Although Hewlett-Packard does not recommend refilling their disposable DeskJet/DeskWriter cartridges, there is little risk and much profit in refilling your own model 51608A or 51626A print cartridges. The HP DeskJet/DeskWriter color cartridge 51625 is not refillable. HP made this happen by not putting vent holes in the top of the color cartridge. Over the course of three years experimentation, the following helpful hints should save pain for the neophyte user who plans to refill cartridges.
Use only water-based ink, as alcohol-based inks will immediately dry up and clog the print head. Previously, the Parker "Super Quink" brand was the ink of choice for veteran cartridge refillers, but Parker no longer produces it. The remaining Parker ink, known simply as "Quink," will not provide good results. The best current brand for refills is known as "Skrip." Found in a yellow box, this is an extremely common brand of office ink generally used for stamp pads and fountain pens. You'll get the best results from the permanent black ink, but colored inks such as blue and red work fine too. When experimenting with a brand, keep in mind that price is no indicator of performance.
You can refill the cartridges using an ordinary 3 cc diabetic syringe, available at most pharmacies for less than 50 cents. (In North Carolina, U.S., no permits or prescriptions are required to purchase these syringes, however that may not be true in other states or countries.) Wash out the needle with warm tap water and you can reuse it almost indefinitely. Start-up costs for your homemade refill kit should run less than $3: about $2 for the ink and less than $1 for the syringe. You can get 11 refills from a single 2-3 ounce bottle of ink at a cost of less than 20 cents per refill!
Don't refill a cartridge that has sat empty. Refill cartridges immediately after they run out of ink. It does no good to wait and collect used cartridges because remnants of the original ink will dry up and render the unit worthless.
To refill the cartridge, assemble the ink container, cartridge, syringe and a few absorbent paper towels on your work surface. Do your work on a glass-topped or ceramic surface which will not absorb any ink spills, and be sure to place a paper towel under the cartridge. Don't pour the ink into the top of the syringe; instead, immerse the tip into the inkwell and withdraw the plunger, sucking the ink into the cylinder. Plunge the syringe into the top of the cartridge, through the vent hole for the entire length of the needle and slowly press the plunger. If you see ink bubbles around the hole, don't let them pop, as the ink will splash everywhere. Hold a clean paper towel around the vent hole to catch the bubbles. One cartridge will hold two injections of ink from a 3 cc syringe.
Wipe off the print head. You should have some leakage from the refill process, which indicates a successful refill. If you see no leakage, the print head may be clogged. It's possible to unclog the head by blowing into the vent hole (carefully!) or wiping off the print head with a wet paper towel. You know the refill worked if you can wipe the print head with a tissue or paper towel and get a thick band of ink on the paper.
Using the right kind of printer paper with your refilled cartridges will provide better-than-new results. Use a paper with high cotton content and a tight fiber "weave." Hammermill Bond, Hammermill Laser Copy, St. Croix Laser/Xerographic, and Xerox 4240 provide great looking printouts from any cartridges, refilled or not. Refilled units also work fine with transparencies.
You can refill the HP 51608A up to ten times before the electrical contacts on the cartridge begin to deteriorate. I have used refilled cartridges in the same DeskWriter for the past three years with no damage to the printer.
Refilled and new cartridges should be good for about 500 pages of printing text or light graphics. If your printer gives less than 200 pages from a cartridge, there is an upgrade kit available only to early purchasers of the DeskJet and DeskWriter that greatly extends the print life of any cartridge, refilled or new. This kit is available free for affected users from Hewlett-Packard by calling 800/538-8787. I don't have the serial number range handy.
The upgrade kit is better described as a hardware patch. The early DeskJets and DeskWriters used a cartridge cradle that wasn't perfectly airtight. As a result, the cartridge could prematurely dry out. The classic symptom of the problem is when someone gets only 200-300 pages out of a cartridge instead of the 500 page design limit. Usually, the print quality will be terrible for most of those 200-300 pages.
The upgrade kit consists of a new cartridge cradle and a little tool with which to install it. You use the tool to remove the old parts and to install the new parts. After you install the kit, (it takes about five minutes), you will notice better print quality and many more pages per cartridge. Refilled cartridges especially like the new sled.
Hewlett-Packard -- 800/538-8787