Cleaning halftone cuts

I am sure this has been discussed before. however a search revealed nothing in the archives. I have hundreds of these halftone cuts, some look to be copper, others maybe zinc. I have a lot of historical buildings and people and would like the best solution to get them as clean as possible. I have tried Naptha, Acetone, blanket wash, nothing seems to really do the trick. Anyone have a suggestion?
Thanks in advance for your responses.

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Best is to start with the least aggressive chemicals and work your way upward. You’ve already got Naptha & Acetone checked off the list. Next I’d try come carburetor cleaner and then move to paint stripper. Let it sit in the paint stripper and then wipe off what you can….and keep repeating until it’s all clean. Depending on the level of paint stripper and thickness/hardness of the ink will depend on how much it will remove each time. Take your time, let the chemicals do the work. DO NOT use a puddy knife or anything more than a nylon tooth brush!!! You don’t want to damage the soft metal which will effect your print!!!

What’s on them? If it’s dried ink then the various solvents described above. If it’s corrosion then you have a different kind of issue. It’s not just going to wash off. The issue of corrosion on letterpress cuts has been disscussed many times here with many different suggestions and is a very common problem.

I would also recommend picking up a black horse hair brush. In our opinion, there is nothing better for wicking out ink from the recessed surfaces, and cleaning up detail once any ink is taken care of chemically.

I have done what you are trying to do. I used numbering machine cleaner, it worked well with a firm natural hair brush to lift the dirt and ink out of the halftones.

Sometimes printers would protect and store their blacks after applying a thin layer of ‘liquid ground’ or ‘liquid tar’. That can be removed with a cloth and kerosine.

‘blocks’ and not ‘blacks’…

Do you want to clean them to make them look nice, or to make them print better? I’m guessing you want to print with them.

Assuming they are not corroded, and assuming that they were washed by a competent tradesperson after their last use, they may print ok the way they are, with just a normal once-over with printer’s wash and a brush as you would do at the start of any job.

Have you tried to print any of them? That would be what I would do first. It would be unlikely that several hundred cuts would have been put away in an unusable condition. The whole idea of keeping them would have been to use them for repeat orders.

If, however, their last user left them with ink on them from the press without washing them, then yes you would need to do some of the things mentioned above.