Any hope for corroded blocks?

I stumbled upon 2 sets of this 3 colour block set at Newark Antique Fair (still in paper & string wrapping). They do unfortunately have an amount of corrosion (white clouds) on them. Is there any hope to save these blocks (please dont fall off your chair but should I say the words - wet & dry paper? … ***crashhh***)

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Those don’t look too bad.
Go at them with a dry toothbrush to see what that will do. A brass type brush would be good, but you don’t have one.
If the dry brush does not clean them up, then use some toothpaste, rinse and dry.
Wet and dry emery paper or crocus cloth only as last resort.

If you decide to use wet/dry paper, get at least 300 or 400 grit, the finest you can find, lay the sheet on the stone or another dead-flat surface, and work the blocks gently face down on the paper. That will lessen the chances of causing a height difference, since I assume you plan to print them.


Sand the face? By hand? You’re joking….right?!

Nope. I’ve done it on smaller blocks, even a couple of mags. It’s that or the block is unprintable. I can’t see these well enough to tell if they’re that bad. You’re basically just removing the resist, which the corrosion has already done.

It’s not a matter of just removing the ‘resist’. The corrosion has already undercut (if)any existing acid resist. Should you view a corroded cut through a glass, you would note the lines resemble the Sawtooth Mountains. The pressure from even a light printing will just crumble the lines. And, using a coarse (3-4c)silicon carbide paper, utilizing uneven hand pressures at best, simply exacerbates that condition. Your approach is akin to using a wood rasp on a fine oak table top. Will the ‘sanded’ image print? Probably. But, I suppose if line thickening/obliteration and trap loss is ‘good enough’, well, have at it.
The ‘bloom’ situation though should serve as cautionary tale for many. Don’t wrap type in paper - chemical free or not - for any extended period; do not lock-up a form having brass border; and keep humidity under control in your shop. For those in high humidity areas, take a page from local welders and treat your more valuable faces to an oven. Oh, yes, and after handling said ‘bloom’ - don’t lick your fingers. :o)

Try a 1500 grit sandpaper. Most hardware stores carry it now. A 400 grit will take off too much metal, too fast, and leave scratches that are noticeable. As you push a cross the sandpaper the front edge of the block will want to dig in and can easily become rounded. You have to use extreme care doing this, because you can’t put the metal back once it’s taken off. Use removable spray adhesive and a piece of thick tempered glass as a surface so there is as little give to the surface as possible. It will widen lines, so be aware that the cut will never be quite the same, and the oxidation on the shoulders can’t be properly removed, so it is just a stop-gap measure - not a sure cure.

All the above and try and get a pull off each colour in blacvk on its own. Scan and have photopolymer plates produced. My experience with this corrosion which can be in type as well isn’t really reversible. Who knows really how it starts.

Corrosion is oxidation of the metal, so areas of metal have been turned into rust here. The bits of metal are now gone and left pits in the printing surface. You can try to smooth the surface with fine abrasive paper but to get a smooth surface you would have to remove enough of the actual image metal to get to a flat surface that you may well be able to see plainly that lines are thicker when you print it. Another method is to remove any trace of resist and then wash the surface with a weak acid solution which in theory would remove some surface metal and smooth it out, and since there is no resist the acid would also remove metal from the edge of each line keeping lines thin. The type of acid would correspond to the type of metal. This method could easily backfire too if the edges of the lines got a jagged look.
What ever method of conservation you choose, the cut has been damaged and will likely never print the same as it did before the damage. The quickest option is abrasive paper but the best approach may be to save the original as is, recreate the art and make a new cut.

wow thank you everyone. Some great ideas and advice. I will take a print as soon as I can before approaching them then try with the gentle brush method moving on towards abrasives as a last resort. Any other pastes to use with a brush as well as toothpaste? (like a cutting compound like T cut?)

Finally got a proof press and printed this plate:

Mick, the rubber litho sheet is really handy, thanks again!

On corrosion I have used electrolysis and a nylon brush. immerse the part in a water solution with a dash of baking or washing soda and attach the negative terminal of a battery to the part and the positive terminal to a waste part and dip that in the solution. Make sure the parts don’t touch. You will see bubbles forming on the parts, depending on the level of corrosion, a few hours to a few days will do it. Remove from the solution and brush with a stiff nylon brush. With mounted cuts it is a little more difficult, the cut would have to be removed by drilling out the nails. David

I use a block of charcoal, available at art supply stores. It is square, and has large flat face that when rubbed over the cut, is still gentle, but abrasive enough to take it down.

I have recently come into ownership of a number of cabinets of metal type and have a similar situation as above. There is some oxidation as per the photo.

I don’t really think going over every single piece of type with a brush to remove the rust is a viable solution here. So that leaves me with either:

a) electrolysis; or
b) lemon juice and vinegar

I’m tempted to go with lemon juice and vinegar, because i’ve found the results when using this technique on parts of the press to be great, but the problem is, the smell!! It sticks around for ever.

Also, when I was restoring my HS3 I just oiled up the parts that had been soaking after they were rust free to give them some protection, but obviously, this wouldn’t work with type because the last thing i want them to be is oily.

Whats the best way to ‘clean up’ after soaking them if i decide to go with the lemon juice option for parts that I don’t want to get oily?

Has anyone embarked on a large scale cleaning job like this before that could offer some advice?

image: oxidised_type.jpg


Ah the lovely smell and bubbly grey gunge of Adana H/S 2 soft metal parts in lemon juice, if you left them in too long.

Not sure why you are using vinegar and lemon juice.

I’ve just spent some time soaking palace script in lemon juice and had to brush every piece with a tooth brush. I found a number of pieces of type had small pits afterwards and if I left them in to soak for too long whatever was on them hardened.

What do you think is a good guide for an appropriate amount of time to soak? When I de-rusted larger metal parts on my Adana I left them in overnight, but i get the feeling that cleaning small metal type this is maybe excessive?

Wouldn’t want to damage anything.

So you recommend just lemon juice, no vinegar for these? And then just brush them and dry them off after soaking?


For the ‘instant-is-everything’ crowd, employ an ultrasonic cleaner when cleaning type pieces. The machines are inexpensive, usually employ a non-corrosive medium, and the ‘bubble’ action lifts encrusted ink with ease. Failing that approach, simply use a mild household cleanser (Mr. Clean, et al) and toothbrush. Sure it is slow - but then again so is letterpress. :o)

Ben: it looks a bit like type blight.
Search the discussion forum for it.