Hello, thanks for your answer!

We use the following:
Inks: https://www.aliexpress.com/item/Empt...615706040.html
Mugs: https://sublimacia.sk/en/white-mugs/...-a-trieda.html
Paper: https://sublimacia.sk/en/prenosovy-p...a4-100-ks.html
Time and temperature: 110-120 s, 160°C . 165°C
Press: http://www.rezacieplotre.sk/lisy_CY/index_cy.htm - the first one, it is in slovak though, so you probably wont understand it. We recken the problem is due to the press.