk Juice".

Regards

Boncuk

 

[shortbus=]

Hi Dan,

I suggest to taste NaCl for a quick test. I doubt it will taste salty, but I'm sure it will bite your tongue. .
As a matter of fact natriumchloride is also used to produce soap.]

Isn't NaCl what the ancient Egyptians used to mummify bodies? A mixture of Baking soda and Salt?

 

[vne147]

Isn't NaCl what the ancient Egyptians used to mummify bodies? A mixture of Baking soda and Salt?

I'm not sure if it was used to mummify people or not but NaCl is just plain old salt. Baking soda is Sodium Bicarbonate or NaHCO3. Despite that fact, hopefully it will soon be used to clean my carpet. Sorry Boncuk, I've been working nights and haven't had a chance to try it yet. I will soon!