etchant stir

I think you came up with a very good idea. The magnetic stirrer is not a new idea but maybe it was for you. Keep thinking. Tom

i use rubber gloves so that i can "work" areas of the board that are persistent and have copper that doesn't want to etch off.

Chemists use a "stirring bean" which is basically a small bar magnet with an inert casing this goes into a beaker of liquid and is places on a base wiche produces a rotating magnetic field to stir chemicals automatically.

Bye. Jasen

I used an aquarium air pump and a bubble wand to keep things moving back in the day.

Jim

Yeah, saw them about thirty years ago already. We had even one build in a heating plate so you could heat (even boil) the liquid and stir it at the same time. Nevertheless it's an interesting DIY thing and I'd like to see a picture of it. After all, those 'professional' lab equipment comes with 'professional' price tags which are beyond most hobby budgets.

petrus bitbyter

Yes, the bubble wand is ok but it also causes a mist to rise from the tank. I knew of the chemistry lab stir and it is what I wanted to duplicate for a DIY etchant tank stir, to eliminate as much misting of etchant as possible. I'm just doing a small tank as of now to see how well it works out. I have seen a few post talking about a pump for the etchant tanks and wanted to share my approach to it. JTT...

Two things, if you are losing that much etchant from misting, you have the air volume WAYYYYY to high and 2ndly cover the tank.

Jim

I wonder if you could heat the soda cap after cutting it and flatten the fins while putting a little twist in them to form a crude impeller to maybe move more liquid.

etchant

standoff

cap

Good idea. As an alternative, just stick a grab tab on the PCB and allow PCB to float on the surface (don't trap any bubbles). Microwave the etchant beforehand. Takes about 8 minutes to do a 6" by 4" PCB. (and no, the solution wasn't fresh :) john

I'm thinking that sanding or scribing some indentations in the plastic and using epoxy would last longer. Silicon glue tends to peel off plastics.

Jasen Betts wrote:

I tried that about twenty years ago and had uneven etching patterns on my board around the vortex. Several aquarium air stones gave good bubbling dispersion.

That was the idea in cutting it, to make tiny fins like an impeller. On the other hand, instead maybe dissect a chipset cooler fan and set it into the silicone.

eBay and a little patience can significantly reduce that "professional" price tag.

Hello James,

My method of etchant agitation is to place "one side" of the square rubber bowl I use on a egg shaped cam mounted in a slow motor.BBQ

This will gently swoosh the solution back and forth.

I have an old etchant heated spray tank all corroded sitting useless. It did kick up a lot of corrosive mist.

My question, how do most of you home etchers dispose of the exhausted solution? Different areas probably have their own rules on this.

Good Luck,

• * * Christopher

Temecula CA.USA

did kick up a lot of corrosive mist.

I don't have the link, but somewhere I read about a two-step process that turns ferric chloride into rust and (I think) table salt. I think it uses baking soda and some other common household chemical... anybody got info on this?

Washing Soda. It's Sodium Carbonate, Na2CO3, and doesn't release hydrogen as it works. It turns the iron and copper ions into their carbonates, which are essentially just dirt, and the sodium eats the chlorine. :-)

I did a board once with about a pint of RS FeCl3, and just flushed it when I was done. The EPA hasn't shown up to clap me in irons, yet. ;-)

Cheers! Rich

They're on the way. In a black helicopter.