Add magnesium carbonate to your ink. Magnesium carbonate is available in our Supplies section from Boxcar Press. Inks are measured by their tackiness or stickiness and their body or how stiff it is. An ink’s body can be drippy like chocolate syrup topping or thicker like frosting or paste. The ink can also be described as being long or short. Long inks are tackier and when pulled up straight from the can will have a long tail. The white powder of magnesium carbonate will stiffen your ink and reduce tackiness.
Oil based inks will dry within a few hours if left unattended on press; dried oil-based inks can take a long time to clean and can even cause rollers to be permanently damaged.
What will I need to do to my platen press before printing with polymer and a Boxcar Base (especially if my printing is blobby and/or has a “halo”)? i.e. how do I add tape to my rails?
Every platen or lever press has wear on the rails and needs tape on the rails to raise the rollers to the right height. This is whether you use lead type or polymer—although the problem surfaces more frequently on polymer if the roller rails aren’t set correctly. You have to build up the rails that the roller trucks travel on so that the rollers just graze the surface of the form. The best way to do this is to add equal layers of masking or strapping tape to each rail. Keep building up the rails in this fashion until whatever you’re printing doesn’t ink up at all (i.e. bring the rollers up just past the point where the rollers ink the plate). Then take off one layer of tape so that the rollers drop down with minimum contact to the plate. This will keep ink from getting on the backing of the plate and the base, and it will also help make your printing crisper. It’s not uncommon to have to add as much as a 1/16″—or sometimes 1/8″—in tape in order to get the rails to the right height. These presses are often 100 years old and have 100 years of wear that you have to overcome. We do not recommend that you adjust your trucks or printing plate/base for this problem. Better printing results from type-high rollers. After you add tape to your rails, we recommend using a roller gauge to perfect the height of your rollers.
Roller gauges are especially indispensable with a platen press. Letterpress rollers need to be positioned just right in order to deposit a thin film of ink onto the surface of the form, without squeezing ink over the edges. A roller gauge will help you accurately measure the height of your rollers so you can produce the crispest printing that your press is capable of. We sell roller gauges, precision ground to type high, which are also very fashionable.
When your rollers are positioned correctly, your printing will look beautifully crisp. But if your rollers aren’t positioned at the right height, your printing will have a halo effect: dark around the edges and/or chunkier/blotchier than it should be. If you ever notice ink on the back of your polymer plate or on your base — it’s a roller gauge emergency! Adjust your rollers now! We have a great video on setting roller gauge height in our Boxcar Training Videos and step by steps are listed here.
Step 1. While your press is inked up, remove the chase (on platen presses) or the base (on a Vandercook).
Step 2. We recommend checking the roller height in the four corners of the press bed. We’ll start in the upper right hand corner. Engage the form rollers and position them over the upper right corner of the bed.
Step 3. You will be pulling a stripe of ink on the round surface of the roller gauge. Pull the gauge underneath the form rollers so that a stripe of ink is transferred to the rounded surface of the gauge’s cylinder. Measure the stripe of the ink: you want your ink stripe to measure 3/32”. If the strip of ink is less than 1/16”, you’ll have difficulty consistently inking your plate (some areas will appear too light, and some areas will appear too dark). If your strip of ink is wider than 3/32”, your rollers put too much pressure on your plate and cause your printing to be chunky/blurry.
Step 4: On a platen press, to adjust the height of your form rollers: add tape to the rails that the roller trucks ride on. You may have to add several layers of tape. Strapping tape or plumber’s silver tape is frequently used for this. If you’re using a press other than a platen press, consult your manual as to how to raise your form rollers.
Step 5: Repeat steps three and four in each corner of your press bed.
Step 6: When your rollers are positioned correctly, you should pull identical 3/32” stripes of ink from the four corners of the press bed, and your printing should be both crisp and beautiful!
If you continue to notice inconsistencies in your inking after adjusting your roller height correctly, you may need to purchase new rollers and, if using a platen press, roller trucks as well.
It’s important to keep the grid on your Boxcar Base clean so you can see its registration marks when printing. If your rollers ever lay ink down directly on the base’s surface, STOP! STOP! STOOOOOOOOOOOOOP! Don’t keep running the press because something is out of alignment. Then ask yourself:
- Are your rollers at type-high? Using a roller gauge, check to make sure your rollers are set for type-high printing material. The surface of the base is far below type high and should never come into contact with the rollers.
- Is your base flat in the press bed? Take a piece of onionskin paper and try to slide it between the base and the press bed – if the onionskin paper fits, one of the corners of your base is working up in the press. Frequently this is caused by tightening the quoins too much. Since the Boxcar Base won’t work up as easily as handset metal type or monotype, you don’t need to tighten the quoins quite as hard.
Still getting ink on your base? If, after checking the roller height and loosening the quoins, you still have problems with ink on your base – contact us and we’ll assist you in problem-solving further.