After testing and printing a huge number of labels we have been able to bring the ink level status of the yellow cartridge inside our Epson TM-C3500 down to EMPTY. The cyan and magenta cartridge have the status LOW INK.
For a fully functional refilled cartridge it is necessary to have the suitable, pigmented refill inks and the dedicated chip resetter available. For filling the ink into the cartridge we work with simple refill syringes and special fill tips. the tips work like a simple refill tool.

In the first step we reset the chip which is mounted on each of the inkjet cartridges inside an Epson TM-C3500 label printer. The resetter has two rows contact pins - one with 4 pins and the other with 3 pins. On the chip there are the matching contact points. Position the resetter above that the 4 pins meet the 4 contact points on the chip and the resetter´s 3 pins link to the chip´s 3 contact points. The resetter´s reset sequenz is activated by pressing down the resetter on the chip gently. The LED blinks red at the beginning and switches to shine green when the reprogramming of the chip completed sucessfully.
We recommend to reset the chip as the first step as it only makes sense to refill an original Epson cartridge with valuable refill ink as long as the chip on it is intact.

Each of the inkjet cartridges of a Epson TM-C3500 has two separate ink bags inside. Each bag has its own ink port on the cartridge´s front side. The ink bags get refilled individually with pigmeted refill ink - one after the other. In the second step we extract the residual ink from both ink bags. Therefore we use the fill tip mounted on an empty refill syringe. Insert the fill tip into the ink port carefully an pull out the ink remaining inside the ink bag. The bag is fully empty when the syringe´s plunger cannot be pulled out any more. Keep the extracted ink to use it for refilling later on.

In original condition the original Epson TM-C3500 inkjet cartridges are filled with a total of 32 ml pigmented ink. Therefore we fill each of the ink bags with 16 ml pigmented refill ink each. This explains why the extraction of the residual ink at the beginning is beneficial. It makes it more easy to calculate which amount of refill ink is needed to fill the empty cartridge again. And it protects the bags from beeing damaged by overfilling.
We split the 16 ml per bag into two fillings of the refill syringe. First we fill 9 ml, followed by another 7 ml - in total 16 ml into each ink bag.

There are 10 ml pigmented refill ink inside the refill syringe and the refill tip is mounted. Insert the fill tip into the left ink port carefully and press 9 ml refill ink into the ink bag. 1 ml refill ink remains in the syringe. Take again refill ink into the syringe - until there are around 8 ml ink inside. Then fill 7 ml more into the left side´s ink bag. Again there remains 1 ml of ink inside the syringe. This excess ink prevents that air is pressed into the ink bag.
Repeat that process for the ink bag in the cartridge´s right side.

The same way as the yellow Epson TM-C3500 cartridge we have refilled and reset the cyan and the magenta cartridge. Having the refilled cartridges beside the label printer we switch it on and on its display the missing cartridges are shown. To install the refilled cartridges we open the cover on the printer´s front side and set the cartridges in - each into its dedicated slot.
On the display the result of the refill can be seen immediately. All refilled cartridges are recognized and have the ink level status FULL again. The Epson TM-C3500 is ready for the next print jobs of product labels, bottle labels and many more.