Homebrew PCBs

I had been aerating my CuCl etchant with a small vacuum pump used as
an air source. I was bubbling in my Coleman cooler half full of
etchant with the lid off, to ensure lots of air to aid with the
etching of the copper wire I am using to make the etchant.

I had heard that HCl fumes could damage metal in the proximity, but
had not seen any sign of this with nearby steel stock or tools with
the small vacuum pump.

I switched to a larger pump Saturday evening because I wanted to hurry
the process. This pump was so vigorous in aerating that some etchant
spattered outside the cooler, but this seemed minor. Later I
discovered that the pump was becoming quite warm to the touch, (the
pump body has lots of aluminum fins ; it was quite warm but it was not
painful to touch) and the air it was pumping was also being warmed. I
could smell fumes, so I put the lid on the cooler. There is enough
space in the hole in the lid around the sparger pipe to allow the
bubbling air to escape. I switched to the old pump to give the bigger
one a chance to cool.

Today (Sunday) I switched to the bigger pump at noon, again leaving
the lid on the coller. Tonight I discovered that many steel tools in
this room and the adjoining room (which is not sealed off, there is a
large entrance between the two) were being attacked by the HCl.

The tools etc had a fine coating of what looked like rust on many
surfaces. I rinsed these with a rag soaked in a solution of sodium
bicarbonate and rinsed them off with a bit of water. A slight polish
with extremely fine emory took the rust off, but I will have lots of
this to do.

What is the best way to deal with this rust and any residual HCl?

(Needless to say I turned off the bigger pump and swapped the old
small one back in.) 

Grant

You don't need to bubble with the lid off because fresh air
travelling through the tube is being introduced by the pump from the
outside.

Save your tools! I ruined a lot of expensive equipment a long time
ago by leaving an open bowl of Ferric Chloride out for a few weeks -
eveything metallic within a 5 foot radius was tarnished and rusted.

Have you tried adding hydrogen peroxide? See if that speeds 
your reaction.



--- In Homebrew_PCBs@yahoogroups.com, "grantfair2001"
<grant.fair@s...> wrote:

> I had been aerating my CuCl etchant with a small vacuum pump used as
> an air source. I was bubbling in my Coleman cooler half full of
> etchant with the lid off, to ensure lots of air to aid with the
> etching of the copper wire I am using to make the etchant.
> 
> I had heard that HCl fumes could damage metal in the proximity, but
> had not seen any sign of this with nearby steel stock or tools with
> the small vacuum pump.
>

grantfair2001 wrote:
> I had been aerating my CuCl etchant with a small vacuum pump used as
> an air source....

> The tools etc had a fine coating of what looked like rust on many
> surfaces. I rinsed these with a rag soaked in a solution of sodium
> bicarbonate and rinsed them off with a bit of water. A slight polish
> with extremely fine emory took the rust off, but I will have lots of
> this to do.
> 
> What is the best way to deal with this rust and any residual HCl?

HCl fumes make everything oxidize. About the only thing to do is vent
it out doors, or bubble the exhaust thru a secondary tank of water.

I can run an ABS plastic pipe from the cooler lid to a right angle
elbow, and then out through a hole in the basement window. How should
the pipe terminate at the exterior end? Will any HCl be evident at the
end of the pipe? (It would be at a level where a child could see and
touch it, and if it dripped it would be onto a concrete sidewalk.
SInce I rent I don't want to damage the sidewalk.)

Grant

--- In Homebrew_PCBs@yahoogroups.com, Russell Shaw <rjshaw@i...> wrote:

> grantfair2001 wrote:
> > I had been aerating my CuCl etchant with a small vacuum pump used as
> > an air source....
> 
> > The tools etc had a fine coating of what looked like rust on many
> > surfaces. I rinsed these with a rag soaked in a solution of sodium
> > bicarbonate and rinsed them off with a bit of water. A slight polish
> > with extremely fine emory took the rust off, but I will have lots of
> > this to do.
> > 
> > What is the best way to deal with this rust and any residual HCl?
> 
> HCl fumes make everything oxidize. About the only thing to do is vent
> it out doors, or bubble the exhaust thru a secondary tank of water.

grantfair2001 wrote:
> I can run an ABS plastic pipe from the cooler lid to a right angle
> elbow, and then out through a hole in the basement window. How should
> the pipe terminate at the exterior end? Will any HCl be evident at the
> end of the pipe? (It would be at a level where a child could see and
> touch it, and if it dripped it would be onto a concrete sidewalk.
> SInce I rent I don't want to damage the sidewalk.)

If condensation got acidified by the fumes then it will dissolve lime
in the concrete. The fumes might have a faint smell. If you have an
outside open pvc or clay drain then i'd put the hose into that. Another
way is to bury the end of the pipe under a mound of pebbles.