Can I use pre-polished engraver's plates?

[Marizu]

Hello. After a couple of years of procrastination, I have finally picked up a fuming box (thank you, Ismail/polywog) and I need to get some plates.
I was thinking of using what are known as “pre-polished engraver’s plates”.
They come highly polished and have a plastic coating on them that you peel off before use.
Does anybody have any experience with this type of product?
Would they need further polishing before plating?
Speaking to a jeweller friend, he said that it is best to get a large amount of plating done in a single batch to get the unit costs down so I will probably buy quite a few of them.
Thanks in advance for any thoughts that you might have on the matter.

[photolytic]

Yes Marizu,

I have used them for 14 years.

Have the plater put on at least 12.5um (half a mil) of bright silver plating.  25um is even better.

Dull silver plate, used for electrical circuits, or semi-bright silver plate will not polished up correctly.

To save silver put a layer of platers tape, available at MacMaster Carr, on the unpolished side of the copper.

Make sure your plater uses a non-destructive method, such as xray flouresence, to measure the plating so there are no holes in the silver.

If you want to check your silver platers accuracy, weigh the polished copper before and after plating. Correct for the removed plastic film.

Your plater will probably have a minimum charge and will charge a per piece fee for hanging the copper in the bath plus a charge for the silver used.  Thus larger sheets may end up costing you less to plate for the same area but you will have to cut them to size later.

The best of luck

John

[nawagi]

M-

I prepare my engraver’s polished 18 ga. plates in this manner:

I size my plates 1/4″ over the final image size. This allows an area to drill holes for the plater’s wires that I then trim off when they come back – no holes on my shooting plates.

I drill 1/32″ holes at two corners before buffing and use a file to smooth off any burrs at the holes

Remove the plastic covering and mount the plate on a solid surface. I use double sided “carpet” tape.

Get a random orbital sander and make up a pad of thick felt or wool – cheap, worn out wool blankets work well

Mix a slurry of flour-grade pumice and canola oil (any light oil will work – food oils are easier to clean up)

Place a 1/2 dollar sized puddle of this “polish” on the shiny side of the plate. Use the orbital sander with pad to buff the surface in even strokes: I buff 60 seconds left to right, 60 seconds top to bottom, 60 seconds left to right.

The plate should have an even matte finish when the polishing is complete.

Wash and dry the plate carefully. Wrap it in a clean plastic sandwich bag for transport to the plater.

Mistakes I’ve Made:

Wrapping the plate in paper towels and securing the towels with rubber bands – the rubber bands reacted with something and bled through to the copper. After plating these lines came through in images!

Buffed the wrong side of the plate (it looked shiny to me!) – I now label back of all my plates.

Used water instead of oil in the polish slurry. Some operators like water- did not work well for me.

[photolytic]

A matt finish is not necessary for adhesion of the silver plate.

Most platers use an initial high current “strike” coating of silver to insure good adhesion before the main silver electroplating.

It’s good insurance to keep the plastic film on the polished copper to protect it from damage during transport to the plater.

If you send a large copper sheet to the plater only two hanging holes (1/16) are needed.

After the plating only two of your plates will have holes and there will be no waste at the edges between plates.

If you plan your cuts carefully you can usually avoid the corner holes completely and sacrifice only two small quarter inch squares of silver plate per sheet.

[Pobboravsky]

Hi John,

What is the largest plate size that Reliable Plating has done for you? Do you usually get 1/2 mil or thicker?   Does plating surface quality vary from one time to the next?

Your whole-plate daguerreotype — Tunnel View, Yosemite Park — is spectacular!  Clouds in a blue sky – glorious.  Congratulations.

Irv

[photolytic]

HI Irv,

I have Reliable plate 12 x 18 inch sheets because that is the largest size I can cut up with my band saw.

Silver plate thickenss may vary slightly from sheet to sheet but it is alway close to the 1 mil average I request.

Brightness is usually good over the entire area with some slight film near the edges which buffs off easily.

John

[Pobboravsky]

Thanks, John,

Does Reliable test thickness destructively (i.e. by pinholing the plate) if you do not ask them not to do it?

What useful questions did I forget to ask?  Silly me.

Thanks for your help,

Irv

[photolytic]

Irv,

Reliable always uses x-ray Flourescence for silver thickness but I specifically request that they not use pin-holing anyway just to be sure.

Due to a dog bone effect, the silver plate is always thiner in the center of the sheet and thicker at the edges.

I request a minimum of 0.75 um in the center which gives me an average just over 1mil per sheet.

I hope that answers your question.

John

[Pobboravsky]

Thanks, John,

Interesting — the Dog-bone effect is new to me.  That is excellent information.  The plater’s tape must have super adhesion to stay attached during electro cleaning.

As always, you provide the daguerreian community with solid information.  To have a professional chemist who is a skilled daguerreotypist is such a big plus to the cdags community.  You always have been generous in answering questions.  Kudos to you.

 

Irv

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