clad plate polishing?

[rivera1212]

hello all, happy new year!!!!

i was thinking about buying some clad plate from Mike R. but i have read they require a different method for polishing then my jeweler’s wheel.

can anybody tell how to polish these proper so i dont waste alot of money.

[Mike Robinson]

Steps for Polishing Clad Silver Plate

© Mike Robinson 2010

POLISHING CREAM – Nuvite Nushine S grade

Needed items:

Plate Polish – Nushine S

Random orbital sander with 1” foam applicator pad (set at 5 for the speed)

Cotton Velvet (German velvet $75 per yard)

1. Place two dabs of polishing cream on the plate surface with finger.

2. Pour a few drops of mineral spirits on the plate surface.

3. Place velvet pad on top of plate cut larger than the random orbital foam applicator pad or hand-finishing block.

4. Use the orbital sander set at #5 with a back and forth, north-south motion.

5. After polishing, clean the plate with velvet and mineral sprits.

6. Wash the plate with soap and water.

7. Clean the edges with towel.

8. Use velvet with water and soap to clean the back thoroughly

9. Use NEW velvet with water and soap to thoroughly clean the front

10. Rinse thoroughly, dry with flannel or soft towel.

Hand Buff

Needed items:

Two 3”X4” wide wood blocks each with velvet wrapped on them

Dry Powdered Rouge XX6 (Grobet USA 1lb. Zife)

Nylon stocking for the rouge

Lamp Black (for final buff)

Hand Buff heater (four halogen lamps with aluminum top)

Plastic fingernail brushes (to clean hand polishers)

Ethyl Alcohol denatured

First Stage: Hand Buff :

1. Place plate on polish stand or block.

2. Spray with Ethyl alcohol denatured.

3. Hand polish with velvet taped onto a woodblock in orbital motion.

Second Stage: Rouge Hand Buff

4. Place 2 dabs of rouge on plate (carefully spoon into the toe of a nylon stocking a small quantity of powdered rouge and tie it. This will make a small pouch of rouge. Store it in a jar that will keep out moisture) Use a hand block with velvet for rouge in an orbital motion.

5. Use the large rouge buffer (kept warm on the heater without rouge) 20 strokes in each direction as each side is rotated.

Final Stage: Lamp Black buff (lamp black at graphic arts supply)

6. Using the large buffer from the heater with lamp black sprinkle a little lamp black on plate and buff 100 times in the direction of the horizon and then rotate 180 degrees and repeat the 100 strokes.

Dust with a squeeze bulb type blower and the plate is ready for re-silvering.

The above methodology is what I am currently using. The cold roll clad process will cause some lint and debris to be impressed into the surface of the silver. The Random orbital polishing with velvet and Nushine S will remove the mill grain quite effectively. It will not remove the impressions. These rarely affect the results. If you are fastidious and NEED to make the plates as perfect as possible, then prior to using the Random Orbital sander, you can use 3M tri-m-ite graded abrasive sandpapers with a reciprocating motion BY HAND, to cut down the surface and remove the impressions before Random Orbital. I use 30 micron, 15 micron and 9 micron grades. For beginners, a delicate touch must be developed, I suggest that you only use 9 micron paper until you get the hang of it. A jewellers wheel will not remove mill grain or rolling impressions.

Re-silvering has been covered under a separate topic.

All the best, (thanks Irv for brining this post to my attention)

Mike Robinson

[Mike Robinson]

I forgot to mention that re-silvering is OPTIONAL, not absolutely necessary for fine results.

Mike

[rivera1212]

Mike,

thank you so very much!!!!! i will be calling to place a order shortly!!

[jgmotamedi]

Quote:

“Place velvet pad on top of plate cut larger than the random orbital foam applicator pad or hand-finishing block.”

Sorry, this confuses me. Are you constructing a pad covered in velvet? And is this pad what is larger than the plate?

[Mike Robinson]

Sorry for being unclear, these instructions were originally written for people that attend my workshops. They can see the equipment and how it is used.

 

For clarity, allow me to use the term polishing to refer to the use of the Random Orbital Sander and buffing for working the plates by hand with buffing paddles.

 

For polishing, a hook and loop wax applicator attachment is placed on the sander. It is a 5 inch diameter foam disc, one inch thick. Cut the velvet larger, say 6 inch diameter. It does not need to be sewn or fixed to the foam disc. Downward pressure will keep it in place with practice. You can use double sided tape to hold the plate down on a piece of plate glass. I use a frame or well made from a sheet ABS plastic (8 X 10 X 1/16th inch) adhered to the plate glass with a hole just larger than the plate cut into it, Under the plate is a piece of non-slip padding. I you have something like this set up you will not need to tape the plate in place.

 

Clad plates require about 6 – 12 minutes of polishing. I work in 90 second increments, adding more nushine and mineral sprits at each interval. Discard the velvet frequently. This will remove somewhere between 7 and 10 microns of silver. Clad plates have approximately 25 microns of silver on them.

 

For buffing, before I use the long crowned buffing paddles I clear the surface with a spritz of alcohol and small 3 X 4 inch wood block that is padded and covered with the same velvet.

 

best

 

Mike

 

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[jgmotamedi]

Excellent, thank you Mike.

[rivera1212]

Thanks again mike and Irv

[vjpalsa]

Mike, great post. Can these instructions be used satisfactorily on electroplated plates?

[jgmotamedi]

Don’t use Nushine with electroplated silver, it will cut through the thin layer of silver exposing your base metal. Nushine does work very well to prepare copper or brass for electroplating.

[photolytic]

[Don’t use Nushine with electroplated silver, it will cut through the thin layer of silver exposing your base metal.]

Notwithstanding the excellent Daguerreian credentials of igmotamed; I believe the above quote somewhat overstates the danger here. Good electroplated plates with 25 microns of silver are just as durable as clad plates with a similar silver layer, and even at the current silver price of $30/oz; they are an attractive economical alternative. That being said, silver is silver and it should never be polished with anything suitable for polishing harder metals. While users of NUshine recommend it for polishing silver or gold plated musical instruments, others suggest it is sufficiently abrasive to polish nickel and chrome automobile parts. As always. caution is necessary when polishing Dag plates, regardless of their manufacture.

[jgmotamedi]

Thanks for the kind words about my “credentials.” I agree with you that electroplated silver should be as durable as clad silver, however in my experience it is the rare electroplater who actually puts on 25 microns (1 mil) of silver. My current electroplater, who does an otherwise excellent job, told me that he puts on about .75 mil. It is relatively easy to go through this with Nushine. I know that other electroplaters put on significantly more silver.

[photolytic]

Thanks Jason. Perhaps you need to exercise more control over your silver platers operations. Your contract with him should specify how much silver you expect. Silver is quite heavy so it is relatively easy for you to measure the silver on the plates by weighing your polished copper plates before and after the plating. Stopping out the back of the plates will insure that this silver is definitely on the front of the plates. If you have not already done so you should invest in an accurate digital scale. Its initial cost will be paid back many times during your Daguerreian career. In my last silver plating job the cost of the silver alone was more than $500.

[Mike Robinson]

Hi All,

just reading the above comments and have a few of my own

1.) high current density electroplating done these days with brightened plating baths will create a silver deposit that is significantly harder than my clad silver plates.

2.) 19th Century galvanizing used a much lower current density, (about 250 mA for a full plate. Lower current density = softer, large grained silver deposits.

3.) silver deposits at a constant 4.025 grams per Amp per Hour.

4.) A full plate copper substrate with the verso stopped out would require approximately 10 grams of weight gain to be equal to 25 microns of silver thickness.

5.) At one amp with a single full plate it would require about 2 and a half hours to get 25 microns thick, Most commercial platers work with 3 – 4 amps per square foot of stock that needs to be plated. Plunking three full plates in the bath would still take about two hours work to put on 25 microns on each plate.

6.) I recall Jerry Spagnoli telling me once that his plates have less than 10 microns of silver on them. (a half a mil)

7.) If you remember my original recommendations, I mentioned that using Nushine as directed above removes approximately 7 – 10 microns on a quarter plate.

8.) If you’ve got thin silver on the plate, or reuse it, it doesn’t take long to see copper.

after all this math, my head hurts.

best

Mike

PS a Brand new 19th century clad plate with a “40” hallmark should have about 8 – 10 microns of silver on it before polishing. Last time I checked they were on Backorder at Scovills.

[photolytic]

Thanks for the silver plating info Mike. Take 2 aspirin and call your doctor in the morning.

The Mathematical relationship defining plating is Faraday’s law which can be summarized by:

m = (Q)/F) x (M/z)

where

m is the mass of the metal deposited at an electrode

Q is the total electric charge (electrons) passed through the metal solution.

F = 96,485 mol-1 is the Faraday constant

M is the molar mass of the metal which is 107.88 gm/mol for silver

z is the valency number of ions of the metal ( 1 in the case of silver)

Note that M /z is the same as the equivalent weight of the metal deposited.

For Faraday’s second law, Q, F, and z are constants, so that the larger the value of M / z (equivalent weight) the larger m will be.

In the simple case of constant-current electrolysis, Q (coulombs) = electric current in amps (coulombs/second) x time t (seconds)

For a full plate (area 356.45 cm2), a 25 micron (.0025cm) layer of silver (10.49 gm/cc) weighs 9.348 grams and contains 0.08665 moles of silver.

0.08665 moles when multiplied by Faraday’s constant (96485 Coulombs/mole) will require 8360.5 coulombs or 2.322 amp hours of current or 2.322 hours at 1 amp. The efficiency of silver plating is not 100% but is typically closer to 70% due to other reactions that may also occur in the plating bath. Therefore the actual plating time would be closer to 3.3 hours.

As Mike has noted, modern silver plate is harder that the “galvanized” plate of the 19th Century due to higher current densities and the addition of brighteners to the plating bath.

It should be noted that while the Elkington brothers invented the electro-plating process in 1840, as early as 1847 Elkinton’s workers discovered that by adding carbon disulfide to the silver bath the silver deposit could be made brighter and more coherent. This made electroplated silver suitable for the Daguerreotype process and shortly thereafter electroplated Cristofel plates became available. Carbon disulfide is still used today by some silver platers

Since Daguerreotypists did not need to add any brightener to their plating baths because the “Galvanized” layer was relatively thin, the silver layer on a galvanized plate is not as hard as that of a commercially electroplated plate

[jgmotamedi]

Wow, this is all incredibly helpful. Thank you Mike and John! I am just starting to take plating seriously (previously I just ‘left it to the experts’), and this is all very useful. I guess I have lots of reading to do…

[drdag]

Just as a note. My first plated plates were invoiced to me as approx 23 microns. Recently I have just ‘gone through’to the copper on one plate. I have maybe made 100 images on that plate. I polish just using rouge which is non abrasive. I was pretty impressed by the amount of times it was polished.

[vjpalsa]

I was wondering if someone could advise me as to what I am doing wrong? I am using Mike Robinson’s instructions for polishing and buffing. when I polish with the orbital sander I get a beautiful finish. When I go to the first hand buff with alcohol and velvet I instantly get polishing marks. Any advise would be great appreciated.

[photolytic]

Stop when you get that “beautiful finish”

Don’t use alcohol on the hand buff.

Use a dry buff with dry rouge, then lampblack, and finally no buffing agent.

[vjpalsa]

Thank you for your reply. For the first and second hand buffs do I use a light pressure while polishing? Thank you again.

[fluidrive]

I agree with photolytic, but would mention that Mike’s process recommends a buffing agent and in that case

it is important to clean with mineral spirits,

then soap, then alcohol before hand buffing. I have skipped alcohol as an experiment and now have returned to using it.

soap is almost as important as any of the other steps to remove any micro layer of contamination left by the petroleum based spirits.

that simple step, of cleaning with soap, dogged me for an incredible amount of plates, i can’t even begin to tell you how much this simple element set me back.

use soft flannel or velvet for both the alcohol hand buff and the soap and you will reduce the scale of rubbing marks on the plate. They should be small enough to buff away as suggested.

[vjpalsa]

I have been skipping the alcohol step but will give it another try. I have been using velvet with my buffs but want to know if anyone has any thoughts on velvet versus flannel and if so, what type of flannel would I try?

[newone2010]

Hi Vipalsa and everyone ,

I want to know which kind of flannel too.I am looking for pure cotten white flannel in Chinese internet,but I can not find anyone who sold this.

I just use rouge for buffing.The”rouge”,in China,we call it” iron oxide red”.

I am looking for lamp black too.I already find one guy who sold it.Sometimes,English words can hard to be translated to the correct Chinese words which we called “the thing”.That is often make me confused.I do not know whether some produces are what I think they are.I will purchase the “lamp black”(in china,maybe it is called ” carbon black“.I never know unless I get it.

Good luck!

Li

[photolytic]

Only use flannel as a backing for velvet on the buffing paddle.

Unless you are using it to buff off old images flannel is too rough for polishing.

[vjpalsa]

I just wanted to thank everyone who has helped me get this far. I have a long way to go but here is my first real success. Becquerel method.

 

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