Non-temperature sensitive etchant...

[therecordingart]

Since I bought my new place the wife won't let me etch boards in the bathroom anymore. She was able to put up with an orange/yellow stained bath tub in our apartment, but now that we are homeowners she brought the hammer down.

It's that time of year (really friggin' cold), and I haven't installed a heater in my little garage workshop yet. I'm looking for an etchant that isn't temperature sensitive and is sharpie friendly. I could always put my ferric tank inside of a hot water bath, but why complicate something that can be simple?

Any suggestions?

[jacobyjd]

I think the muriatic/peroxide method ignores the temperature variable.

[rustypinto]

I use cupric chloride, which starts from Hydrogen Peroxide/ Hydrochloric acid. You don't have to heat it up, but all etching rates are dependent on temperature. This article is very helpful:

http://members.optusnet.com.au/~eseychell/PCB/etching_CuCl/index.html

You definitely don't want to etch this in your house with the fumes involved from the initial mixture of that stuff. Muriatic acid commonly has a 30% concentration, which can emit chlorine fumes when you open the container, and continues to do so when you mix it into hydrogen peroxide. Be safe!

When cold temperatures set in, i use a fish tank heater since i keep the garage door open when i etch. I've seen some elaborate sets ups with bathroom/ kitchen vents in place (and rightly so).

[R.G.]

In general, all chemical activity is temperature sensitive. I have sometimes solved the cold-garage problem by suspending a heat lamp over the etch tray, beaming down IR photons into the soup. The whole garage doesn't need to be hot, only the etch tray.

It helps a lot if you have a couple of buckets of water handy so that when etching is finished, you can dunk/rinse the board in first one, then the second bucket to remove most of the clingy etchant in it and both stop etching and avoid drip-spatters of etchant.

[Mark Hammer]

RG notes that the entire garage doesn't need to be hot, only the tray.  I'll narrow that down even further and say that the entire etchant bath doesn't need to be warm, just the etchant in direct contact with the board.  Any small halogen "study lamp" pointed at the board can do what you need it to do.  Just note that excessive heat applied to a plastic tray will deform it, so apply judiciously.

Here's a tried and true strategy:
1) Drill some small holes into the corners of the board to be etched.
2) With copper side facing down, stick some toothpicks into the holes so that the board turns into a miniature coffee table.
3) Breaks the ends of the toothpicks off so that the board will sit juuuuuuuuust below the level of the surface of the etchant bath.
4) Float the board, legs down, in the etchant.
5) Take a hair dryer or heat gun on low setting, and point device at the board from a safe distance.

I do this during the winter, and can etch boards in sub-zero garage temperatures.

[therecordingart]

Mark,

I appreciate it, and I've been there. I get impatient and I've blown etchant all over the place with the hair dryer before. 

[tiges_ tendres]

I put my Ferric Chloride in a zip lock bag which I suspend in a tupperware tray full of boiling water.

Once the etch is done, you can rinse the board off in the now cooled water.

[therecordingart]

I put my Ferric Chloride in a zip lock bag which I suspend in a tupperware tray full of boiling water.

Once the etch is done, you can rinse the board off in the now cooled water.

This is a great idea.

[R.G.]

I put my Ferric Chloride in a zip lock bag which I suspend in a tupperware tray full of boiling water.

Once the etch is done, you can rinse the board off in the now cooled water.

This is a great idea.

It is. Be sure you have gloves and some place non-fatal to dump the hot etchant/etc. if the zip lock fails to work perfectly.

How do I know this?

[tiges_ tendres]

I put my Ferric Chloride in a zip lock bag which I suspend in a tupperware tray full of boiling water.

Once the etch is done, you can rinse the board off in the now cooled water.

This is a great idea.

It is. Be sure you have gloves and some place non-fatal to dump the hot etchant/etc. if the zip lock fails to work perfectly.

How do I know this?

Indeed!  If you cheap out and buy the wimpy zip tops the sides tend to leak,  especially after repeated use.  Often the sides are heat sealed which increases the chance of the bag failing. 

Fortunately for me, my wife sees fit to spend my hard earned wages on only the finest zip top bags known to man.  And whilst I certainly enjoy the benefits of these Uber bags, I dont appreciate the evil looks I get as I skulk off back to the garage with something else I have taken from the kitchen, never to be returned.

[newperson]

I did the leaky zip locks and boiling water for some time until I got a fish aquarium heater.  This is a much easier and cleaner way than the bag method.  The only downside I can see is you need two or more bottles ($$$) of etchant for the tank.  You should get a side mount heater for this method, not the ones that stick to the sides with suction cups.  Just make sure you get one that makes it past 88 degrees.  Most of the normal suction cup heaters turn off at this point.  Also don't order one from mouser or allied electronics.  They will only send you the wrong item.  The ones they pictured are what you are looking for, but the one they will send you is different.  Look for an "Elite" branded side mount heater.  This is what I have been using for a while now.

A heat lamp seems even easier if you are working inside though.

[Johan]

I use an old retiered

put the etchant in the pot and it gets/keeps real hot..it does restrict the size of the board being etched, but that is rarely an issue with stompbox pcb's
j

[therecordingart]

I use an old retiered

put the etchant in the pot and it gets/keeps real hot..it does restrict the size of the board being etched, but that is rarely an issue with stompbox pcb's
j

Awesome!

[rustypinto]

The only downside I can see is you need two or more bottles ($$$) of etchant for the tank.

This was a tricky obstacle with my plastic cereal container from Walmart etch tank with side mount fish tank heater and bubbler. You can account for this using a flat (unobtrusive to the copper board that is), non-reactive-to-etchant object inside the tank to displace the extra volume needed otherwise.

In my case this object turned out to be a piece of delrin plastic from the machine shop i work in, but thats not very common (or helpful, sorry). I'm sure there are lots of other things out there just waiting to be used as an etchant displacer 

[Mark Hammer]

Mark,

I appreciate it, and I've been there. I get impatient and I've blown etchant all over the place with the hair dryer before. 

Then the study lamp is the obvious choice.

[therecordingart]

The only downside I can see is you need two or more bottles ($$$) of etchant for the tank.

This was a tricky obstacle with my plastic cereal container from Walmart etch tank with side mount fish tank heater and bubbler. You can account for this using a flat (unobtrusive to the copper board that is), non-reactive-to-etchant object inside the tank to displace the extra volume needed otherwise.

In my case this object turned out to be a piece of delrin plastic from the machine shop i work in, but thats not very common (or helpful, sorry). I'm sure there are lots of other things out there just waiting to be used as an etchant displacer 

Since an aquarium heater and bubbler is already used...why not aquarium gravel?   

[Cliff Schecht]

What do you guys usually do with your used etchant? When I was in an apartment I would just water down the etchant really thin and poor it down the sink but in a house, I just end up with little tupperware bins full of etchant. Eventually I fill up a bottle with used etchant but I've gotten away from pouring bad things down the sink, it's not a very enviro-friendly thing to do..

[Lurco]

What do you guys usually do with your used etchant? When I was in an apartment I would just water down the etchant really thin and poor it down the sink but in a house, I just end up with little tupperware bins full of etchant. Eventually I fill up a bottle with used etchant but I've gotten away from pouring bad things down the sink, it's not a very enviro-friendly thing to do..

type this into the searchbox:  dispose etchant

[Mark Hammer]

What do you guys usually do with your used etchant? When I was in an apartment I would just water down the etchant really thin and poor it down the sink but in a house, I just end up with little tupperware bins full of etchant. Eventually I fill up a bottle with used etchant but I've gotten away from pouring bad things down the sink, it's not a very enviro-friendly thing to do..

Not particularly plumbing-friendly either, if there is any copper pipes along the way.
Pop on down to your local bulk foods store and get yourself a pound of baking soda to keep in a coffee can near where you etch.  Good for mopping up spills too.