Polishing ink plate?

It’s situations like this that makes me want to have a lathe. I would try to keep working it down until the finish is smooth, almost polished. (might not have to be that good) Try not to, but if you find that you have taken too much off, which you could do, but not likely depending on how bad the pitting is, you could always shim it from behind so that the rollers make proper contact. And by all mean possible, try to maintain flatness with wood block or something.
I would not recommend any kind of coating, especially enamel.

Sounds to me that the ink plate needs to be shimmed up from the back, as Mr. Jasmund stated. But, I also think you might have a coating on them also. Have you cleaned the rollers, A way to see if the rollers and the ink disk are level would be to ink the plate and rollers as you would to print a job, place a clean sheet of paper between the plate and rollers. Roll the rollers across the plate and see if the ink is even across both side touching the plate and the side touching the rollers.

Another approach would be to use the method used by telescope mirror makers. Get a flat piece of steel at least 1/4 inch thick and maybe half again larger than the ink disc. Get some carborundum powder, maybe #120 or #80, or the kind of paste that’s used to grind engine valves. Using a back-and-forth motion and slowly rotating the disc between strokes, with a little water to make a thin paste of the carborundum between the disc and the plate, grind the ink disc surface against the steel plate. Don’t use the shaft of the ink disc for a handle — that will cause the pressure to tend to tip the disc. Press directly on the disc around the base of the shaft. Don’t let the edge of the disc overhang the edge of the steel plate during a stroke.

Assuming it isn’t too deeply pitted, perhaps 15-20 minutes of this sort of grinding will smooth the surface enough. If you want a higher polish get some 250 grit and work it down with that.

Should work — certainly works with glass!

Bob

I have done just what Bob describes on an ink disk for my Pilot. It was quite rusty, although not deeply pitted. I put a sheet of cold rolled steel (16ga.) on the bed of my little proofing press, put some valve grinding compound on it and started rubbing the ink disk upside down on it until it gleamed like new. I think it ended up flatter than it was when new as I could see the lathe turning marks as I ground it down. I didn’t take any solid metal off, but stopped when all the rust was gone.

I have also used a 2”x6” fine grinding stone to remove rust from a flat surface, renewing the kerosene regularly to wash away the dust. If you are careful and use a random swirl pattern, that can do a good job for you, too.

An ink disc needs to be smooth, but rarely is it fully flat, or need to be.

John Henry

Why would an ink disc need to be shimmed? There are no rails adjacent to it, keeping up the rollers. Won’t the saddle springs pull the rollers into contact with it no matter how far it’s been ground?

Good point modernman! There is only that one place where the trucks leave the rails, but it seems that if it’s too severe the trucks could have the possibility of hanging up on the rails (somewhat) on the way back down…but I suppose it would have to be a severely low ink disc.
Good point however!

Nah. I just checked it. It SEEMS that it would work no matter how low.

[edit] Though no one took issue with it, my mention of a lathe was not for cutting on the disc by any means (although you could); just to spin it to clean it up with an abrasive somehow. I do like Bob’s suggestion and I’ll remember that. I think a lathe would also be good for cleaning dried ink off of a disc as well as rollers; not to mention the ability to make your own trucks and other goodies.

You guys are the best!

I also don’t think a shim will help. The rollers seem to have good connection with the ink bed. I think the ink is just getting stuck in the pits. But, it’s worth trying your test to double check.

I think valve grinding compound will be easier for me to locate, so I will try that technique first and report back.

Thanks a lot.

There’s at least a possibility in my mind that your ink table’s apparent roughness is not your main problem. When I had a 5x8 Kelsey it had an ink table that wasn’t exactly smooth and shiny. I remember a few pit and certainly a pattern of prominent marks in concentric circles from the original machining that I could feel with my fingertips. I don’t have that press any more but I went down to my 8x12 C&P’s ink table. It also isn’t perfectly smooth; with some pitting and one serious ding at the junction of the inner and outer tables (I have the split ink table that was optional…I had it restored to working condition). Certainly a fair bit of ink gets sucked into the gap between the two and the various dings, but I haven’t noticed any semi-circular pattern of light inking. When I had the Kelsey, I had some serious pitting in my composition rollers, and even that didn’t affect my inking all that much. Though as a newbie then I did tend to overink some.

I’d be tempted to check for some sort of contamination on the ink table…maybe that WD-40 you used or high humidity conditions. I’ve seen presses with composition rollers completely refuse to ink up when there is enough humidity in the air. Oil left on rollers can also cause problems.

So what kind of rollers do you have and what are you cleaning them, and the ink table, with?

Thanks Arie - You might be right. I tried some of the tips given in this post and it still isn’t that smooth. My rollers are from Elli Evans in the UK and the material is stated as “modern polyurethane rubber polymer”. I’ve been using kerosine first and finishing with mineral spirits to clean my rollers. Maybe I haven’t cleaned them well enough?

What would you recommend for cleaning?

Kerosene and mineral spirits are common cleaning agents that lots of people swear by. I’ve never used either, preferring the commercial roller wash from NA Graphics. Probably too expensive and/or difficult to ship to the UK, but easy enough to get shipped in the US.

At the university I use Crisco (a solid vegetable oil for baking) followed up by a tiny amount of Simple Green (a water based cleaner and degreaser) only because they won’t let me use the commercial roller wash. Mostly, I think because it smells worse. Though I suppose it is a bit more toxic than vegetable oil.

If these rollers are the dreaded green polyurethane rollers then I’d consider new rollers. I think they came in a few other colors as well. The seem to work fine, but are prone to sudden reversion to a liquid state and will adhere and reharden to everything it touches. And it’s almost impossible to clean up after it’s reverted and rehardened. This happened to me on a Vandercook and luckily I was watching when it started to happen, so I was able to scrape it all off the cores and into a bag before it completely liquified. It was very sudden. Even so some small bits got onto the garage concrete and I was never able to completely erase the marks it left. Scraping with a putty knife followed up with a liberal application of a hand cleaner that has lots of pumice bits in it worked best.

If possible acquire or borrow a second set of rollers (not polyurethane) and see if that eliminates the problem.

I have the related problem of the ink plate on my Kelsey 6 x 10 not spreading ink evenly across the entire plate. The ink collects around the edge of the plate in a 2-inch strip while the center of the ink plate remains relatively ink free. This press is about 20 years old, but was unused until the past month. The ink plate was not rusted or pitted, so I didn’t have that problem. I use rubber rollers. Is there something I am missing in getting the press to ink evenly on the plate? Thanks.

ptclyde, if your rollers are 20 years old that might be your problem, a lot of time rollers will shrink in the middle. Good Luck Dick G.

Thanks dickg, but my rollers are brand new.

ptclyde - I’ve attached a picture of what my ink disc looks like after I try (and try and try) to spread the ink around with a brayer. Attempting to roll it out with the rollers takes too long. Is this what yours looks like?

I can get somewhat consistent ink coverage on the rollers, but it doesn’t last long and I have to re-ink. My images are turning out fairly splotchy, but that could be a combination of things.

splotchy flowers.JPG

ink disc.JPG

amantout—my ink plate is splotchy, too, but around the perimeter the ink coverage is pretty solid—it’s all in a two inch wide strip, with the center looking like the ink plate in your image. I, too, spend lots of time pumping my press to get the rollers to spread the ink evenly, to little avail.

Guys, this isn’t rocket science, but rather basic mechanics and chemistry. I can only think of three variables here: the ink disk, the rollers, and the ink itself. Change one at a time and see what happens. Since you can’t really change the ink disk, try different inks and see if that makes any difference. If yes, then the ink is the problem (or at least part of it). If not, then it almost has to be rollers or the ink disk, so try different rollers, or a brayer as amantout has done. If it’s not (or not entirely) the ink or the rollers, then it has to be the ink disk; probably not the disk itself but something on it. What are you folks cleaning with? Could your cleaner be leaving a thin non-ink-receptive film on the disk? Try cleaning with a different solvent! (Remember, virtually nothing you’d clean with can hurt the disk—try stronger solvent, or isopropyl alcohol, or something.) Any normal printing ink will stick quite well to bare metal, so what’s happening isn’t normal and shouldn’t be happening. Let us know what you find out.

For the press that is inking well around the perimeter, but not well in the center. It sounds like a mechanical problem. It is not likely that the disk is raised around the edge and cupped in the center, but put a good straight edge across in several places. Simple process and it may rule that out very quickly.
My bet, without seeing the patient, is the rollers.
Without ink on the press, make a 1” strip of 20# copy paper as your precision feeler gauge. Place the strip near the edge and roll the rollers over it. Tug the strip to remove it. Do the same in the center of the disk. What have you learned?

One other thing, if the press and ink are in a cold environment this can happen, ink don’t like the cold and won’t spread evenly. Dick G.

Hi,

As the supplier of the rollers mentioned I hope it is OK to contribute.

This problem often occurs after a press has been recently cleaned or restored. The best way forward is to thoroughly clean the ink disc with a vapour degreaser (often sold at computer supplies or car parts stores as electrical contact cleaner) and then leave it overnight in well ventilated space.

Our rollers will be flat and can be checked easily by simply placing them on a sheet of glass. Sometimes when they are new there might be traces of release agent on their surface. This can be easily removed by cleaning them thoroughly. Our recommended method can be found in the FAQs section: www.ellievans.myshopify.com

The modern material we cover our rollers does not suddenly turn into liquid. Our rollers last ten years and give excellent print quality throughout this time. After ten years the material will begin to soften, the printer then has a few months in which change the rollers before the material stops functioning. Even at this stage the material does no turn into liquid. Only if all these signs are ignored and more months pass will the material start to degrade.

Compared to the average life expectancy of 2-3 years for composition rollers and 5-6 years for standard rubber rollers, our polyurethane rollers offer the letterpress user an excellent choice. Ten years of service, no shrinkage, unaffected by humidity, no gradual hardening of the surface and natural tack.

After thirty years of working in the rubber roller trade, I am confident our polyurethane rollers are one of the best products available to letterpress users. Anyway, if you are still having trouble with your press, please don’t hesitate to contact us: [email protected]