✅ SOLVED Copper Etchings / Printing Plates - Cleaning After Digging Up

[randazzo1]

Hi all --- We've been digging at a new site in central NJ. The site had a house on it built circa 1850. All that is left is the foundation and a few pads from outbuildings. We've turned up one 185? seated half dime and a few pieces of 1900's silver as well as the usual assortment of trash and clad coins. I was last out there yesterday (power is out and there is no gasoline to be had anywhere here --- so there isn't much to do!). We found about a dozen of these square copper plates that we originally mistook for electrical junction covers or something of the like. They are however some sort of printing plate or etching plate. The largest is about 4x4 and the smallest 1.5x1.5 (inches).

The ones we can actually see all depict dogs. I am wondering what era they are from and what exactly they are for - newspapers? books? Also - it would be nice to know how to use them. Finally, and perhaps most importantly - we are trying to figure out what the presence of these things means for the site --- was this a common item to have in household at some point? I am totally unfamiliar with these types of items.

We figured out a pretty good method for cleaning them for anyone who is interested. The first one I scrubbed with a brush and then a sponge. This technique destroys the delicate copper cells. The next one we put in an ultrasonic clock cleaner for about 1/2 hour. Not much of a result. We experimented with varying solutions of nitric and hydrochloric acid. Best result is one table spoon of hcl in about 2 cups water. Add the solution to a pan and cook the plate for about 1 minute on high heat (I don't know if this is safe so do it at your own risk@!@!).

Posted below are photos of some of the plates and before and afters of the cleaning.

Thanks in advance for any advice anyone has on what they are, how to use them, and what they were used for.

 

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[mtholen]

Those are cool and unique

 

[capt-zero]

I'll try to give you a quick rundown, but it's a somewhat complicated procedure that has a long and lustrous history, so you might want to do some surfing on the subject of printing and engravings yourself. Prior to the discovery of lithography, which was invented in the late 18th century and became widely used only after the civil war, etching and engraving through the use of copper and steel plates was the most economical way to produce identical images on paper in large numbers. The process was used in the printing industry extensively from the mid 16th to the early 19th century and is still favored today by many artists. This is the method that artists such as Albrecht Durer, Rembrandt and Francisco deGoya became famous. In fact, it wasn't until the 19th century that Rembrandt became known as an accomplished painter at all, during his lifetime he was known,largely, only for his etchings. Etching opened up the world of fine art to the common individual and even the poor and middle class could afford original works to adorn their walls.
The process of heliogravure, also known as photogravure, was discovered in the late 19th century, and for economic reasons became immediately popular with the printing industry. Similar in look to copper plate engraving, it uses a photographic process to transfer chemicals onto and etch a copper plate, instead of the tedious process of engraving or acid etching the image to the plate by hand. The end product is quite similar and difficult to distinguish without experience.
To transfer the images of etchings, requires first inking the plates, then after a very good wiping off of the excess ink, placing the plate in a special press along with damp printing paper so that the pressure of the press forces the remaining ink out onto the paper and this process also leaves a distinctive plate mark on the paper. A mark used by collectors to help identify genuine etchings. To transfer images from photogravures is the same, but does not leave the same quantity of ink on the finished work, which is how the two are distinguished from each other. Anyone who decides to take up collecting engravings should learn how to tell the difference.

On the plates you have shown I cannot tell from the first three photos, and really can't tell without holding any of them in my hands, but the last photo does appear to be a photogravure plate. There are several printmaking forums on the web if you search for them, they can give you lots more, and probably more accurate information than I can give you here.

What is disapointing, to a collector, is that the plates probably have less value than the finished prints. This is most likely due to the problem of properly displaying them. Great find and good luck.

 

[randazzo1]

Thanks Captain Zero -- that is more info then I could have hoped for. I followed your advice and looked into it and you are right-on -- they are phtogravure plates. We're going to go back out on the weekend and get some more of them. Thanks again.

Thanks Mtholen - I think so too.