Before inserting a black, magenta, yellow or cyan toner cartridge into your laser printer, you may see a coating of white or yellow toner powder that appears on the developer roller of your toner cartridge. This is even the case for HP OEM cartridges - there is no need to worry, however.
But what exactly is it and what is its purpose? The slim coating of white or yellow toner powder is completely normal and occurs when the toner is being manufactured.
The colour (white/yellow) is utilised so that it can blend with the chosen colour of the toner cartridge itself. Its purpose is to coat the inner elements of the toner cartridge, as well as for testing to ensure its quality.
The white/yellow toner powder normally vanishes prior to printing out the initial few pages – also if you choose to do a quick calibration when setting up the toner cartridge, it will be removed then too.