I did new tests today. (This quarantine gives time for research and development 🙂 )
I checked the proposed parameters 180 C / 15 s / average pressure then 10 s rubbing … OK. it is possible to get a transfer, but not every time and the small elements of the raster usually do not transfer well and often do not stick well to cotton. So I did more tests, these are my conclusions:
1 / The toner from the printer enters the chemical reaction at high temperature to form an adhesive gel. The higher the temperature, the more this gel is liquid and easy to apply to cotton. 180 C is the minimum, but 190 C or 200 C gives better cotton penetration.
2 / After opening the press, the gel begins to cool and the polymerization of this compound begins. My measurements show that polymerization begins below 120 C.
3 / After polymerization, a subsidence is formed which solidifies to the consistency of a plastomer (synthetic rubber). This happens at a temperature below 70 C.
4 / Reheating the resulting plastomer only causes its softening, but does not break polymer particles, so there is practically no way to press this substance more strongly into cotton.
For my engineering mind, I need to heat it in to cotton under high pressure, preferably at a temperature of 190 – 200 C. Then cool evenly below 120 C, but not lower than 70 C and then remove the transfer paper. Repressing at 180-200 C for 30 s does not add much to the force with which the plastomer clings to cotton but affects the appearance of the transfer surface.
My optimal parameters are:
1 / Transfer 190 C / 30 s.
2 / Cooling on the bottom plate of the transfer press with rubbing to the temperature of 90 C. When the pyrometer in the middle of the transfer shows me the correct temperature, I peel off the transfer paper with a smooth movement. 100% success and repeatability!
3 / Repressing 180 C / 30 s for a more matt surface and peace of mind :). Baking paper from ROSSMANN works best 🙂
I wish everyone health in these hard times. I hope that we will return to earning money soon;).