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Ferric chloride in etching


#1

Got some ferric chloride from Radio shack, and it was great for
just etching one piece of copper ( 4" x 4"), Tried to use the same
batch for another etching of a piece the same size, and only got a
very feeble etch. After 8 hours still not much going on. Then
finally decided to go to bed and checked it the next morning. The
ferric chloride had all crystalized, and the etch was still feeble.
Cleaned the mess off and got a fresh bottle (from radio shack),
great for one etch, lousy for the next. My questions are:: How
many times can one use the same batch???, Is there a shelf life for
Ferric chloride?? Can it be that mine was old??? What about the
strength. Does ferric chloride come in different strengths? ( I
used it full strength, but could it be that the stuff from Radio
shack is diluted???) Lots of questions I know, but I am sure that
with your combined wisdom, you will solve my problems. Thanks a
million (and special thanks to Hanuman for making all this possible)- Alma


#2

You should be able to get many etches out of one batch of ferric.
Ferric chloride breaks down in air. Make sure that after each batch,
that you pour the ferric back into the bottle and shut it tightly.
Instead of Radio Shack, try an electronic/computer parts store that
doesn’t sell cell phones, just parts. They will probably have a
better grade of ferric than Radio Shack.

-k
Karen Christians
M E T A L W E R X
10 Walnut St.
Woburn, MA 01801
Phone:781/937-3532
Fax: 781/937-3955
http://www.metalwerx.com/
Accredited Jewelry Instruction


#3
 My questions are:: How many times can one use the same batch??? 

You can use the solution repeatedly, as long as the pieces are not
sitting in the precipitate. However, as the solution works (etches)
it does lose strength. You can freshen the strength by adding dry
crystals. I allow my solution to settle out occasionally, decant the
liquid from the precipitate (solids), and add fresh crystals to bring
the solution up to 15-30 degrees on the Baume hydrometer.

Is there a shelf life for Ferric chloride?? 

I’m sure there is, but I’ve been using the same solution, with
addition of crystals or distilled water for my specifications since
1996.

Can it be  that mine  was old??? 

I don’t think age has as much to do with it as much as strength.
Keep it in a tightly sealed container and in the dark. It does have
components of chlorine that can be affected by sunlight and/or heat.

What about the strength. Does ferric chloride come in different
strengths? 

Strength of the solution definitely plays a part in how well the
solution etches. A stronger solution etches quickly, but can leave
striations in large open areas. A weaker solution will etch more
slowly, but can lead to undercutting of fine pattern lines.

You can get ferric chloride crystals from a chemical supplier in a
large city (may have to complete a form telling how it will be used
and documentation), or from an electronics supplier, such as Jameco.


#4

I have used the ferric chloride from Radio Shack for some years and
have always gotten many etches out of one bottle. I use a plastic
shoe box for etching and keep the lid on while the etch is going on.
When finished I refunnel the ferric chloride back into the bottle
and cap it tightly for storing in a closed cabinet. I have noticed
that after many reuses that it takes somewhat longer for a good etch.
But definitely can be used more than once. Are you covering your
ferric chloride while you are etching?

Kay


#5

As a Tech teacher in middle school we used to heat the solution
slightly for faster etching. Don’t let it boil and be sure to vent
it extremely well.

Al.