On Tue, Jan 27, 2009 at 12:45 PM, Peter <plpeter2006@yahoo.com> wrote:
> I used a tupperware/rubbermaid style hinged lid, tall, rectangular container to
> keep 1 liter of FeCl3 solution and made my boards in it for more than 2 years.
> The closed lid keeps air out and the solution viable for longer. Air will kill
> the solution faster than the boards you make.
>
> FeCl3 comes in pebble like rust colored lumps. You put them in the container
> and cover with water from the hot water kettle, and stir until dissolved.
> That's it mostly. If you want to be accurate get a liquid density gauge (the
> kind used for tomato juice is right) and adjust the density with water until
> it is just right (32 degrees Baume at 50 deg. C). Let it sit for a few hours
> before first use.
>
> My high tech way to do it X years ago was:
>
> 1. put a large pebble in the FeCl3 container so it won't float (see below)
> 2. put an old phone book on the floor (thermal insulation and spill soak-up)
> 3. put a 2-3l tupperware container on the phone book
> 4. pour +1l of boiling water from the kettle into the large container
> 5. put the weighted (pebble) etchant container in the large container
> 6. wait about 5-10 minutes for the etchant to heat up a little
> 7. put the board in the etchant container and etch for 20-25 minutes with
> occasional rocking. The board was hung by fishing line monofilament from a
> pencil or wood stick (brush handle) that sat on top the etchant container.
> Periodically remove the board to inspect it against a strong light for
> etching completion and problems. Drill a hole in the edge of the board to
> thread the monofilament through. The board should not touch the container
> while hanging in the etchant.
>
> My high tech way I did not implement (never needed it):
>
> 1. use a flat container for the etchant (tray like)
> 2. obtain a cardboard box that is slightly smaller than it
> 3. cut the lid off the cardboard box, line it with aluminum foil and mount a
> 40-75 Watt light fixture and bulb in it (wattage tbd)
> 4. duct tape the cardboard box to the bottom of the tray (around it) using
> heavy duty tape. The other sode of the box can be opened to change bulbs.
> 5. fill the bath with H2O, turn on the light, and use a liquid thermometer to
> get the right wattage that keeps the H2O at 45-55 deg. C indefinitely.
> 6. replace the H2O with FeCl3 solution and etch boards in style, while the
> light shining through the bottom of the plastic container allows etching
> inspection without removing the board, besides keeping the solution at the
> right temperature.
> 7. optionally add a $2 'cocktail stirrer' (with plastic stirrer paddle) to be
> clamped to the tray and agitate the solution.
>
> (you first saw it here)
> Peter
>
> PS: FeCl3 tends to corrode everything so it is a no shipping item. Obtain it
> locally from a chemical supply. It only costs a few dollars per pound/kg.
>
> PS2: Wrt toxicity and MSDS - compare the msds sheets of NaCl and FeCl3 :) :)
> (hint: salt is to be kept 'locked up' and is 'mutagenic to mammalian somatic
> cells' - the other ingredient of the solution is dihydorgen monoxyde, also
> dangerous when ingested in large quantities or inhaled)

Your high-tech way is genious. Bud do you think an incandescent bulb
of 40 - 75 watt will release enough heat to keep the solution at 50
degrees C?


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