How Can You Display old Zinc Halftones?

[Jeff]

When old newspapers were operation as you must know they used hot type process intertype and lynotype.

To print a photograph onto their next news paper they used zinc to print onto the news paper.

I have some zincs that are over 40 years old and wish to make frame them together.

My question is what can I use to clean them for some are cyrstilized but still good?

Then I wish to reink them to bring out the definition of the various photo zincs.

What is the type of ink and do I use a roller?

I also wonder if it would do serious damage is I coat them with some form of sealer?

[Alan]

Wonderful idea, to make a display of half-tones!
Suggest consult an industrial chemist; there is probably an inert white powder, which dusted on, then wiped off, leaves white in the etched-out recesses of the half-tone. I do not suggest using baking soda (NaCo3 ?) but (if my memory is correct) that's what the old-time engravers used; it washed out easily with cold water. Perhaps there is an inert paint which could be poured on, and then wiped? Like intaglio, but white. Do only one plate at first, one which would not matter if lost, leave it for a year or more before venturing to others? What do others think? I am  not an expert!                 Alan.

[Dave Hughes]

You make some good points, Alan.

Of course, just blackening the surface won't create the desired effect.

How about painting the surface with a very thin (emulsion type) white paint, then after it has dried blackening the raised areas, before finishing off with some varnish.

You would need some less interesting plates to practice on.

[Mechanic]

Hi Jeff,
One method in the 1960's, of producing copy for offset printing was to photograph the hot metal page. This method was called "Brightype Method". I thought that there might be instructions for preparing halftone plates for photographing and if so it might be of some help to you. I found Ludlow's instruction manual on the internet, URL below. I copied two pages I think may have some useful information.

http://tinyurl.com/6nxlwlr

CLICK IMAGE TO READ

[Derek]

Jeff is slightly wrong in his description of the newspaper printing process: The pages were assembled in a "chase". The elements were: metal type - handset or Ludlow for headings and the text was composed on a Linotype (Monotype wasn't generally used for newspapers, but for magazines and general work) - the pictures, halftones and line drawings, were mostly made of zinc. Proofs were made with linseed oil based ink using white spirit as a solvent to clean the "forme" as the assembled content of the chase was called.
Subsequently the chase was placed under a high pressure press-like device and strong card-like sheet placed over it. An impression of the forme was made. This card-like sheet was called a "flong". The flong was then placed in a device that would curved it and molten lead would be poured onto it to make it into a shape for mounting onto a rotary printing press.
Derek

[Barry Adams]

Just a small correction,

The forme was placed under a hydraulic moulding press, a sheet of flong was placed on and with a with a backing pad all pushed under the moulding press. When the pressure was released the forme would be pushed out and the backing sheets removed the mould made from the flong was removed, a black oily rag rubbed over the back and then the mould would be packed out - strips of a thick very loose paper/card would be pasted into the non printing areas to support them from the weight of metal. The mould would be baked dry and trimmed to size and then into the plate casting machine - in Fleet St  all except the daily Mail and the Express would have been Linotype and Machinery "automatic" plate casting machine running at 4 plates per minute.

[Dave Hughes]

Thanks for that Barry, and welcome back!