Copper Plates v. Magnesium

I have some town seals made from copper that i run on letterheads every year, there is a lot of fine detail, but they are starting to show some wear. They have run at least 10 to20000 letterheads since the mid 1950’s every year.. Copper lasts a long time, i mostly use owosso mag dies and have been happy with them. i would only use copper if it was going to be a repeat job with a lot of impressions each time. Dick G.

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I see copper being used for fine detail especially small type on things like business cards. Copper etches differently than magnesium and gives better sloped edges to the image while mag can undercut the image surface and for deep impression work that will cause a less than desireable image. Copper outlasts magnesium, but for shorter runs that doesn’t matter. Magnesium has a tendancy to crush easier than copper in things like blind embossing where there is significant impressional strength being used.

My longest run with wood mounted magnesium was about 90,000 run on a Miehle Vertical, but not deep impression.

For deep impression work, either copper or magnesium mounted on wood presents a couple of basic problems. First is height accuracy because boxing wood made today is fairly inaccurate especially where several pieces are glued together and wood absorbs moisture and individual pieces will expand/contract at different rates. Then under the impression needed for deep work, the wood, or maybe one of the several glued together pieces, can crush, thus destroying the plate and the job. Best results are had from using a patent base like the Sterling honeycomb base using 1/4” thick plates. There are other choices that will work with other bases and thinner plates.

And copper has excellent scrap value. The high end photoengraver for copper is Metal Magic in Phoenix along with Owosso.

this is interesting because I smashed a third of one of my old blocks the other day and posted a question on where to get a duplicate made. Owasso was the name given.

Curious, do they mount on the correct height of wood?
or do you get just the metal plate?

When photoengraving began to be used in the 1800s copper and zinc were the metals used — zinc for cheap line work and copper for longer runs, halftones, etc. So a copper engraving should last longer than a mag plate, and unless it’s really abused weatherwise should not corrode like magnesium. I just ordered some copper linecuts for a project because I anticipate using them over and over.

Bob

pilgrimpress,
Owosso will mount it typehigh or you can get it unmounted.
Anyway you want it.

I have purchased a lot of Magnesium plates from Owosso. All of them have gone bad sitting in a drawer in about a year. A texture forms on all surfaces that makes it unusable when it takes place. My shop is air conditioned and heated. I will only purchase copper for plates I want to save for future use and reserve magnesium for one time use and out.

JF

funny how that works, i’ve bought hundreds of mag. dies over the years, my shop is heated and airconditioned also and i have only lost maybe a dozen plates in 50 years. i store my dies on galleys, if i see that that textured junk is forming on they i simple wipe them off with press wash. dick g.

After using mag dies, I put a piece of chip board over the face and tightly tape it down so not much oxygen can get to it.
Most of my mag dies are reusable.

what is the price of copper vs mag per square inch? ballpark

price,,,Hmmm… depends on if your shop starts on fire. copper is better bang for buck…

I’ve had a lot of really great luck running 16G copper on a “deep relief” boxcar base.

I have to underpack and modify the inking system on whatever press I’m using, because I think the plate comes in a little above type high if I’m not mistaken. Basically I add a piece of tape to the rails on my C&P, take a sheet of packing material out and do a trial impression.

Some doublestick adhesive and crop marks chopped to the edge of the plate allow for precise positioning via the grid, and a plate that can be removed with just a little heat from a hairdryer and some sliding/prying with an aluminum scraper (I use aluminum so I don’t damage the base or the copper plate).

Copper mounted to mag is SUPER expensive, so unless you just want those plates to be ready to go- type high- sitting in a drawer for as long as the MAG lasts- it might be better to look into this method, especially if you already have a deep relief base on hand.