Refilling the HP4L Toner Cartridge
                      by Michael 'Papa' Hebert

The HP4L printer provides exceptional 300 dpi printing performance at
a very economical price. Unfortunately this economy does not extend
to its combination imaging drum/toner cartridge. Canon, the builder
of the HP4L's print engine, did not design the HP92274A cartridge to
be rebuildable like the cartridges used with the older SX and CX
engines. The imaging drum is smaller and the body of the cartridge is
permanently sealed. It was meant to used once and sent back to HP for
recycling of materials.

Due to the small diameter of the drum, it rotates roughly twice as
many times per page in comparison to the older designs. The microfine
toner is somewhat more abrasive than coarser toners. This leads to a
considerably shorter lifespan. Fortunately the coating on the drum is
"over-spec'ed". Although HP and Canon rate the cartridge at 3000
copies you can get twice that many copies with good results - three
times their spec if you are talking text only.

The procedure for refilling is simple but the process is somewhat
messy. The first thing you need to do is drill a hole in the waste
reservoir. This should be done with a _sharp_ 1/4" drill bit at low
speed and light pressure. On the nose of the cartridge there are
three illustrations molded into the top of the waste reservoir. The
one closest to the center shows a thermometer. At the upper right
corner adjacent to the thermometer picture is the word "No". Position
your drill bit in the letter "o" and drill right through - keep the
speed and pressure low to prevent warping the cartridge body or
vibrating the "doctor blade" inside the waste reservoir out of
position.

Now you can dump the waste toner. Do this outside standing upwind of
the cartridge. Simply hold the cartridge upside down and shake it
until no more toner comes out. You can use a vacuum if you like but
it is really not necessary. After you have dumped the toner wipe any
remaining residue off the top of the waste cartridge then place a
piece of tape over the hole.

Lay the cartridge on its top with the nose pointing away from you.
Make sure that you are indoors or in a shaded area then disregarding
the warning note on the shutter that says, "Caution - Do not open door
- Do not touch drum" pull the shutter back towards you.  Inspect the
surface of the drum. You will probably see some slight scoring of the
surface - this is normal. There will usually be some black toner
particles clinging to the drum's surface. These may be cleaned off
with a soft moistened cloth or paper towel but it really isn't
necessary to do so. What you are looking for is evidence of any deep
score marks or a "dull" appearance of the drum's surface. It should
still be a shiny green.

Stand the cartridge on its left side. Within the recessed area you
will see a gray nylon plug. Pull the shutter bail back out of the way
then insert a thin bladed screwdriver at one side of the plug. Use a
longnose pliers or hemostat to grab the plug then remove it with a
rocking, pulling motion. Be careful that don't puncture the plug.

The cartridge is now ready to be refilled with microfine toner from
Static Controls Corporation. Use a rolled up piece of paper to make a
simple disposable funnel. Insert the small end into the reservoir
hole then slowly pour the toner in while tapping the paper funnel to
keep the toner moving down into the reservoir. When the toner bottle
is empty put the plug back into the hole. Use the handle of a small
screwdriver or other small, smooth surfaced instrument to ensure that
the plug is firmly seated. With a small soft-bristled brush clean off
any toner than has gotten onto the surface of the cartridge.

If you are not going to put the refill into immediate use store it
flat resting on its bottom. Do not store it nose down as shown on the
HP packaging since this may cause some toner leakage.

Before putting the refill into service gently shake it from side to
side to distribute the toner evenly. Print a couple test pages. This
will "clean" the surface of the drum and let you check the print
quality.

I find that I can get "good as new" performance on the first refill
with both text and graphics. Second refills show some deterioration
when printing dark graphic fills but text still appears good. Third
refills are not recommended - the drum will usually be too badly worn
to be useable except for "draft" copies of text.

So ... now all you need is a source for the toner.

I buy mine in case lots of 10 bottles from:

                       Static Control Components
                       PO Box 152
                       Sanford, NC 27331-0152
                       Phone (800) 356-2728

Cost, in case lots of 10 bottles, is $6.49 per bottle plus shipping.
A full case of toner costs about the same as one new cartridge.
Refilling just once per cartridge will cut your per page cost from
2.5 cents to about 1.4 cents/page. Refilling twice will cut your
costs down to the magic penny-a-page point.

Give it a try - I think you'll find the savings well worth the effort
and mess involved.

'Papa'