The Armour Archive

Ok, I want to etch something so I went to Radio Shack and bought their circuit board etching kit. It comes with a plastic tub to etch in, and the tub has a lid. Can I close the lid while I am etching something?

Also, I think it's too cold outside to do this and was thinking of doing it in my basement. Is it ok to do this indoors? One hesitaion I have about doing this in the house is that I have cats that hang out in the basement all the time, and I want to make sure the fumes won't make them sick (and I don't wanna get sick either).

Thanks!
Cat

You probably don't want to put the lid on if it seals tightly. The eteching process does produce some bubbles which could build up in a sealed container. You can certainly set something on top to cover it, as long as it doesn't make an airtight seal.

It will work cold, just very, very slowly. I always do my etching with it indoors. There really isn't a significant fume problem using ferric chloride. Of course it is always better to vent fumes like this, but the volumes are very very small on the scale you are working in.

Jurgen

A quick search for MSDS Ferric Chloride in Google came up with the following:

http://www.jtbaker.com/msds/englishhtml/f1060.htm

If you believe MSDS sheets, you should wait and do your etching outside. That being said, I use ferric chloride in lab all the time and have yet to be irritated by it or the reaction by-products. Gloves, goggles, and work clothes are definitely a good idea. It chews through and stains lots of materials, including pyrex glassware.[/url]

Thank you both for the help! That website does pretty much have me convinced to do it outside. I don't want my cats to get sick and I would have no way of ensuring that they coudn't get into it. It's going to be a small amount, but better safe than sorry.

Thanks again!
Cat

It is important to note that the MSDS is for the pure crystaline solid. Hence they are talking about higher concentrations than you have and they are talking about dust exposure. In your case the diluted form will be safer and it is unlikely that you will have any exposure to inhalation of droplets. Not completely safe, just safer. The main thing I have found with the ferric is that it stains everything. I do agree that cats tend to like to play with things so where ever you do your experiments take precautions to keep them away. On the whole, ferric is much safer than acidic etchants.

Another option of course is to do it in you kitchen with the hood switched on. Diluting the solid acid with warm water rather than cold significantly speeds up the process. The rule of thumb here is 10°C warmer (18°f) doubles the speed. The etching i´ve done on pattern welded blades with this stuff is done at most in a matter of minutes, so you´d have to stay on top of the process anyway, its not like your cats would drink the stuff while you´re off buying dinner. But of course, do it in a way you feel comfortable with.

Yes, this IS the diluted stuff, or at least it's the liquid form and NOT the solid. Will the liquid still etch the piece (it's brass) in a couple of minutes? I want a deep etch, so I figured that would take longer, but if it's only going to be about an hour or so, I could watch it while it's "cooking" to make sure nobody gets into it.

Another question - The instructions say to discard the solution once you're finished, so does that mean it can only be used once? The reason I ask is because the bottle is not all that big, and I will probably only get a few batches out of it if I keep throwing the solution away after each batch.

This stuff won't eat through plastic will it? That's what it came with, a plastic container, but since this is for etching thin metal on circuit boards, I don't think it's meant to hold the solution for extended periods of time (or that's my guess anyway). Well, now that I think about it, the bottle is plastic although it's a different kind of plastic.

Anyway, thanks again! I'm glad I decided to ask!
Cat

the radio shack stuff (I've used a LOT of it) will take 15-30min for a deep etch in brass if the its warm. Best way to keep it warm is toput the container you are using to etch in in the sink then run hot water in the sink (drain open). radio shacks etchant can be deluted half and half with more water to and still work good. Fumes are barely noticable in my experinace but an open window or vent isn't a bad idea. My suggestion for your piece of mind and safetys sake is to do your etching the in the bathroom with the vetn running, you can closet he door and keep the cats out and the vent will remove what little fumes there are. Pluss theres the tub or sink to put your container in.

No you dont need to discard it after one use, though it does loose some of its ability to etch with each use.

Nope it wont eat through plastic, I've a large storage container that has a gallon or two of it out int he garage thats been there for months.

Cann't wait to see how your project turns out in the end. Its looking good so far.

Hey Cat,
Whenever I have used PCB to etch it usually takes about 15 to 30 minutes for a nice etch in brass at room tempurature. Wait longer and you can get undercutting and a rough edge. One thing is to keep brushing off the buildup as it slows down the etch. I kept using the same acid for awhile, I think storage is the issue most have with reuse. I know there are several things you can use to mask, paint pens, vinyl stickers, asphaltum, one thing I used to use alot of before desktop publishing rendered them obsolete is dry rub on transfers, with an old english font it looked impressive and clean. Best of luck, when you have tried this try electric etching, I think it is more versatile.

Ok, since it doesn't take too long, I think I will do it in the kitchen. Except right now my hubby is stuck under the kitchen sink "fixing stuff". I can still amuse myself by poking him in the belly as he's working. Good times, good times..............

Zweihammer - someone sent me a link with instructions for the car battery method and it sounds pretty easy to do, PLUS I don't have to buy anythign special, just table salt.

Thanks guys!!
Cat

Hi Cat, I did not work with the FC directly but would often help swap out round dies for printing. We made spray tanks that were fairly well sealed except where the motor drive was attached to the side of the tank. The small opening here allowed fumes or mist to get out of the the plexiglas tanks and was very corrosive to everything metal in the room. Screw and nail head, light fixtures, all were rusting. The concentration of the FC is unknown to me, but it did do a job on the metal in the room. Some of the guys working with it aon a regular basis did occassionally get rashes on the inside of their forearms. Hope this give some insight about its hazards.
Good luck with it , Gene

If you are worried about the cats, get a container with a lid, and drill a couple dozern holes in the top. gas goes out, cats don't get in.

Alternately, you could just drill a single hole, fit it with a rubber grommet, and use a brewers airlock.

-+G