Boxcar Base manual
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.
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.
Most of my plate is printing fine, but one or two areas of the plate are printing heavy. What do I do?
More often than not, this is a result of roller problems. It could be the height of your rollers or your rollers can have an uneven or flat spot on the surface (read more about roller gauges). If you processed your plates yourself, there’s the chance your plate wasn’t processed correctly and you have “fat” text, which can cause some areas to look heavier.
First, figure out why your chase isn’t lying level.
- Possibility 1. Your chase might have cracked some time in the past then was welded to repair it. If this is the case, you may need to file or shave off any excess metal that might interfere with your chase being level.
- Possibility 2. You may have a low spot on your chase. You’ll want to add a shim (a small piece of metal) to the chase to level things off.
In either case, use a professional machinist. They can expertly grind down your chase if needed to create a smooth surface, or they can add a shim to your chase to level things out.
Like our skin, plates can be affected by the room temperature, humidity, and age. When humidity levels are low, the plates can look and feel brittle. With the passage of time, the thinner polymer on the plate edges are pulled towards the denser polymer text and images on the front—this causes curling. With a life expectancy of up to 1 year or more, polymer plates do age, but these simple steps can hydrate your plates and give them extra longevity.
Step 1. Place your plate back in your platemaking washout system for up to ½ a minute (or, if you don’t have a washout unit, simply immerse in water). We suggest room temperature for a quick dunking. A ½ minute may only be necessary if your plates are severely curled.
Step 2. Sponge off the water and place back in the drying oven of the platemaker for 5-10 minutes. If you don’t have a platemaker, use a hair dryer to warm the plate and make it more pliable. Placing your plate in a box and blowing the hair dryer into the box will keep the warm air more contained and warm the plates more effectively.
Step 3. After the plate warms and starts to become more pliable, place the plate in its bag and set a heavy object on it to keep the flattened shape.
This should help your plates relax so you can adhere them to your base for additional print runs.
Here’s some final advice:
- if using a hair dryer, take care to avoid putting it too close to the plates.
- be patient, as warming the plates takes time.
- watch that you don’t handle your letterpress plates too roughly after the wash and during drying so your relief images don’t chip.
- remember to store your plates flat out of direct light and in a bag so that fluctuations in humidity don’t affect the polymer.
- check your adhesive backing, to see if the adhesive needs to be re-applied to the back of your polymer plate for a secure hold on your base.
Photopolymer plates offer an way to letterpress print extremely detailed designs with a deep heavy impression (or a kiss impression if you’re so inclined). The chief problem that new photopolymer users encounter usually deals with roller height/roller condition. But no worries! Unlike larger problems like war or global warming, roller issues do have concrete and relatively easy solutions. We recommend rubber rollers and, if using a platen press, solid trucks. If switching from lead type/magnesium plates, you’ll want to keep a much closer eye on your rollers. You may find our general printing FAQ’s useful, especially if you’ll be using a Boxcar Base.