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Troubleshooting Laser Sublimation

Reprinted from the March 2003 issue of The Engraver's Journal. By Richard Hilton. All rights reserved.

Whether the cause of your laser sublimation headaches is something you're doing wrong or an equipment malfunction, getting to the root of the problem is as satisfying as it is worthwhile.

In some activities, you can follow and exact set of steps and get an exact result every time. Sublimation isn't quite like that. Sublimation dyes change with age, and toner cartridges can change during use. In approaching laser sublimation, it is better to understand the basic principles than to remember a recipe or a set of rules.

If you watch someone doing laser sublimation, you'll notice that it looks extremely easy and trouble-free. And, in reality it is easy - until some variable changes.This guide to troubleshooting for laser sublimation is aimed at addressing the common problems by explaining the underlying principles.

“It’s All Fuzzy!”

The most common problem with laser sublimation is an image that has fuzzy edges instead of crisp, sharp definition. This problem has given laser sublimation a bad name among demanding professionals who insist on the highest quality products. I hear it again and again from people who have never even tried laser sublimation. “Laser sublimation is too fuzzy for me.” That’s like saying, “Fords drive too fast for me.” Fuzziness is something that can be controlled easily.

In laser sublimation, you make an image on ordinary paper using a special toner cartridge and a laser printer. The paper is pressed against a substrate, usually metal, in a heat press at around 400F. The process of sublimation actually begins at a much lower temperature, just under 300F, and extra heat acts exactly the same as extra time. In other words, you’ll the same results at 350F for 30 seconds as you would at 400F for 13 seconds, as and example.

An image that is “undercooked” has a purple cast and unfilled characters. It isn’t all there. “Overcooking” yields fuzziness. The printed image on the paper has dyes that move over to the metal surface. If you don’t remove the heat in time, the dyes keep coming and they mushroom out from the edges of the image.

In sublimation you have a gradient scale going from weak and purple to fuzzy. In the middle is a very nice, crisp, dark image.

When an image is fuzzy, the first question has to be. “Do you press through the plastic?”

Plastic On Or Plastic OFF?

In laser sublimation, you have an option of removing the protective plastic from the metal surface or sublimation through the plastic and removing it after heat pressing the plate. If you remove the plastic first, you will need to clean off the image with a citrus cleaner, because a toner residue is left on the plate. If you sublimate through the plastic, no cleanup is needed.

Many shops press through the plastic because it’s so much faster. You simply wait a minute for the plate to cool and then peel off the transfer paper (with the plastic melted into it) and the plate is ready to use.

Other award-makers are absolutely certain that pressing through the plastic makes an inferior product. Sometimes when I ask the question, “Plastic on or plastic off?” I get a reaction as if I had insulted the person’s spouse. Often I hear, ”My customers deserve better than that!” Recently I spoke to a woman who has been doing sublimation since the early, early days. And she had been having difficulty getting a large reverse (black area) to fill in uniformly. She had tried everything – density settings, times and temperatures, everything. But when I suggested that she just try leaving the plastic on, she became upset at a mere suggestion.

The real story is that a very, very good image can be produced when pressing through the plastic. It just takes a little trail and error to find your best times and temperatures Those settings may change during the life of a toner cartridge, and they certainly have to be reviewed when a new cartridge is installed to maintain the highest quality.

Fuzziness is a result of too much time or temperature in pressing. This fact is true weather you leave the plastic or take it off. But taking the plastic off gives you a wider latitude of time and temperature. Times do not have to be nearly as exact with the plastic off.

One family of toner cartridges has and optimum pressing at 400F for 13 seconds, with plastic on. It will begin to show fuzziness at 15 or 16 seconds. With plastic off, It presses well from 11 seconds up to 40 seconds. If someone were to try pressing with or without plastic for, say, 30 seconds, one example would look sharp and the other would look fuzzy. So most people would conclude, quite wrongly, that leaving the plastic on yields image fuzziness.

Since 13 to 15 seconds is such a narrow margin for an acceptable product, you might choose to dial the temperature back to 350F and push time up to 20 to 35 seconds. But how do you find the optimum settings for your current toner cartridge and your heat press? You deliberately overcook and undercook the same image, and then aim for the middle. It may take six or even eight test pressing to find a really good time/temperature combination.

“It’s All Purple!”

Purple is the color of undercooking. A black image will be weak and purple-toned if it doesn’t get enough time or temperature. This is not the same as the deep reddish cast a black image will show when it’s first removed from the press. An undercooked metal plate will have a purple color where there should be black, and areas will look washed out. The solution is to increase time or temperature.

“It Has Random Background Spots!”

Random spots will be visible both on the printed page and on the metal.

“The Solid Areas Are Weak!”

All laser printers have difficulty printing large solid areas. It has to do with the drum's inability to recover to a full electrical charge in one revolution after having been completely discharged. Generally, You will achieve the best solids in the top third of the page, when the drum is on its first revolution. If you try to print a full page of black, you will be disappointed with almost any printer and almost any cartridge. Usually, you will see the lower two thirds of the page much lighter than the top third, and all edges will be much darker than the center and you will probably have some bands of dark or light going both horizontally and vertically. Some cartridges will print full solids better than others, and if sublimation heavy solids is important to you, you probably should discuss this with your cartridge manufacturer before ordering. But don't expect miracles; a full page of dense solid is beyond any desktop laser printer.

“Solids & Halftone Areas Are Full Of Stripes & Plaids!”

Solids and halftones show off the very worst of any toner cartridge. The drum, the magnetic roller and the charging roller all develop usage patterns, starting with the first print of a new cartridge. After a few hundred pages, the patterns will be visible in a halftone or solid. Some cartridge manufacturers use only new cartridges , and change out the regular toner for sublimation toner. Other cartridge manufacturers start with used cartridges and install new components, like the drum, magnetic roller, charge roller and cleaning blades. Changing the components allows the manufacturer greater flexibility in fine-tuning the end product since there is a wide spectrum of replacement components available. But a manufacturer who reuses old components will produce cartridges that start off with stripes and plaids an get progressively worse.

“A Mark Repeats Down The Page!”

A repeating mark may be in the cartridge, or it may be in the printer. Find another cartridge, or it may be in the printer. Find another cartridge, even an old, ”empty” one. If you get the exact same mark with two different cartridges, the printer is at fault. Most likely, the mark is on a fuser roller and fusing assembly needs to be replaced. Call a local repair service.

If the mark goes away with a different cartridge, then the cartridge is at fault. A repeating mark can be caused by some flaw on the drum of the cartridge, fresh out the box, and it prints a repeating mark down the page, call your cartridge manufacturer.

If this is a new problem with a cartridge you've had for a while, the cartridge manufacturer may not be at fault. It is very easy to ding a drum or leave some mark on its surface. Call your cartridge manufacturer and discuss the problem. If that doesn't do it, examine the drum for yourself. Flip the cartridge over on the table and find the shutter. This is a piece of plastic that springs back and exposes the drum. Open it up and inspect the surface of the drum, looking for any imperfections shaped like the mark on the page. To one side of the drum you'll find a plastic drive gear that will rotate the drum. It is very important to rotate the drum only in the direction it normally rotates in the printer. This may take a few minutes to figure out, but rotating the wrong direction will ruin the cartridge no matter what else is wrong with it. So if you have to rotate the drum, be sure of the correct direction.

Some marks on drum are little surface pieces of dirt or gunk that can be cleaned off without damaging the drum. If you find a mark, try cleaning it with a dry, clean cloth. Do not use alcohol or water on the drum.

“The Image Just Fades Away!”

This is a characteristic of old sublimation toner. The image has a brown cast, is weak and can be washed away with citrus cleaner to almost nothing. It fades in direct sunlight to a pale hint of an image. Sublimation toner that has been on a shelf for about two years can get this way. If you get a cartridge like that out the box, send it back. If you let a cartridge sit on a shelf for several years, you can expect it to be deteriorate without being used. Buy only the number of cartridges you can use within one year.

Emergency Repair For HP 4 Or HP 5 Cartridges

The cartridge which is used in an HP LaserJet 4 or 5 is easily divided into halves. One half contains the toner and the magnetic roller. The other half contains the drum and charging roller. If you have a cartridge that is not working right, you can swap the toner half of the malfunctioning cartridge with a drum half of an old spare cartridge. Example: A customer called saying that an old green cartridge (not mine) was streaking and producing very ugly prints. I talked him through removing the toner half of the green cartridge and attaching it to the drum half of an empty black cartridge. This produced excellent quality green plates. I didn't get a sale from the call, but the customer was able to get a job out on time. And he'll call back.

The procedure is simple. All you need is a Phillips head screwdriver. Lay the cartridges on a cushioned, flat surface. Locate the clips that hold the two halves together and remove the screws holding in the clips. Pull the clips out and the cartridge will open up (neatly) into two halves. Swap the two halves and see if this helps your problem. Since some problems come from the toner side, swapping out the drum side doesn't cure everything. But it does work in many cases.

Other cartridges don't come apart that easily, and some cartridges are extremely messy to open up. Don't try opening other cartridges on your dining room table.

It's always a good idea to keep a backup cartridge on hand. This can be a used cartridge that isn't quite empty, or, if you'll use it within a year, a new cartridge kept in its box ready for use. Things happen to toner cartridges, even during normal use, and it's always advisable to keep some kind of a spare on hand. You don't drive around without a spare tire, do you?

Weather the cause of your laser sublimation headaches is something you're doing wrong or an equipment malfunction, getting to the root of the problem is as satisfying as it is worthwhile. Few things are as frustrating as repeatedly encountering problems in the supposedly “easy” process of sublimation. On the other hand, few experiences are as satisfying as hearing the “oohs” and “ahs” of a thoroughly pleased customer as he picks up his picture-perfect job once you have mastered the fine points of laser sublimation, perhaps with the help of this article.