The Xerox Phaser 8550 is great for printing basic stuff like invoices. The only consumables are paper, a maintenance kit, and color wax sticks. The latter is the most expensive over time. Photo samples received prior to purchase are absolutely stunning but consume too much wax. With its PostScript engine and Pantone certification, the 8550 could be used for occasional graphics but there are more worthy printers available for professional output.
Early on it was determined that third-party solid ink sticks would suffice for office use. The premiere manufacturer of compatible sticks is Media Sciences. They guarantee compatibility and satisfaction -- even offering to pick up the tab for repairs should it be proven that their product is the cause of printer damage.
The problem with switching from OEM (original equipment manufacturer) sticks to third party is the printer can hold about five sticks of each color -- cyan, magenta, yellow and black (CMYK). As a color gets used up, another slides down. Therefore, two to four OEM sticks can already be inside the printer when third-party ones are first added. Months could go by before the two products blend and later completely replace the OEM sticks. Because of this, initial reactions are deceptively vibrant.
Fast forward to after OEM wax has been completely replaced. A comparison of the Xerox Light Stripes Test reveals CMYK color fidelity disparity. OEM color is much brighter and black is darker. Media Sciences tech support indicates that oxidation occurs during prolonged periods of inactivity. An ink reservoir stores warmed wax. Without printing for months, the warmed pigment changes properties. To purge the ink reservoirs, it is necessary to print 50 or more pages of solid color for each oxidized color. If discoloration on the Light Stripes Test page is evident, choose from the printer control panel: Troubleshooting > Print Quality Problems > Eliminate Light Stripes > Advanced. Follow the instructions.
For the most vibrant colors, OEM is recommended at about $90 for three sticks (CMY). Third-party wax sticks run about $60 for five sticks (CMY). Same prices for black gets you an extra two sticks. Third-party color should be acceptable but definitely does not match. When a significant divergence in fidelity is apparent and the printer has been idle for a long period of time, purge the oxidized ink. If the prolonged inactivity is expected, power down the printer to prevent oxidation. If these steps do not correct the problem, a new printhead is required.