Archive of the former Yahoo!Groups mailing list: 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