SP20 Slurring

I’m at wits end trying to figure out why I’m getting slurring problems on my SP20. I’m using photopolymer plates from Boxcar on a patmag base. Everything calipers out correctly to .918, including my roller height gauge. I’ve adjusted the rollers and measured them in several places on the bed. I have brand new rollers from Pamarco. I’m using an oil-based mix of trans-white, 072 and Black (cool gray 7). I’m printing a large form (10×15, lots of text) on 110 lb Lettra. I’m just not sure how to proceed to fix this. Help, please!

11 thoughts on “SP20 Slurring

  1. Jonathan Selikoff - August 1, 2011

    I ran another job today. The base ink was VERY loose, so I put a fair amount of corn starch into it (no mag carb on hand yet) and I had no slurring. I’d say the corn starch did shift the color slightly, but I lived with it.

    I also took a q-tip to the gear racks along the bed to clean them out, which may or may not have helped. Not a ton of gunk, but gunk nonetheless.

    Thanks again to the great printers out there willing to share their advice (and also to Paul for providing this forum).

  2. Gerald Lange - August 1, 2011


    Don’t discount what others have said here. I teach a few courses a week and I’m getting pretty good at knowing what is wrong every time I walk into these kind of messes. Not always, but most of the time. Plus, I’ve been printing on Vandercooks for about 36 years, which is, quite frankly, far too long.

    I personally only use printmaker’s stone litho inks so I can’t really comment on other kinds of inks, except to say they are basically s**t.

    I’m not trying to be a smart ass. Try the opaque, use the magnesium carbonate. Get the ink to a stiffness where you can draw in it with your knife and it holds, and it will not run down the knife whatsoever.

    That will help, along with correct roller height, correct impression (packing materials), etc. Assuming the press and rollers are in optimal condition, etc.

    SP20s are a little, um, problematic. A bit under built for their size.

    Good luck to you.


  3. Jonathan Selikoff - July 31, 2011


    What would you use to mix a light colored ink? I was mixing Cool Gray 7, which called for more than 90% transparent white? I was going to try opaque white but it was as thin as the trans-white in consistency, so I just decided to try to thicken up what I had already mixed. I’ve had slurring with some other, pre-mixed, colors, but the consistency was also somewhat thin. I would be so relieved to know this is mostly an ink problem.

  4. Gerald Lange - July 31, 2011

    This seems an inking issue. The OP mentions using a trans-white mix. Not something I would use for printing type. Ever.


  5. Alex Brooks - July 29, 2011

    I would reiterate 3 issues that Ray and Paul have noted.

    Vandercooks like really stiff ink, especially when you want fine detail like small type or wood engravings. On my wood engravings I use intaglio ink which has to be worked up on an ink slab because is was so stiff.

    Often if the rollers are set minutely too low they will wipe ink off of the leading edge of your form, leaving a halo on the shoulder.

    And if your paper is moving around at all, it can cause this sort of thing. I often print with a sheet that is too long (or work & turn), so I can keep an even pressure throughout the printing cycle, and then trim the paper after printing.

    good luck, Alex Brooks

  6. Paul Moxon, Moderator - July 29, 2011

    Great photo. Does this slur happen at the first line of every new paragraph?

    Are you running the sheet with the grain parallel with the bearers? If you have them, try using the star wheels and the friction fingers to hold the sheet down as it passes over the form. Otherwise, try taping the end of the sheet to the cylinder. Use a removable tape like 3M’s 811 Scotch Brand. It’s time consuming and annoying, but could help.

    The fingers, which are made of phenolic and likely broken, are mounted on the bottom front tie rod. See the manual, Sheet 243.

  7. Jonathan Selikoff - July 29, 2011

    Thanks, Ray, for the detailed suggestions. Regarding printing the lines parallel vs. perpendicular, I was getting the slur both ways. The sample I showed above was, obviously, with them parallel. When printing perpendicular, though, I was having trouble maintaining consistent ink coverage (i.e. heavier at the start and lighter at the end). I assume this is ink starvation, probably from not enough ink on the press, but I’m open to other ideas.

    The corn starch did seem to help a little, but I’ll get some mag carbonate. Trans white is a particularly runny ink.

    I couldn’t use roller bearers in this instance b/c the sheet size was 19″ wide on the press. I’ve tried them in the past with no luck. This was before I had the new rollers.

    The base and bed are clean. I also go for about a nickel width on the gauge, which is what I was getting. The ink color was very light, so I admit it was hard to tell, but I’ve also gotten somewhat sensitive to how the gauge feels as it’s pulled under the roller, so I don’t think I was too low. One thing I haven’t gotten clear on: I can raise the rollers above type high (according to the gauge, which I’ve checked with calipers) and they still ink the form. Why is this?

    I’ll run some more tests next week. I can’t tell if this is just relative beginner’s problems or something more of an issue with the settings of the press – cylinder bearings, etc.

  8. Ray Nichols - July 29, 2011

    Corn starch is too roughly ground.

    We got our magnesium carbonate at Daniel Smith.


  9. Ray Nichols - July 29, 2011

    Couple of issues.

    I suspect you are printing the type with the lines of type parallel to the rollers. You would rather print with them perpendicular, if possible. The rollers MIGHT be dropping down a bit as it crosses into that extra space above the ‘commitment’ line and then when it hits the ‘commitment’ line there is too much pressure. When it pushes down ink has been pushed onto the side of the type so when the paper contacts the very edge of the paper it is pulling some extra ink from the edge of the type and you get the halo.

    I think the problem is that you’ve got the rollers too low. When you say the roller gauge was used, how wide of a line does it make on the gauge. I make it the width of a nickel.

    Other possibilities.

    Ink its too thin. It has been hot here and the ink can be quite thin. Use some magnesium carbonate in it. You should by it from a store that sells printmaking supplies so you can get the really finely ground version and not the stuff from a sporting goods store. More expensive, but it works better.

    Could be worth trying roller bearers along the sides. I’ve even done things like put some thin tape right at the problem areas to actually lift the rollers even more.

    I don’t think this is your problem but be sure to clean the bottom of your ‘base’ and top of the press bed. Also under the 0.050 sheet if your Vandercook has that. And the rails.

    . . .

    Often you will see this on the first line where the inking rollers hit. Then they will roll up on them and it will be OK until the rollers are allowed to drop back down (we are talking thousands of an inch here) where it will hit hard again. You see this when you are printing with the type sideways and one line is longer than the others. The type will ‘heavy up’ when the rollers are over just a single line or two but will do Ok when they are over a paragraph.

    I vote roller height. Make it the least to get ink on the plate and work downward. Make adjustments 5 times with prints in between and I bet you’ll get it to work.

    . . .

    Also, once you’ve gotten the ink on the sides of the type you have to clean the plate before any of this will work. If you adjust the roller height you need to clean the polymer plate before printing.

  10. Jonathan Selikoff - July 28, 2011

    Let’s see if this works. An iPhone pic through a loupe!

    You can see the slur in the word “commitment.” It’s not as bad there as some others. I did tighten up the drawsheet (tympan only, no mylar). Impressions is fairly minimal – no show-through to the other side and certainly no resistance. I also added some corn starch to the ink to see if that might help. It did a little.

    The slur wasn’t consistent through the whole print. I’d notice, over the 15″ length, it would be most pronounced in the middle. It also seemed to get worse if I double-rolled sometimes.

  11. Paul Moxon, Moderator - July 28, 2011

    A photo might help, but I suspect that your drawsheet is not tight enough. If there is a ripple then it is not laying flat against the cylinder. Loosen the reel rod, adjust the drawsheet and rewind its tail as needed. Shifting the reel rod laterally should eliminate any remaining slack. The side to side play is designed to compensate for this very issue. Are you using Mylar as a drawsheet?

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