Administered by Hale Sweeny (firstname.lastname@example.org)
This list digest contains the following message subjects:
1. LapDigest News for Issue No. 115 -
2. NEW: ELECTROFORMING (METAL PLATING) ON LAPIDARY
Subject: LapDigest News for Issue No. 115 -
I am pleased to present, below, a paper by George Butts on
electroplating on lapidary materials. If you will remember,
we presented an outline of methods for decorating lapidary
surfaces in Issue 110. That outline was (without the notes):
. Polishing the Surface
. Engraving, Etching or Incising a Design by
-Sandblasting the Design
-Engraving or Carving the Design
-Acid Etching the Design
-Texturing the Surface
-Incising a Design into the Surface
. Adding or attaching something to the surface
-Painting a design, or coloring
-Using photo-transfer techniques
-Doing metallic deposition by sputtering
-Glueing or attaching "things" to the surface
-Gilding or applying gold or silver leaf
>>> -Doing metallic deposition by electroplate
This paper describes how George does metallic deposition on
stones (and other non-conductive surfaces) by electroplating
(see ">>>" above.) Dalmar (references and addresses
the paper) has an overly expensive video on this process
which should be studied, if you are seriously want to learn
about this method. You may order a catalog from Dalmar using
the e-mail address given.
The paper George has written is a fairly complete
how-he-does-it description, and I am proud to run it here.
Subject: NEW: ELECTROFORMING (METAL PLATING) ON LAPIDARY
George Butts <email@example.com>
1. Source of DC current:
a) If it operates on standard household voltage,
117v AC, it's primary function is to:
1. Transform voltage down to safe level (below 50v).
2. Convert alternating current to direct current.
3. Filter to give a totally smooth DC current.
4. Shock hazard isolation (does not use a variable
transformer with a common input/output line).
b) Current (Amperage) sufficient for largest intended
c) Current (Amperage) control from 10ma to machine max.
d) Current (Amperage) meter readable to 2 significant
e) Protection from shorting of output leads and from
f) Two color coded leads to connect machine to the work.
Red = Positive...to anode
Black = Negative...to cathode (the work)
a) Pilot light
c) Voltage control
2. Conductive Paint.
a) Rio Grande silver lacquer 335-068
3. Plating NON-CYANIDE Solutions... aka "acidic" solutions.
a) Dalmar C1 Copper
alternate Rio Grande Electroform Copper 335-074
b) Dalmar C2 Nickel
alternate Rio Grande Electroform Nickel 335-078
c) Dalmar C3 Silver
alternate Rio Grande Electroform Silver 335-018
d) Dalmar C4 Gold 24k
alternate Rio Grande Electroform Gold-24k 335-054
alternate Rio Grande Electroform Gold-14k 335-053
24kt gold from Rio Grande is darker and rosier
compared to Dalmar. I prefer the brighter golden
yellow, others think dark is "richer"
e) Dalmar Acid Dip
alternate Rio Grande Acid Dip 335-075
f) Dalmar Electroclean
alternate Rio Grande Electroclean 335-076
g) Dalmar Copper Brightener B6
alternate Rio Grande Copper Brightener 335-065
h) Dalmar Nickel Brightener B7
Dalmar Mfg Co Rio Grande
4. Plating Anodes.
c) Stainless Steel
5. Jars, wire and miscellaneous.
a) Closable plastic or glass containers sized to immerse
b) Uninsulated copper wire to suspend work (about 24ga).
c) bowls for rinsing and holding
d) simple calculator, measuring calipers
e) Midas Plating Guide (Rio Grande 550-289 $8.95)
1. Pre-test sample of proposed "rock" against
decomposition in the plating bath.
2. Form "rock" into final "work".
3. Attach metallic circuit connector to the work. See
discussion below on suggested attachment detail
under "CONDUCTIVE PAINT AND 1/10 AMP PER SQ.IN."
5. Measure work and calculate plating in square inches.
4. Paint plate area with conductive paint.
Paint must present an electrically continuous circuit.
Paint must include (at least) the tip of circuit wire.
Paint must dry fully (9-18hrs).
Painted area should not be touched by bare hands after
5. Copper Plate
a) Measure and Calculate work plating area.
Set current for 1/10 Amp per square inch.
simple perimeter example:
4.3"around x 0.12" wide = 0.52 sq.in. area
required current = area/10 = 0.052 Amp (or 52 ma)
b) Connect red (+) rectifier lead to copper anode, then
immerse anode into copper plating bath.
c) Connect black (-) lead to work, TURN ON CURRENT
d) Immerse work (cathode) into bath.
e) Time plating duration to desired thickness
6. Remove work, rinse well in tap water, acid dip, rinse,
submerge and store in clean water until next plating.
Remove anode, rinse well, dry and place in storage.
Remove bath, wipe up drips, close tightly, store.
Copper Notes: expect bright, "fresh burnished" metal on
all painted areas. Dull, rosy finish due to current
too low. Dull, dark, loose or "powdery" finish from
current rate too high. Air drying now can cause
desensitizing of surface (keep in wet storage).
Any ragged or sharp plating edges must be smoothed here.
Use a very fine file, 600 grit SiC paper or the like.
7. Color Plate (Silver or Nickel+Gold)
.open next bath, connect and insert next anode.
.pre-set current to proper value.
.remove work from water bath, touch off drips.
.attach black cathode lead to work.
.WITH CURRENT ON,immerse work.
.time plating process for desired thickness.
Silver may be plated directly onto copper.
Silver plating requires stainless steel anode.
Reduce current to 1/8 current used for copper.
Plating time (suggested) is 10 min.
Gold notes (Gold must be plated over Nickel plating.)
Nickel plating requires nickel anode.
Current level for nickel is same as copper.
Plating time (suggested) is 30 min.
Gold plating requires stainless steel anode.
EXCEPT Rio 24kt which requires carbon anode.
Current level for gold is 1/2 current for copper.
Plating time (suggested is 5 min.).
CYANIDE, Sodium/Potassium salts
The process of metal electrodeposition requires a complex
bath composition for a smooth, adherent plate. Cyanide is
an inexpensive, excellent aid to this process for most of
these metals and of wide general usage. Plating solutions
with cyanide are sold side by side to those without. In
some catalogs, this distinction is not clear. Dalmar
Manufacturing currently says they have no "cyanides" in any
of their solutions. Rio Grande is very clear as to which of
their products contain cyanide. Rio Grande offers an MSDS
sheet with a statement of hazard with each plating product,
ask for it!
Cyanides are classed as a "violent poison" at 0.015 g/Kg
lethal dose with intensely harmful effects at lower dosages
(ingestion, inhalation, through broken skin). A solution
with cyanide will release Hydrogen Cyanide gas, of "gas
chamber fame", if mixed with an acidic solution. Cyanide
antidote kits, hazardous in untrained hands, are available
but require a prescription. Cyanides are a Federal Banned
Hazardous Substance with substantial penalties to anyone who
brings such into an inhabited dwelling and there is a very
high safety liability to industrial shop managers. Cyanides
MUST be disposed of by chemical degradation ONLY.
Good plating baths are now available which contain NO
CYANIDE, are competitive in cost and, for lapidary
electroforming, do an equally good job.
In summary: you MUST NOT USE electroplating solutions
containing CYANIDE both by reason of inherent danger and
Federal law within an inhabited dwelling or anywhere
children or "uninformed adults have access".
GENERAL SAFETY AND GOOD LABORATORY PRACTICE
Follow the safety instructions from the supplier. It is
known that some persons have an allergenic skin reaction
from contact with certain metals. Gold and nickel salts are
known to often be a problem. Some people develop such
reactions by repeated contact (allergenic sensitizing).
Most plating baths also have either a fairly acidic or
Keep your body, especially eyes, out of contact. Don't
bring food into the plating area. Wash your hands after
plating. Keep solutions well marked in proper containers.
Don't let anyone "fool around" with the solutions and
apparatus, children or visitors especially. Watch out for
spills into which a pet or child could step. Spills can
result in dried metallic salt powder becoming airborne with
bad consequences when inhaled.
Even though I don't heat the baths nor allow a current rate
so high that "fizzing" from gas evolution happens, I made a
plexiglas box (20"x20"x12") with doors as a chemical hood
contain the plating. I made this from $1/lb scrap
plexiglass (scrap bin from Dayton Plastics). Any spills are
easily wiped up. It's best NOT to work on a porous (wood)
table that will absorb spilled chemicals.
You should wear protective attire, including gloves, an
apron, and goggles. DO NOT use or store these products in a
household, garage, or other area where children, uninformed
adults, or pets may have access. All plating solution
containers should be properly labeled. MSDS sheets should
be available to all workers (posted).
SOME ROCKS DECOMPOSE IN THE PLATING BATH(S)
Keep a half-ounce of the copper solution out in which to
test the proposed rock (type). Drop a chip of a proposed
rock into this and watch for gassing or fizzing like chalk
in vinegar. After a half hour or so, remove the remains (if
any), rinse, dry and examine. Some stones like Lapis just
quietly and slowly disintegrate. Some discolor. A rock of
complex composition might only "etch" in one zone or strata.
CONDUCTIVE PAINT AND 1/10 AMP PER SQ.IN.:
The non-conducting rock ("work") is painted with a substance
which, when dried (or cured), conducts electricity. In the
plating process, electricity is fed to the coating through a
metal lead anchored to the rock. This lead may be part of
the work, like a glued-on finding or jump ring, or may be
held by adhesive to be cut free after the plating process is
complete. Be sure there is an electrical path between the
paint and bare metal lead. That is, watch out for adhesive
on the metal- paint over that and onto the metal itself.
Metal plate "grows" from the paint so uniformly that any
brush-stroke marks will be seen in the final surface.
Coverage should be only enough that, if painted on a glass
surface, would just be opaque. Thicker paint than that is
wasteful and there is some indication that it results in a
weaker plating job from thick paint cracking.
In reality, the paint film is poorly conductive. For this
reason, it is necessary to "baby" the process along with a
very gentle current flow as compared to standard
electroplating. A "hint" in the Dalmar Mfg literature
states that a current rate of 1/10 amp (100 ma) per square
inch is required. I agree and I think of this as the "100%"
rate. I find there is a current range around 100% where a
tight, bright plate is obtained. Care needs to be taken to
know the plating area and to pre-set the current flow
The current formulations from Dalmar, especially 24kt Gold,
have a wider window than Rio Grande but both work very well
at the 100% current rate. Sometimes it's very hard to
determine plating area, like a wrinkled or irregular
surface, and the extra latitude is important.
If a copper wire is used as a conductor to suspend the work,
like hooking through a glued-on finding, then the submerged
wire section will also be plated. It is good practice to
pre-paint the immersed wire with fingernail polish up to the
contacting hook. This is because the metal conducts so
well, relative to the paint, that it can drain current away
into the solution, "shorting" current before it can be
distributed into the paint. The symptom will be dullness at
the paint extremity.
The paint, remaining forever under the plate, must adhere
tightly or the metal overplate will loosen. The Rio Grande
silver lacquer adheres to many surfaces quite acceptably but
redissolves in strong solvents.
It is VERY important that the work be thoroughly cleaned.
Watch out for diamond paste polishing with its silicone oil
extender- especially tenacious! Silicone oil can be removed
with methyl ethyl ketone or lacquer thinner. In the same
vein, watch out for saw oil hiding in fissures or porous
areas. The dried paint surface is very sensitive to being
handled, easily becoming "desensitized" in dead areas where
metal just doesn't plate. This is probably due to invisible
substances from fingerprints. Thin cotton gloves, available
from photographic supply stores for handling film, could be
worn to eliminate a fingerprint problem.
Narrow plating on an inside curve (concave) may come loose,
especially if the work surface there is highly polished.
The only "fix" is to glue the plate back down with a
non-brittle epoxy (Vigor CE451) or block elastomer (E-6000).
COPPER and NICKEL UNDER GOLD
Copper is always the first metal plated on the work. Copper
is a pussycat in plating... it can be coaxed with ease onto
many surfaces and most things plate onto copper but watch
out for desensitizing of the fresh plate surface from
oxidation. After copper plating and rinsing, dip in
standard "acid", re-rinse, then store submerged under water
while waiting for the next metal coat. Copper is cheap and
strong so makes sense to build the appropriate thickness
with this substance before moving on to expensive metals.
Following copper, a case could be made that this is now
simple plating, no longer "electroforming", but it seems
that the current window is still very tight and careful
"current driven" plating continues to be necessary.
Silver can be plated directly over copper. Gold also CAN be
plated directly on copper but becomes irregularly discolored
with a little aging of the piece. One opinion has it that
copper "soaks" through the gold while another says that the
gold plate is, in reality, somewhat permeable and copper
tarnish products "sweat" into the overlaid gold metal
matrix. Bottom line is that an isolating layer of Nickel is
CURRENT SOURCE, THE "RECTIFIER"
Electroforming is "current driven". Current is the rate of
electrons flowing and measured as amperes ("amps"). Low
current levels are often referenced as milliamps ("ma")
where 1 milliamp is the same as 0.001 amp. The work is fed
electrons at a constant rate predetermined according to the
area to be plated: 1/10 Amp per square inch.
When we have a constant current regulator in the system, we
are uninterested in the "voltage", the pressure driving the
electrons. Without current regulation, voltage will need to
be turned up and down to maintain a constant current level.
This is something like working a water faucet to keep a
fountain at a certain height while the neighbors are
watering their lawns... it can be done but tedious over
A 3 amp system suffices for 30 square inches of plating area
which seems to be plenty for most lapidary work. For
example, to plate the bezel and finding of a baroque cab,
there might be calculated a plating area of 0.65 square
inches; thus, needing a current of 0.65/10 amps or 0.065
amps (65ma). On the other hand, the back side of a
desk-displayed geode might measure 25 sq.in., needing 2.5
An automobile battery or a moderate sized gel-cell would be
adequate as a current source but must be recharged after use
and stored under a trickle charge. Radio Shack sells a 3A
DC supply (22-504) for $39.95, regulated to present 13.8v to
the output and protected for shorting or overheating. RS
also has digital meters from about $50 capable of the needed
measurement range of 10ma up to 3 amps. For technical
types, a constant current regulator which plugs into the
circuit between the source and the work (in the positive
lead) can be easily and cheaply made from a few common
electronic parts. Mounting the parts in a case with an
adequate heat sink and so forth is not so easy without a
work shop and a bit of technical knowledge. Commercial
units tend to be quite pricey for electroforming use.
METAL REMOVAL; ROCK RECOVERY
If a problem happens that the metal needs to be removed,
remember the weak boundary layer of conductive paint. The
metal deposits on and into the paint surface but not
completely to the base rock. For Rio Grande solvent based
silver lacquer, immerse for a time in lacquer thinner (not
paint thinner) and the metal edges will become loosened and
can be plucked at. The metal plates as a "full hard"
substance, meaning it is rigid and doesn't peel away very
well but it can be freed with persistence.
HEAT & AGITATION
Unlike standard plating, electroforming solutions are
formulated to be used at nominal room temperature. Yes, for
optimum results, it is a good idea to rotate the work slowly
or periodically during the plating interval. This is
difficult to set up, especially with a "tree" of multiple
objects being plated simultaneously (when it might be most
needed). Be aware that bath geometry can make a difference
and the part(s) facing the anode can get more metal than the
BRIGHTNESS, BRIGHTENERS & PROPRIETARY ADDITIVES
Plating baths are complex and literature references are made
to "brighteners", a host of disparate chemicals, mostly
organic, having no "logical" reason to be in the
formulation. It is known that, for a given bath, small
amounts of these select chemicals assist in enabling metal
atoms to deposit as a smooth "prairie" rather than in
dulling "hills". Brighteners seem to deplete before all the
metal is plated out of a solution and the usable current
window tightens to an impractical level. Electroform
solution manufacturers sell their brighteners. If a good
plating solution goes bad too early, suspect the need for
brightener. Follow the suppliers instructions. Only a
small amount should be needed and too much can be as bad as
too little. Wow, is this witchcraft or what? Don't use
brightener from one supplier in the solution from another.
Don't mix baths like copper brightener in a nickel bath
unless specified by the manufacturer.
It is said that, for rocks which are sensitive to the
plating baths, the work can be dipped in a thin solution of
masking agent which dries to an invisible but protective
film. Conductive paint may then be applied and the process
continued as usual. I have had some success with
SCJohnson's "Future" floor wax, a solution of
ammonia-soluble acrylic polymer. It seems to be hardened
and toughened by the solutions, yet easily removed with a
wash of ammonia.
To make an unplated design in the metal, I have had good
luck drawing on the dried paint with a Sanford Ultra Fine
Sharpie (permanent) marker. After plating, it's a bit of a
problem to clean off the mark (and paint underneath) without
disturbing the adjacent metal but, otherwise, works pretty
CHECKING THE CURRENT WINDOW (TESTING)
When the plating process goes awry, tests are needed. The
idea is to plate one side (only) of something to which the
paint adheres fairly well and send it through the process to
check what's happening. I use waterproof laboratory paper
but smooth masking tape folded over on itself will also
work. Cut a strip of material 5"x1/2". Mark the backside
in 1/2" sections and paint the face with conductive paint.
When dry, 1/2" sections may be cut off to test copper
plating at various current levels around the 100% (25ma)
point. To test other metals, first plate copper over the
entire strip at 100% (2.5 sq in == 250 ma) for about 30
minutes. Cut coupons of this for testing silver or nickel.
To check a gold bath, plate a 10 minute layer of nickel over
the whole copper-plated strip and then cut the coupons for
When plating is halted mid-process and allowed to DRY, it
may lose activation where the next metal layer won't plate
or adhere to the first. The fix is to electroclean (follow
the suppliers' instructions), rinse well and follow with an
acid dip and final rinse. Electrocleaning solution is a
fairly strong alkaline cleaning bath. It works by applying
a strong current using a stainless steel anode (work is the
cathode) to get a clean surface, rinsing well and then acid
dipping to re-activate the existing metal. No guarantees.
TARNISH, ANTI-TARNISH AND PATINAS
Both freshly plated copper and silver seem to have a high
surface activity and it appears that they tarnish easily.
Consider that plated lapidary surfaces could be really
difficult to polish. As a last step in the process, a dip
into an anti-tarnish solution (and final water rinse) has
proven to be a good step. Dalmar Mfg offers a solution
(#C-9) as well as Rio Grande (#335-037). Rhodium plating
solutions (non-cyanide) are also available which give a
non-tarnishing top plate which, in theory anyway, is very
abrasion resistant. At more than double the price of 24kt
gold, rhodium is a serious anti-tarnish agent.
For the more crafty lapidists, all the colorful power of
copper patinas and silver aging solutions can also be
employed with this process.
I am not employed by, and have no commercial interest in,
any vendor mentioned in this document. I have no formal
training in occupational health or safety and all statements
herein represent my personal understanding and practical
experience. Anyone using chemicals or apparatus referenced
in this document, do so at their own risk and liability.
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